The Singapore Engineer July 2019 by The Singapore Engineer

THE MAGAZINE OF THE INSTITUTION OF ENGINEERS, SINGAPORE

THE SINGAPORE ENGINEER

www.ies.org.sg

July 2019 | MCI (P) 105/03/2019

COVER STORY: OVERCOMING SITE-RELATED CHALLENGES TO CREATE AN ICONIC EDUCATIONAL BUILDING

PLUS

CIVIL & STRUCTURAL ENGINEERING: Numerical Modelling of NATM and Underpinning Works underneath an Exis ng Underground MRT Sta on RAILWAY & ROAD ENGINEERING: Cross Passageway Spacing Provision for Railway Tunnels CONSTRUCTION MANAGEMENT: Using BIM for Construc on QA/QC

CONTENTS FEATURES COVER STORY

18 Overcoming site-related challenges to create an iconic educa onal building The ARC was a Winner of the Design and Engineering Safety Award 2019, at BCA AWARDS 2019.

CIVIL & STRUCTURAL ENGINEERING

23 Numerical Modelling of NATM and Underpinning Works underneath an Exis ng Underground MRT Sta on 3D geotechnical finite element method so ware was used to predict the exis ng condi on of the piled ra founda on and its behaviour if subjected to future underground connec on development.

RAILWAY & ROAD ENGINEERING

30 Cross Passageway Spacing Provision for Railway Tunnels The cri cal factors considered in a study that was undertaken and the results are presented.

President Prof Yeoh Lean Weng Chief Editor T Bhaskaran t_b_n8@yahoo.com

Publica ons Manager Desmond Teo desmond@iesnet.org.sg Publica ons Execu ve Queek Jiayu jiayu@iesnet.org.sg

Editorial Panel Dr Chandra Segaran Prof Simon Yu Dr Ang Keng Been Mr Gary Ong Dr Victor Sim Mr Syafiq Shahul Media Representa ve Mul Nine Corpora on Pte Ltd sales@mul 9.com.sg

THE SINGAPORE ENGINEER July 2019

Design & layout by 2EZ Asia Pte Ltd Cover designed by Irin Kuah Cover main image by DCA Architects Pte Ltd /KIRK Cover inset image by KTP Consultants Pte Ltd Published by The Ins tu on of Engineers, Singapore 70 Bukit Tinggi Road, Singapore 289758 Tel: 6469 5000 I Fax: 6467 1108 Printed in Singapore

www.ies.org.sg

RAILWAY & ROAD ENGINEERING 36 A high performance cold recycler for the structural rehabilita on of roads The advantages oďŹ&#x20AC;ered include lower consump on of materials such as binders, faster comple on of projects, and sustainability.

PROJECT APPLICATION 38 Installing heavy and fragile wall panels on a congested project site The work was part of a government rail upgrade programme in Australia.

40 Formwork solu ons for The Madison Tower in London Challenges were successfully overcome in the construc on of the 182 m-high residen al building.

CONSTRUCTION MANAGEMENT 43 Using BIM for Construc on QA/QC It is simpler than imagined.

REGULAR SECTIONS 04 INDUSTRY NEWS 46 IES UPDATE

The Singapore Engineer is published monthly by The Ins tu on of Engineers, Singapore (IES). The publica on is distributed free-of-charge to IES members and aďŹ&#x192;liates. Views expressed in this publica on do not necessarily reflect those of the Editor or IES. All rights reserved. No part of this magazine shall be reproduced, mechanically or electronically, without the prior consent of IES. Whilst every care is taken to ensure accuracy of the content at press me, IES will not be liable for any discrepancies. Unsolicited contribu ons are welcome but their inclusion in the magazine is at the discre on of the Editor.

THE SINGAPORE ENGINEER July 2019

INDUSTRY NEWS

CAPITALAND AND ASCENDAS SINGBRIDGE COMPLETE

TRANSACTION TO FORM A SINGLE ENTITY CapitaLand Limited has completed its transac on with Temasek and acquired all the issued shares of each of Ascendas Pte Ltd and Singbridge Pte Ltd, crea ng one of Asia’s largest diversified real estate groups with over SGD 123 billion of assets under management. The transac on had earlier received overwhelming approval by CapitaLand’s independent shareholders at an Extraordinary General Mee ng held on 12 April 2019. With the comple on of the transac on, the enlarged CapitaLand Group will operate as a unified en ty from 1 July 2019 as it marks a new chapter of combined competencies and scale. Spanning over 30 countries across more than 200 ci es are the group’s enhanced real estate value chain and enlarged global network of commercial, retail; business park, industrial and logis cs; integrated development, urban development; residen al; lodging; as well as fund and asset management businesses. Mr Lee Chee Koon, Group CEO of CapitaLand Group, said, “The comple on marks the coming together of two leading real estate players as one unified en ty. As an

enlarged group, we possess fully integrated capabili es in four core markets - Singapore, China, India and Vietnam, while building greater scale in developed markets. With more asset classes in these markets, we will go further to achieve transforma onal growth. Diversifying our por olio to new economy sectors, such as business parks, logis cs and industrial proper es, will give us added compe ve edge via a bigger global network of touchpoints. With greater access to the best talents, capital partners, markets and asset classes, we are confident of building CapitaLand into a winning global company”. CapitaLand announced, in May 2019, the group’s key execu ve appointments and business organisa on structure, which were scheduled to come into eﬀect on 1 July 2019. The enlarged group is organised along geographical lines covering Singapore, China, India, Vietnam and other developed markets, for its commercial, retail; business park, industrial and logis cs; integrated development, urban development; and residen al businesses. The lodging business as well as the fund and asset management business are organised as standalone sectors.

NEW INTEGRATED TRAIN TESTING CENTRE FOR GREATER RAIL RELIABILITY The Land Transport Authority (LTA) will construct a new Integrated Train Tes ng Centre (ITTC) to perform integrated systems tes ng for all new and exis ng MRT lines. Occupying an area of approximately 50 hectares at the former Raffles Country Club site, the ITTC will be equipped to robustly test trains and other core railways systems (for example, electrical, mechanical and signalling systems) round-the-clock, without affec ng passenger services on the main lines. This is similar to tes ng centres in other countries with extensive rail networks, such as Germany, Korea and Japan. The ITTC will support ongoing efforts to renew, upgrade and expand the rail network. It is expected to enhance rail reliability, while freeing up limited engineering hours and reducing the need for line closures. The facility will start receiving trains for Circle Line 6 around end-2022. Over me, the ITTC can grow into a hub for LTA and the local rail industry to develop deeper Opera ons and Maintenance competencies and achieve engineering excellence. The facility will provide railway workers with training opportuni es, giving them a first-hand understanding of the intricacies of new rail systems before they are deployed. Equipped with a rolling stock facility, the ITTC can carry out mid-life train refurbishment

THE SINGAPORE ENGINEER July 2019

projects. The ITTC can also serve as a tes ng ground for the local rail industry to evaluate new railway infrastructure, develop proofs-of-concept, as well as conduct research & development work on railway technologies. LTA Deputy Chief Execu ve (Infrastructure and Development), Mr Chua Chong Kheng said, “The ITTC allows for robust tes ng of our trains and integrated systems before they are deployed on opera onal lines. This approach frees up precious engineering hours for other ac vi es, such as railway maintenance, and reduces the need for future ‘early closures’ and ‘late openings’. In addi on, LTA will be able to speed up the diagnosis and rec fica on of faults with the ITTC, as troubleshoo ng can now be done locally”. LTA will call a contract to design and build the ITTC over the next few months. This will comprise an endurance loop test track, a performance and integra on loop test track, a straight high-speed test track and other suppor ng track facili es. Other facili es such as oﬃces, an opera ons control centre, a maintenance workshop and a refurbishment workshop will also be included in the scope of work. Construc on of the ITTC is expected to start in mid-2020.

STARTUPS RECEIVE SGD 650K SEED FUNDING FROM

MPA TO DEVELOP INNOVATIVE SOLUTIONS The Mari me and Port Authority of Singapore (MPA) and NUS Enterprise, the entrepreneurial arm of the Na onal University of Singapore (NUS), announced in April 2019 that each of the 13 technology start-ups from the Smart Port Challenge (SPC) 2018 received SGD 50,000 in seed funding from MPA to develop and test-bed their innova ve solu ons. One of the recipients of the seed funding was Claritecs. Ms Marianne Choo, Chief Marke ng Oﬃcer of Claritecs, said, “Claritecs was one of the youngest start-ups at the 2018 Smart Port Challenge, and we achieved a Top 3 win with ‘BunkerMaestro’, an algorithm-based pla orm to rejuvenate bunker scheduling opera ons, with datadriven insights for increased work eﬃciencies, scheduling clarity and fleet op misa on. “We will enter the test-bed phase from next month, with five bunker tanker operators who collec vely manage one-third of Singapore’s bunker tanker fleet. We are

very grateful to obtain (the) seed funding from MPA, as it will go a long way in helping us - a 14-month old company at pre-revenue stage - to sustain development of BunkerMaestro and its subsequent market roll-out.” According to a joint statement by MPA and NUS Enterprise, the seed funding will be used to support prototype development, test-bed solu ons and further develop prototypes a er gathering industry feedback. Twelve of the start-ups were also given the opportunity to pitch their solu ons to venture capitalists at the inaugural Mixer and Pitch Session held as part of the Singapore Mari me Technology Conference (SMTC) 2019. The session was held to strengthen the development of the mari me innova on ecosystem and open up opportuni es in the mari me industry for start-ups and venture capitalists. Among the venture capitalists who par cipated were EV Growth, Futurelabs Ventures, Green Meadows Accelerator, SG Innovate, and TNB Ventures.

MIT OPERATED SATELLITE DISCOVERS ITS FIRST EARTH SIZED PLANET NASA’s Transi ng Exoplanet Survey Satellite (TESS), operated by MIT, has discovered its first Earth-sized exoplanet. The planet, named HD 21749c, is the smallest world outside our solar system that TESS has iden fied. The new planet orbits the star HD 21749 which is just 52 light years from Earth. It is likely a rocky and uninhabitable world, as it circles its star in just 7.8 days – a rela vely ght orbit that would generate surface temperatures on the planet of up to 800 degrees Fahrenheit. According to the MIT-led team of astronomers, the discovery of this Earth-sized world is “exci ng”, as it demonstrates TESS’ ability to pick out small planets around nearby stars. In the near future, they expect the probe should reveal even colder planets, with condi ons more suitable for hos ng life. “This would be our first one, and it’s a milestone for TESS. It sets the path for finding smaller planets around even smaller stars, and those planets may poten ally be habitable,” said lead author and TESS member Dr Diana Dragomir, a post-doctoral fellow in MIT’s Kavli Ins tute for Astrophysics and Space Research. TESS has been hun ng for planets beyond the solar system since it launched on 18 April 2018. The satellite

is a NASAsponsored Astrophysics Explorerclass mission that is led and operated by MIT, and is designed to observe Conceptual illustra on of TESS. Image: NASA Goddard nearly the Space Flight Center. en re sky, in overlapping, month-long patches, as it orbits the Earth. As it circles Earth, TESS focuses its four cameras outward to monitor the nearest, brightest stars in the sky, looking for any periodic dips in starlight that could indicate the presence of an exoplanet as it passes in front of its host star. Over its two-year mission, the mission aims to iden fy for the astronomy community at least 50 small, rocky planets, along with es mates of their masses. To date, the mission has discovered 10 planets smaller than Neptune, with the masses of four of the planets es mated.

INDUSTRY NEWS

SELETAR AEROSPACE PARK TO OFFER INDOOR TESTBEDS FOR COMMERCIAL DRONE TESTING JTC and the Associa on of Aerospace Industries Singapore (AAIS) are launching a new joint ini a ve this year to provide indoor testbeds within Seletar Aerospace Park for commercial applica ons of Unmanned Aircra Systems (UAS). These readily available indoor spaces are housed within JTC’s high-rise developments at Seletar Aerospace Park, and will provide a safe and controlled environment for companies to conduct development trials and customer demonstrations. Implementation details are being worked out and companies that are keen to tap on these spaces can approach AAIS to register their interest.

AAIS Chief Execu ve Sia Kheng Yok said, “UAS are finding applica ons in fields as diverse as smart ci es, security, agriculture, mining, construc on and resource management … Our partnership with JTC is an excellent example of our concerted eﬀorts to facilitate innova on and provide a launchpad for this promising industry.” Ms Glory Wee, Director, Aerospace, Marine & Urban Solu ons Cluster, JTC said, “The provision of these indoor testbeds at Seletar Aerospace Park will support the development and commercialisa on of UAS technologies. The UAS and aerospace communi es are complementary, and we are confident this new ini a ve will enable more industry partnerships to be catalysed in Singapore.”

THE SINGAPORE ENGINEER July 2019

INDUSTRY NEWS

NTU SCIENTISTS INVENT HANDHELD DEVICE FOR QUICK MONITORING OF DRINKING WATER QUALITY Scien sts from NTU have developed a portable device to detect trace levels of heavy metals in drinking water in just five minutes. Inspired by the human body, it makes use of an organic substance called a chela ng agent. Exis ng in the bloodstream, it binds to heavy metal ions, preven ng them from interac ng with other molecules and enzymes, and marks them for excre on. Combining the agent with an op cal measurement system, Associate Professor Yong Ken-Tye and Professor Tjin Swee Chuan from the School of Electrical and Electronic Engineering developed a device that generates test results quickly on the spot, making the device convenient for on-site water tes ng. In a contaminated water sample, the metal ions will bind to the chela ng agent on the op cal fibre sensor. This induces a shi in the output light spectrum, from which the device’s processing unit takes about five minutes to calculate the concentra on of heavy metals. Typically, drinking water quality is monitored via laboratory tests as heavy metals cannot be iden fied by colour, taste, or odour, unless present at high levels. While highly accurate, they take at least a day to complete.

Some portable devices on the market provide faster results, but may require the addi onal step of mixing the water sample with a buffer solu on first. The sensor for such kits also has to be used within 30 minutes a er exposure as the effec veness of the sensor can be affected by air, heat, or humidity. Other mobile alterna ves either run the risk of re-introducing heavy metal contaminants into the environment or rely on subjec ve interpreta ons of colour changes. Compara vely, the NTU inven on works in the field and requires just a few drops of a water sample into a disposable sensor cartridge to detect heavy metals at parts-per-billion precision. The NTU device’s sensor is also not limited by exposure to air, and remains effec ve up to a temperature of 40 degrees Celsius. A er filing two patents, the NTU team has now successfully incorporated a spin-off, Waterply, which is working with local companies to collect more data to improve the accuracy of the device. Prof Tjin added that the team was also exploring ways to apply the technology for domes c use, such as in water filtra on systems and electric water ke les.

DE NORA WATER TECHNOLOGIES APPOINTS NEW CEO De Nora, a global leader of sustainable technologies, has appointed Dr Mirka Wilderer as Chief Execu ve Oﬃcer of the company’s Water Technologies group. In her new role, Dr Wilderer will be looking to bolster the company’s revenue growth through a strategic pipeline consis ng of geographic and Dr Mirka Wilderer applica on market expansion, technology advancements, and improved processes that will bring an enhanced 21st century experience to De Nora Water Technologies’ global customer base. Having worked in multiple markets across Europe, Asia and the US, in the last 15 years, Dr Wilderer brings a wealth of water industry experience to De Nora. She was born and raised in Germany, and holds a

THE SINGAPORE ENGINEER July 2019

doctorate in international management. Dr Wilderer first joined De Nora in February 2019 as global integration director. De Nora CEO, Paolo Dellachà, said, “We are thrilled to have Mirka on the De Nora management team. She has a strong track record of successfully applying innova ve solu ons to leading change and managing business transforma on, and I am confident that her excep onal leadership skills, coupled with the gi for fostering crossfunc onal collabora on, will spur strong growth for our Water Technologies business”. Dr Wilderer said, “I have spent much of my life surrounded by people with a passion and pride for caring for water, beginning with my parents who were both devoted water professionals. With a real passion for interna onal management, I am excited to be a part of a company with a truly global footprint - a presence around the world including emerging markets like China, Japan and Brazil”.

I BUILD ON EXPERIENCE I see the possibilities my career can bring. Because a career in the built environment is one that can create direct yet far-reaching impact. At BCA, my work on policy measures help to drive change in the built environment sector and make a positive difference. We constantly shape the landscape to prepare for the future of Singapore, rally the built environment sector to achieve farreaching goals beyond today, and improve the living environment for Singaporeans from all walks of life. Be part of this transformation, and join us for a fun and meaningful career. Find out more about our career opportunities at www.bca.gov.sg

Lim Yong Xian Senior Engineer

INDUSTRY NEWS

BCA PARTNERS INDUSTRY AND UNIVERSITIES TO GROOM LEADERS TO TRANSFORM THE BUILT ENVIRONMENT SECTOR The Building and Construc on Authority (BCA) has partnered the built environment industry and academia to develop a new iBuildSG Leadership Engagement and Development framework (iBuildSG LEAD framework) to support leadership development within the sector. BCA is also working with the industry to pilot a new, voluntary Maintainable Design Appraisal System (MiDAS) from May this year. These ini a ves were announced at the BCA AWARDS 2019 ceremony by Minister of State for Na onal Development and Manpower, Mr Zaqy Mohamad. More than 2,000 industry guests were present to celebrate the built environment sector’s achievements.

iBuildSG LEAD framework The iBuildSG LEAD framework is an ini a ve under the Construc on Industry Transforma on Map to develop leaders within the workforce who can drive sustained industry transforma on eﬀorts. Targeted at young emerging leaders, to poten al and exis ng C-suite leaders, the framework aims to build leadership capability and capacity at various levels. • At the industry level, the framework builds collec ve stewardship and develops networks for leaders to foster strong collabora on across the construc on value chain. • At the firm level, the framework supports firms in developing talent and growing their leadership pipeline so each firm has the bench strength to grow domes cally and abroad. • At the individual level, the framework helps industry prac oners build up their competencies to advance the sector, and recognises those with outstanding contribu ons. There will be three leadership building pla orms within the framework, anchored by two bespoke structured programmes, LEAD Horizon Programme and LEAD Milestone Programme. BCA will partner the Singapore Management University (SMU) as the anchor ins tu on for both the Horizon and Milestone Training Programmes. SMU’s strengths in industry collabora on and management skills will enhance the par cipants’ leadership competencies in these areas. In addi on, BCA will collaborate with the Singapore University of Technology and Design (SUTD) on a technical track, within the LEAD Horizon Programme, to run an innova on bootcamp. To complement the above, a third pla orm, Insights@LEAD, comprising a series of events and ini a ves, will further thought leadership and provide opportuni es for co-crea on through alignment and collabora on across the LEAD community. 12

THE SINGAPORE ENGINEER July 2019

“SMU is delighted to partner BCA to launch two bespoke structured training programmes under the new iBuildSG LEAD framework. These programmes aimed at the middle level leaders and enterprise leaders in the built environment sector represent a fusion of experien al and interac ve learning, facilitated by experienced SMU faculty and industry leaders. We are confident that our programme par cipants will value the many real-life case studies, prac ce-driven approach to teaching, and networking opportuni es. With exper se in delivering tailored and industry-specific programmes, SMU’s Execu ve Development presents a robust oﬀering that will well address the needs of leaders and senior execu ves who are tackling today’s challenges”, said SMU President, Professor Lily Kong. “SUTD is pleased to promote leadership in innova on by design, in partnership with BCA, through the new iBuildSG LEAD Framework. Leveraging SUTD’s unique strength in design innova on and ac ve learning pedagogy, we look forward to equipping the par cipants with essen al knowledge and skills to take on tomorrow’s challenges and stay future-ready. The training programme designed for BCA can be incorporated into SUTD Academy’s ModularMaster programmes, which can in turn lead to Master’s programmes, thereby providing a pathway for par cipants to up-skill themselves as desired”, said Professor Chong Tow Chong, SUTD President.

MiDAS As part of the ini a ves to upli the Facili es Management (FM) sector - a key focus under the Real Estate Industry Transforma on Map - BCA brought together the industry, unions, and other public agencies to form a Tripar te FM Implementa on Commi ee (FMIC) to develop, oversee, and review the implementa on of the sector’s transforma on plans. FMIC iden fied Design for Maintainability (DfM) as a key pillar in transforming the FM sector. DfM is the prac ce of integra ng opera ons & maintenance considera ons into project planning and design to achieve effec veness, safety, and economy of maintenance tasks. BCA has worked with the industry and two ter ary ins tu ons - SUTD and the Nanyang Technological University (NTU) - on a new, voluntary Maintainable Design Appraisal System (MiDAS) which assesses the degree of maintainability of building designs from the lens of labour efficiency and cost-effec veness of downstream maintenance regimes. Through MiDAS, BCA aims to achieve the following: • Foster greater collabora on among designers, developers, and FM prac oners to deliver be er and more maintainable designs.

INDUSTRY NEWS

• Promote holis c sustainability by considering not only environmental aspects but also economic and social aspects, through reducing costs and reliance on manual labour for building maintenance. • Enable designers and developers to make more informed design decisions upfront and take a life-cycle view of the development - including considera on of not only ini al capital expenditure but also opera ng expenses. MiDAS will be piloted in about 10 public and private projects including the new Surbana Jurong Campus; Ascendas Singbridge’s integrated development, Ascent; and PSA’s new oﬃce building at Pasir Panjang. To raise awareness of the importance of DfM and help the industry keep abreast of good DfM prac ces, including safe maintenance access, use of appropriate building materials and adop on of technology, in order to enable eﬃcient maintenance ac vi es downstream, BCA collaborated with industry stakeholders and government agencies to put together a set of DfM guides.

Built Environment Leadership Award At this year’s BCA AWARDS, local builder, Tiong Seng Contractors (Private) Limited, emerged as the top winner of the Built Environment Leadership Award - clinching the pinnacle Pla num Star. Tiong Seng has maintained the Pla num status for the past five years, demonstra ng its strong leadership, excellence and innova on in Singapore’s built environment industry. The company has con nued to push the boundaries for building innova ons, its latest achievement being in-house developed and patented Prefabricated Prefinished Volumetric Construc on solu ons which incorporate advanced ultra-high performance duc le concrete (UHpDC). UHpDC has up to five mes the compressive strength of normal concrete, enabling robust yet slimmer concrete panels to be made, for eﬃcient transporta on, li ing and installa on works.

A large number of awards presented This year’s BCA AWARDS saw 536 accolades given out to project teams, developers and prac oners for their outstanding achievements in delivering exemplary projects and upholding best prac ces in the areas of safety, quality, sustainability, produc vity and universal design. Mr Hugh Lim, BCA CEO, said, “Over the past 20 years, BCA has worked with our partners to develop the industry and shape the Singapore skyline. The industry has built up much exper se and some have even brought the strong Singapore brand represen ng quality and sustainability beyond our shores. I congratulate all the award winners for their outstanding achievements and look forward to con nue our work with the industry to transform our sector, oﬀer good jobs for Singaporeans and change the way we build Singapore”.

The Award The BCA Built Environment Leadership Award was introduced in 2009 to recognise outstanding industry organisa ons such as developers, consultants (Architectural, Structural and M&E) and builders, who have demonstrated excellence and leadership in building a safe, high quality, sustainable, friendly and produc ve built environment in Singapore. It also aims to serve as a comprehensive roadmap for the building and construc on industry to level up and spur these organisa ons towards a higher degree of professionalism with enhanced capabili es and compe veness. Award categories The awards are given out under the following six categories - Developer / Owner, Architectural Consultant, Structural Consultant, M&E Consultant, Mul Disciplinary Consultant, and Builder. Assessment criteria Applicants must meet the following eligibility criteria to be considered for the awards: • Achieve an overall score of at least 70 points (Gold), 80 points (GoldPLUS) or 90 points (Pla num) based on the evalua on criteria established for the awards. BCA also introduced a higher award in 2018, the Pla num Star, for applicants who fulfil the following criteria: - Meet all requirements of a Pla num Award. - Hold the Pla num Award for at least five years. • Applicants must not have any significant issues arising from their business / ac vi es in the areas of building safety, quality, sustainability and user-friendliness that could lead to adverse publicity or tarnish the reputa on of the awards. Award Type

Company

Category

Pla num Star

Tiong Seng Contractors (Private) Limited

Builder

GoldPLUS

KTP Consultants Pte Ltd Structural Consultant

GoldPLUS

Meinhardt (Singapore) Pte Ltd

Mul -Disciplinary (Structural and M&E Consultants)

GoldPLUS

Squire Mech Private Limited

M&E Consultant

GoldPLUS

Straits Construc on Singapore Pte Ltd

Builder

GoldPLUS

Surbana Jurong Consultants Pte Ltd

Mul -Disciplinary (Architectural, Structural and M&E Consultants)

GoldPLUS

WSP Consultancy Pte Ltd

Mul -Disciplinary (Architectural, Structural and M&E Consultants)

Winners of the Built Environment Leadership Award 2019. THE SINGAPORE ENGINEER July 2019

INDUSTRY NEWS

SP TELECOM TO BUILD AN ALTERNATIVE DATA FIBRE NETWORK IN SINGAPORE SP Telecom, a joint venture between ST Engineering and SP Group, announced in April its plans to build an AIequipped fibre network as an alterna ve to the exis ng network infrastructure in Singapore. The new So ware-Defined Network with Network Func ons Virtualiza on (SDN-NFV) will enable users to have greater control, visibility and scalability in terms of network management. Leveraging AI and machine learning, it can predict and prevent network conges on to ensure uninterrupted connec vity. According to SP Telecom, it also has unspecified built-in cybersecurity capabili es. The company intends to lay its fibre network alongside SP Group’s power lines, crea ng a separate and dis nct network infrastructure from that of other network service providers. Being buried deeper underground, it is more durable than other fibre cables. The new intelligent network will further enhance SP Telecom’s diversified network oﬀering, with “nextgenera on cloud-like agility and flexibility to cater to the dynamic network demands of today’s enterprises”. This is enabled by a cloud-based Business and Opera on

Support System (B/OSS) that allows business customers to request for connec vity services, manage their network requirements dynamically with minimal human interven on, and configure network func ons according to their needs. Customers will also be kept up to date with real- me service deployment updates and alerts. SP Telecom has engaged PCCW Solu ons as its consultancy partner to develop the SDN-NFV fibre network solu on, tapping on PCCW Group’s telecommunica ons, network and informa on technology capabili es. “An increasing number of businesses rely on their communica ons systems for mission-cri cal applica ons. They can no longer aﬀord any down me that can cause major problems and significant losses in terms of costs, produc vity and reputa on,” said Mr Titus Yong, CEO of SP Telecom. “As SP Telecom forges forward towards providing an advanced solu on that supports Smart City developments, we are confident that the consultancy partnership with PCCW Solu ons will enable our plans of becoming an advanced network provider to meet fastevolving digital needs globally.”

FINAL CAISSON INSTALLED FOR TUAS TERMINAL PHASE 1 The Tuas Terminal project reached a milestone, with the 221st and final caisson for reclama on works installed on 23 April 2019, witnessed by Mr Khaw Boon Wan, Coordina ng Minister for Infrastructure and Minister for Transport. The Phase 1 reclama on works are currently more than threequarters complete and on schedule to be fully completed in 2021. PSA Corpora on will then begin terminal development of deep-water berths that are able to handle about 20 million twenty-foot equivalent units (TEUs) per annum. The use of caissons in Phase 1 is a safer and more eﬃcient method of reclama on compared to tradi onal methods such as piling. The caissons used for Tuas Terminal’s construc on are one of the largest in the world. Pre-fabricated onsite, each caisson weighs 15,000 tonnes and measures 40 m in length, 28 m in width and 28 m in height – as tall as a 10-storey building. Together with Dredging Interna onal Asia Pacific- Daelim Joint Venture and Surbana Jurong, MPA has adopted innova ve solu ons, ranging from the pre-installa on of geotex les on caissons on land instead of at sea, and the use of ar ficial intelligence to the use of drones for site survey and progress monitoring.

THE SINGAPORE ENGINEER July 2019

One such innova on is Temarock, a next genera on all-inone rock mound construc on vessel. The vessel automates the construc on The final caisson is filled with dredged materials process, to lock its posi on. Photo: MPA elimina ng the need for rock laying and compac on vessels, survey vessels, and diver support. This enhances eﬃciency and safety. An “Automa c Rebar Machine using Robo cs System” was also deployed to bend and cut steel rebar to the desired specifica ons, before transferring them to the stacking area. Compared to conven onal prac ce, which requires workers to handle the rebar manually, this reduces their exposure to mechanical hazards that would have been present during the process. When Tuas Terminal is fully completed in 2040, it will consolidate all port opera ons in a single loca on and be capable of handling up to 65 million TEUs per annum.

INDUSTRY NEWS

DOWA LAUNCHES

MODERN ASIA ENVIRONMENTAL HOLDINGS DOWA, a leading Japanese waste management and recycling solu ons provider recently announced the forma on of Modern Asia Environmental Holdings (MAEH) in Singapore to strengthen its innova ve offerings locally and regionally. The en ty spearheads DOWA’s strategic expansion across Southeast Asia, by test-bedding cu ngedge solu ons in Singapore and building a network of effec ve waste management and recycling capabili es across Southeast Asia. MAEH brings together the combined capabili es of At the opening of Modern Asia Environmental Holdings (MAEH) in Singapore are, from le , Mr Hideaki Technochem Environmental Kobayashi, President, Modern Asia Environmental Holdings; Ambassador Jun Yamazaki, Embassy of Japan Complex Pte Ltd (Technochem) in Singapore; Guest-of-Honour, Mr Tan Meng Dui, Chief Execu ve Officer, Na onal Environment Agency; and Dowa Eco-System Singapore and Mr Kimio Matsumoto, Director, DOWA Eco-System Co Ltd. Pte Ltd (ESG) under one umbrella, to offer incinera on, can recover up to 22 elements from the electronic waste recycling and precious metal recovery capabili es as it receives. well as an end-to-end approach to help countries in President of MAEH, Mr Hideaki Kobayashi, said, the region address their growing environmental waste “Leveraging the pioneering technology and exper se of management and recycling needs. MAEH also has a 95% DOWA together with the streamlining of our opera ons stake in PT Prasadha Pamunah Limbah Industri (PPLi), in Singapore, we are in a strong posi on to be er serve which provides waste collec on, recycling, treatment our customers here and in the region. We think we can and disposal services in Indonesia. make great contribu ons towards the crea on of a zeroTechnochem specialises in the collec on of chemical waste circular economy that will sustain the long-term waste, water treatment, industrial cleaning services, development of Southeast Asia”. incinera on of waste, and the sale of solvents and For example, in Japan, DOWA has invented a crea ve chemicals. It runs DOWA’s first ver cal combus on way of managing ash, a by-product of incinera on. incinerator outside Japan and the first-of-its-kind Its proprietary ash smel ng technology allows a in Singapore and Southeast Asia, at Tuas Industrial simultaneous separa on of heavy metals from ash in Estate. This incinerator, which occupies a smaller the recycling process, crea ng a molten slag that can physical footprint compared to other facili es, uses a be used for road construc on when combined with breakthrough, super-low, air ra o combus on method cement. MAEH has plans to introduce this technology to that consumes less fossil fuels. It was designed by Singapore and the region. DOWA, in Japan, following the Great East Japanese earthquake in 2011, to clear massive amounts of debris “Singapore provides us with an excellent environment to at disaster sites. MAEH plans to build a similar facility in test-bed some of our state-of-the-art waste management Indonesia through PPLi. and recycling solu ons. It is our hub for Southeast ESG located at Jurong Industrial Estate, on the other hand, carries out precious metal recovery using a hydrometallurgy process. The facility in Singapore can recover gold, silver and palladium from electronic waste, eg gold pla ng scraps, lead frames with plas c, printed circuit boards, ceramic substrates and press-cut waste. Together with DOWA’s facili es in Japan, the company

Asia and also our spring-board to the region. We are grateful for the support that we have received from the Singapore government and for its technological foresight and appe te for innova on”, added Mr Kobayashi. DOWA currently has overseas opera ons in Singapore, Indonesia, Myanmar and Thailand, with a staﬀ strength of almost 1,500 across this region.

THE SINGAPORE ENGINEER July 2019

INDUSTRY NEWS

HEUNG YUEN WAI HIGHWAY IN HONG KONG OPENED The Hari hotel topped out The Atkins-designed ‘The Hari’ hotel in Hong Kong topped out on 9 April 2019. Due to open in 2020, the luxury hotel builds on the success of the Harilela family’s signature hotel in London. It is the first hotel in the Harilela Group that carries its own brand in Hong Kong and Asia. The Heung Yuen Wai Highway comprises approximately 4.8 km of the Lung Shan Tunnel, 0.7 km of the Cheung Shan Tunnel, a 4.5 km viaduct and 1 km at-grade roads.

The Heung Yuen Wai Highway in Hong Kong opened to the public in May 2019. The major transport infrastructure project will promote the development of the Greater Bay Area through enhanced connec vity for passengers and cargo alike. The highway is an approximately 11 km, dual two-lane carriageway connec ng the Fanling Highway and the Heung Yuen Wai Boundary Control Point. The Heung Yuen Wai Highway comprises approximately 4.8 km of the Lung Shan Tunnel, 0.7 km of the Cheung Shan Tunnel, a 4.5 km viaduct and 1 km at-grade roads. Atkins, a member of the SNC-Lavalin Group, and a respected design, engineering and project management consultancy has been suppor ng Dragages Hong Kong Limited, as the detailed design consultant for the major design and build project for the Lung Shan Tunnel sec on, since 2013. Ray Chan, Atkins’ Project Manager, said, “We are extremely proud to have supported our long-term client with this strategic and challenging transport project over the past six years. The project is unique and represents many firsts for tunnelling in Hong Kong. Innova ve design and close collabora on were key to the success of the record-se ng project”. The 4.8 km Lung Shan Tunnel is the longest twin tube road tunnel in Hong Kong. The project engaged the largest EPB (earth pressure balance) TBM (tunnel boring machine) in Hong Kong, with a diameter of 14.1 m. Following the breakthrough of the southbound tunnel sec on on 1 March 2017, the TBM went on to complete a 180° U-turn to start the construc on of the northbound sec on just three months later. It is the first me in Hong Kong that a TBM has completed a U-turn in specially-designed rock caverns, whereas the normal prac ce is to substan ally dismantle the TBM prior to being transported back and set up again at its original launching posi on. This TBM U-turn opera on allowed 16

THE SINGAPORE ENGINEER July 2019

On arrival, hotel guests will pass through a welcoming, covered drop-oﬀ, and ascend to check-in within a luxurious and unique podium lobby. All guest rooms are designed with a vista along Lockhart Road in the district of Wanchai, whilst the penthouses are rewarded with views across the wider cityscape. The full-height glazing of all rooms provides a drama c experience connecting hotel guests to the vibrancy of Wanchai. Atkins was commissioned as architect and lead consultant to deliver the project from concept through to contract administra on, as well as to provide ‘authorised person’ services. Faithful+Gould, Atkins’ project and programme management business, was commissioned to project manage the hotel development.

A view of the hotel from the street.

construc on progress to remain in line with the ght project programme, reducing construc on costs and environmental impact. The project’s innova ve approach for Hong Kong’s first applica on of the TBM U-turning method in underground rock caverns was recognised by the ACEHK Annual Award 2018. The ACEHK Annual Award recognises projects that prove to be the epitome of engineering excellence, incorporate ingenuity, and take considerable measures to ensure sustainability.

INDUSTRY NEWS

KEPPEL WINS HIGHEST NUMBER OF

AWARDS AT WSH AWARDS 2019 Keppel Group has clinched 18 awards at this year’s Workplace Safety and Health Awards (WSH Awards), organised by Singapore’s Workplace Safety and Health Council (WSHC) and Ministry of Manpower (MOM).

“We are encouraged by the WSH Council’s recogni on of our safety eﬀorts and will work even harder to ensure that everyone returns home safe at the end of each working day”, he added.

This is the highest number of awards won by a single organisa on this year. Keppel had also won the highest number of awards in 2018.

Keppel FELS won two of the Innova on Awards, while the other two were won by Keppel Logis cs and Keppel Merlimau Cogen. Keppel FELS’ awards were for the ‘iDiver’, a remotely operated robo c diver which performs hazardous underwater inspec ons on vessels and other underwater structures, in place of human divers, and the ‘Smart Robot’ which automates inspec ons of bus-bar systems located in trenches. Using the Smart Robot has reduced the manpower required for each inspec on from eight workers to two and has achieved a 95% reduc on in manhours required.

Of the 18 awards, Keppel Oﬀshore & Marine (Keppel O&M) received 12 awards under the Safety and Health Award Recogni on for Projects (SHARP) category for exemplary project safety and health management systems. Keppel FELS, a subsidiary of Keppel O&M, also clinched the WSH Performance (Silver) Award for outstanding safety performance and implementa on of strong WSH management systems. Four companies from the Keppel Group garnered WSH Innova on Awards which recognise companies for crea ng solu ons which help to improve safety and enhance opera ons at the workplace. Mr R K Jaggi, General Manager, Group Health, Safety and Environment, Keppel Corpora on, said, “Safety is an integral part of who Keppel is and how we run our business. In our drive towards shaping a safer future for all our stakeholders, we proac vely harness technology and innova on, and always encourage employees to collaborate and think of new ideas to improve work processes.

At Keppel Logis cs, technicians no longer need to work in narrow spaces over extended periods of me to manually lubricate the wire ropes of the cranes in their warehouses. The new ‘Customised Wire Rope Lubricator’ cuts down 98% of man hours needed, and requires just one technician to operate, instead of three needed for the manual opera on. The ‘Smart Chemical Handling’ project team at Keppel Merlimau Cogen designed a device to tackle the risk of chemicals being transferred to wrong tanks, preven ng adverse chemical reac ons that would cause major disrup ons to opera ons.

LENDLEASE RECOGNISED AT WSH AWARDS FOR THE FIFTH YEAR RUNNING For the fi h consecu ve year, Lendlease has been recognised for its commitment to providing a safe and healthy work environment at project sites and across shopping malls. Lendlease Retail and Lendlease Singapore received the WSH Performance (Gold) Award and WSH Performance (Silver) Award, respec vely, at WSH Awards 2019, reaﬃrming Lendlease’s core focus on fostering a culture of care and innova ng to enhance safety performance. In addi on, Lendlease’s Amgen MSB Project received the Safety and Health Award Recogni on for Projects (SHARP). “Health and safety remain our number one priority and we constantly strive to eliminate incidents and injuries across our sites. A culture of care guides our organisa on at all levels and is embedded in the way we conduct business, ensuring everyone can go home safely to their loved ones, every day”, said Ng Hsueh Ling, Managing Director, Singapore and Chief Investment Oﬃcer, Asia, Lendlease. Lendlease takes its commitment to workplace safety seriously. Apart from a robust risk management approach

aimed at preven ng the introduc on and release of harm to workers, the organisa on implements a progressive near-miss repor ng regime and associated data analy cs to promote greater accountability for safe outcomes, in support of WSH Council’s Vision Zero. In addi on, Lendlease believes that inculca ng a culture of care goes a long way in crea ng a safe and healthy work environment for all, enabling trust and ul mately preven ng accidents from happening. For example, through the Lendlease Training Academy, the group puts this culture of care for all into ac on by centralising safety training required by workers and providing a structured framework to boost skills across the board. Going above and beyond, Lendlease constantly looks towards u lising innova ve technologies to deliver improved safety outcomes at its projects and assets. Through the adop on of technologies such as project site biometric access, Building Informa on Modelling (BIM) and drone site surveillance, Lendlease adopts a 360° approach to safety that aims to reduce risks faced during all phases of construc on.

THE SINGAPORE ENGINEER July 2019

COVER STORY

OVERCOMING SITE RELATED CHALLENGES TO CREATE AN ICONIC EDUCATIONAL BUILDING The ARC was a Winner of the Design and Engineering Safety Award 2019, at BCA AWARDS 2019. Introduc on Located along Nanyang Drive, within Nanyang Technological University (NTU Singapore), The ARC is a 6-storey building with two levels of high ceiling workshop areas and four levels of a smart student hub and tutorial rooms, genera ng a total of 18,100 m2 of GFA. The site was previously occupied by a single storey workshop. The reinforced concrete, low-rise structure has an arc-shaped massing which is defined by open curves, translucence and permeability, and driven by sustainability principles to maximise natural ven la on in order to overcome the challenge of being surrounded by developments on all sides, including the Simtech Tower Block, Lee Wee Nam Library Tower, and the N2 and N3.2 Engineering Blocks. From the onset of the project, the close synergis c design development collabora on between the developer, architect and the engineers, and the builder, during the later stages, focused on safety, as well as on an elegant and buildable approach, to deliver the intended architectural outcome.

Loca on, plan and eleva on of the building. 18

THE SINGAPORE ENGINEER July 2019

The ARC is defined by open curves, translucence and permeability. Image by DCA Architects Pte Ltd /KIRK.

COVER STORY

Structural design to co-locate the building with an underground services corridor One of the key challenges in this project is the presence of exis ng underground (UG) live services, slicing through the building at the northwest corner. The iconic building’s curvilinear massing was driven by the need to have passive cooling and to pack in the required space programming of NTU Singapore, taking into account the height limit imposed by DSTA at 64 AMSL and exis ng building setback constraints on all sides. Careful considera on of the various op ons for structural transfers and the founda on support led to the development of a solu on that ensured the integrity and protecon of the underground services and their future-proofing, all at op mal cost. In addressing this challenge, various interac ve founda on-structure design solu ons, including long transfers, raking columns, and bored piles with e beams, were studied. In terms of the design collabora on process, design workshops with architects facilitated brainstorming for poten al solu ons.

Hand sketches were expedi ously translated into the digital Building Informa on Modelling (BIM) format, which contributed to high produc vity, as the client could make quicker decisions with the visualisa on informaon provided. Structural engineering analysis was then carried out using the finite element analysis so ware, ETABS, which eﬀec vely interfaced with the BIM model. In this con nuous eﬀort to iden fy a workable solu on to protect the exis ng services during construc on and in the post-construc on stages, the focus was on the founda on load path. The movement control and access safeguard became the cri cal focus in determining the design solu on. In conjuring up the founda on design solu on, the design philosophy was guided by the need to eliminate any poten al substructure es crossing orthogonally to the live services corridor. This was the future-proofing design driver to enable minimal encumbrances to the access to the services at all mes.

Curvilinear massing driven by passive cooling, in rela on to the live underground services corridor and nestled within dense, exis ng building setbacks.

Thinking out-of-the-box led to the innova ve use of a micropile group, enabling the founda on support to take eccentric moments via a push-and-pull lever arm within the micropile group itself. This ability of the micropile group to self-contain its stabilisa on needs enabled the realisa on of the live services corridor without the need to cross this corridor via cross e beams. On the execu on of the construc on, as the piling works for the western half of the building was on a steep slope with significant space constraints, a conscious design decision, driven by safety considera ons, was taken, which involved the use of micropiles instead of conven onal bored piles. The safety benefits were obtained from the construc on logis cs, as only smaller micropile machines had to be transported and posi oned. The decision proved to be insigh ul as the mobilisa on and opera on of the piling rigs on the slopes were made much simpler and safer, with the small micropile machines. In all, the final adop on of the group of micropiles allowed for a much more robust, future-proofed and safe solu on as compared to a single large diameter bored pile solu on.

Interoperability between the finite element analysis model and the BIM model.

The serious adop on of innova ve Building Informa on Modelling (BIM) and advanced Virtual Design and Construc on (VDC) technologies helped the team to realise a massing driven by the sustainable principle of passive cooling. With VDC technologies, the team was able to arrive at the eventual solu on, that is, placing the micropiles along both sides and within the services, eﬀec vely crea ng an undisturbed natural organic ‘corridor’ for the live services. The columns and fire escape core walls on the storey above the piles are transferred by means of transfer beams to the columns at the pile loca ons. It was possible to plan, with surgical precision, the structural transfer using micropiles, only because of the numerous trial holes bored at the early stages of design, to map the cables, and the adop on of innova ve VDC technologies to drive parametric studies in genera ng the most eﬃcient path of structural clearance away from the services, in the determina on of a robust transfer system. THE SINGAPORE ENGINEER July 2019

COVER STORY

Informa on from the 3D mapping of the cables ensured they would be a safe distance away from the piling and substructure works at every foreseeable loca on of the works. Throughout the construc on period for the project, there were no reported incidents of disrup ons to the cri cal UG services - a true testament of the results from the crea ve design of micropile groups with op mal

A 3D model showing the underground services (in red) at the northwest corner of the building and the specific se ng out of the various micropiles and substructures.

Site condi on and sec on showing the extent of excava on in the slope.

Eleva on of the CBP wall with two layers of ground anchors.

Concrete blocks created a safe access pla orm for the CBP installa on works. 20

THE SINGAPORE ENGINEER July 2019

setbacks, assisted by the meaningful deployment of VDC in achieving advanced safety management through visual planning and improving project understanding among the stakeholders, and subsequently enabling the predicted outcome for the substructure works.

Strutless and safe excava on system Since the Basement 4 ra was to be wedged within the 16 m high exis ng slope, it was necessary to provide an Earth Reten on Wall system to retain the soil from the Basement 4 founding level up to Basement 1 for both the temporary and permanent condi ons. The Earth Reten on Wall system had to be robust to prevent any poten al damage to all the four buildings surrounding the project and, importantly, to the cri cal live underground services at the top of the slope. With assurance from the preliminary risk assessment, that the excava on risk is manageable, the project adopted earth retaining and stabilising structures (ERSS) consis ng of Con guous Bored Piles (CBP) propped up by two layers of ground anchors (GA). The same CBP wall was designed to func on as both a temporary retaining wall and a permanent basement wall. The GA is designed at an inclina on of 45Â°. The excava on was carried out with two layers of temporary ground anchors, to achieve a safe robust excava on system. Most ERSS schemes involved in excava on to a 16 m depth would require stru ng but in this project, to keep the work site clear from obstruc ons that could pose working risks, a temporary ground anchor system was adopted. This mobilised the capacity of the retained soil in holding back the CBP and removed the need for any internal stru ng, thereby maximising safety within the work site as well as maximising construc on quality. The CBP walls are 1.2 m in diameter at 1.4 m c/c spacing. The CBP walls work in conjunc on with an engineered slope, up to 7 m at the top. This innova ve ERSS system opened up the en re basement area, without any single obstruc on, to allow the building works to progress in a safe manner. The u lisa on of a temporary ground anchor system allows for safe excava on and a shorter construc on me. The temporary ground anchors could be removed once successive lower floor slabs and beams were constructed. For CBP stability in the permanent stage, the lateral stability is restrained back with floor slabs and the beam of the building structure. Close monitoring of the pre-

COVER STORY

stressed grouted ground anchors installed in the soil, transmi ng the applied tensile load into the ground throughout the excava on and construc on period, un l the comple on of the roof construc on, was an important ac vity that contributed to the safety of the works. Various instrumenta on and monitoring devices were installed to ensure that the soil movements are controlled and the underground live services corridor is well protected. Apart from having a design that is robust, the considera on of logis cs was important in this project since Day 1. In order for the piling rigs to reach the level for installing the CBP, some form of temporary pla orm had

to be erected for access onto the slope. Concrete blocks were used due to their higher reliability and stability, as compared to soil backfill which is highly dependent on the quality of compac on. The stacking of the blocks was also pre-planned and visualised in the REVIT model to ensure the stacking was done in a systema c and organised manner. The en re basement excava on sequence had been modelled as part of a 4D approach, that is, the me dimension was included to ensure safety as the main objec ve throughout all stages in the design and construc on of this project. This innova on resulted in a systema c and smooth execu on of the construc on

4D simula on of the excava on works, to ensure clarity of stages and resource requirements.

Detec on of misalignments in the 4D model helped to ra onalise structural geometries, prior to actual construc on. THE SINGAPORE ENGINEER July 2019

COVER STORY

of this complex project, with all the team members acquiring a strong visual and quan ta ve understanding of the works. In addi on, the ability to have the en re work sequence rehearsed in 4D meant that the final product had minimal abor ve structural hacking works to resolve corners requiring three dimensional apprecia on of the adjacencies. The team’s 4D simula on helped to achieve a design that had minimal modifica on works during the construc on stage. The implementa on of VDC in this project was eﬀec ve in ra onalising the mul faceted structural geometries and streamlining the visualisa on, review and site construc on processes. This model was used to visualise construc on for safety or risk hazards, and it was possible to model in the safety measures to an appropriate level of detail required for the specific purposes of simula on, visualisa on, and safety briefings to the team.

earth loads from the high slope. The op ons were diligently studied with the adop on of Building Informa on Modelling (BIM) and advanced Virtual Design and Construc on (VDC) technologies to incorporate the underground services corridor into the design and construc on of the building whose loca on is defined by a naturally sloping topography. The thorough considera on given to all aspects of the project, and ac ve management, by the QP, hand-inhand with all the project stakeholders, throughout the design and construc on stages of the project, enabled safety and implementa on complica ons to be successfully tackled, thereby ensuring the safe comple on of a cost-eﬀec vely designed, buildable project.

Conclusion The ARC is an iconic learning hub nestled within a ght brownfield infill site and surrounded by exis ng buildings on all four sides. A curvilinear geometry characterises the superstructure massing which is driven by passive cooling considera ons. The design and construc on of the building presented significant challenges, par cularly due to the presence of mul ple, live underground cables suppor ng electrical, fire alarm and telecommunica on services embedded in the site which is located on top of a 16 m high slope that overlaps the superstructure. Working with great synergy, the team was able to achieve a future-proofed design via various interac ve founda on and structural design op ons, including long transfers, raking columns, bored piles and micropiles, in rela on to the permanent locked-in stresses due to the unbalanced

PROJECT CREDITS Qualified Person Er. Aaron Foong Kit Kuen C&S Consultant KTP Consultants Pte Ltd Builder Lian Ho Lee Construc on (Private) Limited Developer Nanyang Technological University Architectural Consultant DCA Architects Pte Ltd /KIRK

All images by KTP Consultants, unless otherwise stated.

A firm with a proven track record KTP Consultants was first established in 1969 as KT Philcox & Associates, by prominent British civil engineer, Mr Keith Thomas Philcox. With a track record in engineering and project management, established over these 50 years, KTP is today a brand synonymous with innovation and creative solutions for the built environment. Centred around the delivery of service excellence and efficiency, KTP has provided civil & structural engineering solutions for many award-winning projects including Oasia Hotel Downtown Singapore, The Scotts Tower and Heartbeat@Bedok. In 2015, KTP joined the Surbana Jurong Group. Headquartered in Singapore and wholly-owned by Temasek Holdings, Surbana Jurong is one of the largest Asia-based urban, infrastructure and management services consulting firms. The group has a global workforce of over 16,000 employees in more than 120 offices across over 40 countries in Asia, Australia, UK, the Middle East, Africa and the Americas. The Surbana Jurong Group includes SMEC and Robert Bird Group, in Australia; Sino-Sun, in China; AETOS, KTP and SAA, in Singapore; and B+H, in Canada. Surbana Jurong has a track record of close to 70 years, and has built more than a million homes in Singapore, crafted master plans for more than 30 countries and developed over 100 industrial parks globally.

THE SINGAPORE ENGINEER July 2019

CIVIL & STRUCTURAL ENGINEERING

NUMERICAL MODELLING OF NATM AND UNDERPINNING WORKS

UNDERNEATH AN EXISTING UNDERGROUND MRT STATION by N H Osborne, S Ashokvardhan and A Yang, Mo MacDonald Singapore Pte Ltd, Singapore; and C L Liew and C K Toh, formerly with Mo MacDonald Singapore Pte Ltd, Singapore In a Southeast Asian city, an exis ng deep underground Mass Rapid Transit Sta on has a piled ra founda on in residual soil overlaying completely weathered grani c rock. The founda on will be subjected to future complex underground connec on development underneath the exis ng sta on pla orm. At the me of temporary works feasibility study, an empirical method of predic ng the soil and pile springs was used for analysis. The s ďŹ&#x20AC;ness of the soil-pile-ra system was reflected in the assumed compressibility of the spring-shell in a 3D finite element structural model. This yielded an unrealis c predic on of induced forces in the exis ng piles and ra , far exceeding the exis ng structural capaci es of the slab as compared to the exis ng opera onal condi on of the sta on base slab. This renders the future underground connec on development below the slab impossible. This ar cle describes the use of the 3D geotechnical finite element method to model the exis ng sta on piled-ra founda on as a separate assessment on forces and se lement predic on. A comparison is made between the 3D geotechnical and structural finite element method to get a fair agreement on predic ng the exis ng condi on of sta on piled ra founda on and its behaviour if subjected to the future underground connec on development.

1 INTRODUCTION A deep underground Mass Rapid Transit (MRT) station was one of the major MRT stations in a Southeast Asian city in circa 1970. In the early 21st century, an iconic commercial development was constructed right above the station, transforming the station into one of the most connected stations in the city. To keep up with the ever-growing public transportation demand and spur better connectivity between existing MRT lines and future MRT lines, the station was designated as one of the potential interchange MRT stations. A future MRT station will be connected to the station via a paid-access-link (PAL) which will be located underneath the existing station platform. This was an innovative approach to create underground space usage for public connectivity in a densely built-up commercial area in the city where land scarcity is a challenge. The PAL design is a challenge for the construction and temporary works design team. This is because the PAL has to be constructed underneath the existing sensitive station platform with minimal disruption to the live operational MRT assets and the iconic commercial building. The New Austrian Tunnelling Method (NATM) will be used for PAL construction. A 3D geotechnical FEM software, PLAXIS 3D AE, was used to carry out analyses to predict the existing station platform and foundation conditions before the construction of the PAL, and the behaviour of the plat-

form and foundation during PAL construction. These 3D soil-structure interactions could not be realistically modelled by 2D geotechnical FEM or 3D structural FEM software. This article will detail the lessons learnt in using PLAXIS 3D to assess the existing forces in the station platform and foundation, and to carry out impact assessment on the platform slab and foundation due to the PAL construction using NATM.

2 GROUND CONDITION The project area is underlain by the residual soil and completely weathered granitic rock. In general, the soil profile starts with approximately 4 m of fill, underlain by residual soils of the granitic rock formation and completely weathered granitic rock. The residual soil from 106 mRL to 79 mRL has an SPT-N value in the range between 20 and 35. Below 79 mRL, the completely weathered granitic rock has an SPT-N value in the range between 40 and 55. The ground water table at site is approximately 5 m to 10 m below the existing ground level surface. The existing station has an active pumping system which is pumping out water from the base slab continuously. From the site water standpipe reading, the water level record indicated that the ground water level is relatively stable. It can therefore be hypothesised that the underground water flow regime has been stabilised by the active water pumping system. THE SINGAPORE ENGINEER July 2019

CIVIL & STRUCTURAL ENGINEERING

3 MINED TUNNELLING UNDERNEATH AN EXISTING DEEP UNDERGROUND MRT STATION

in the top heading is 1.5 m with a minimum of 9 m lagging between Drive 1, Drive 2 and Drive 3. In order to enhance the stability of the excava on face, face nails will have to be pre-installed before each advance.

3.1 KEY PROJECT CHALLENGES

As the tunnel will be constructed underneath the pla orm of the opera ng MRT sta on, the soil below the slab will be excavated sequen ally and micropiles will be installed to underpin the pla orm. Jacks will be installed in between the top of all micropile heads and invert of the pla orm slab to control and prevent se lement of the en re MRT sta on. The installa on of the underpinning micropiles and jacks will be carried out sequen ally a er each top heading advance. Upon comple on of top heading and underpinning micropiles, the invert excava on will be carried out sequen ally un l comple on of the mined tunnel.

3.2 NATM SUPPORT DESIGN AND CONSTRUCTION SEQUENCE

Figure 1: Typical mined tunnel sec on.

Invert

Top Heading

The mined tunnel is to be approximately 14.3 m in width and 7.8 m in height. It is envisaged to be constructed using NATM and supported by steel wire mesh sprayed concrete lining and temporary soil nails. The typical mined tunnel sec on can be referred to in Figure 1, while cross sec ons of the mined tunnel are shown in Figure 2. The envisaged mining sequence can be referred to in Figure 3. The sequence of excava on and support comprises a top heading with temporary invert and bench excava on. The top heading is sub-divided into three dri s, namely Drive 1, Drive 2 and Drive 3, and the bench is to be excavated in one drive, namely Drive 4. The maximum advance length

Top Heading

The project site is located underneath an exis ng live MRT sta on that is supported by a piled ra founda on. The main challenge of this project is to control the movement of the sta on slab and to fulfil the stringent criteria set by the local land transport authority. There is an iconic commercial building adjacent to the project and it is par ally connected to the sta on via an underground passenger network link.

Figure 2: Cross sec on of mined tunnel top heading and invert.

Figure 3: Envisaged top heading and invert mining sequence. 24

THE SINGAPORE ENGINEER July 2019

CIVIL & STRUCTURAL ENGINEERING

3.3 3D FEM MODELLING ASSUMPTIONS For the PLAXIS 3D modelling, several assump ons are made and elaborated, as follows: 3D FEM cons tu ve soil models • All soil layers are modelled as a Hardening-Soil Model (HSM) and in a drained condi on. • HSM is an advanced soil model that circumvents the shortcomings of Mohr-Coulomb, such as ignoring the non-linear and inelas c behaviour of soil, and assuming a constant modullus of soil, regardless of changes in the confining pressure. HSM is an elastoplas c type of soil model which is able to consider compression hardening to simulate irreversible compac on of soil under primary compression. • As highlighted by Schanz T et al (2000), HSM is be er in simula ng the behaviour of sand and clay that does not exhibit strong anisotropy. • The ground improvement block is modelled as a Mohr-Coulomb soil model and in a non-linear condi on. • Steady-state flow analysis is considered in the water flow calcula on to generate pore water pressure. Ground condi on • All soil layers are modelled as drained. • Due to the ac ve pumping system of the sta on, the groundwater table within the sta on is assumed to be below the soﬃt of the ra to eliminate the benefit of hydraulic upli onto the ra . • The groundwater table, apart from the sta on base, is assumed to be at the exis ng ground surface level. • A 20 kPa surface load is considered as the road surcharge.

Figure 4: PLAXIS 3D model.

The sta on ra is modelled as a plate element. Conserva vely, the s ﬀness of the structural elements above the ra is not considered. The exis ng se lement reducing piles under the centre and perimeter of the ra are modelled as embedded beam elements. Figure 4 shows the developed PLAXIS 3D model, based on the as-built drawings of the MRT sta on and surrounding geological profile and ground condi on. For the structural capacity checks on the sta on base slab, these are done by analysing the forces and moments in the plate. The forces and moments are then checked against a 3D structural model for a fair agreement with the results computed by the sophis cated 3D FEM geotechnical model. The checking is detailed in Sec on 4.1.

Structure loads • The iconic commercial building and sta on structure loads are applied onto the ra as point loads.

3.5 3D FEM MODELLING OF NATM CONSTRUCTION SEQUENCE UNDERNEATH STATION UNDERPLATFORM

• The weights of the MRT locomo ves is applied on the ra as surface loads.

Further, from the PLAXIS 3D model, as described in Secon 3.4, the analysis and predic on of induced slab vercal movement, forces and moments, due to the NATM construc on sequence, are modelled. The aim is to simulate soil-structure interac on and analyse the plate behaviour during sequen al excava on using NATM. The induced ver cal movement, forces and moments are studied. The study result is detailed in Sec on 4.2.

3.4 3D FEM MODELLING OF EXISTING MRT STATION PLATFORM AND FOUNDATION For the analysis and predic on of the exis ng condi on of the MRT sta on piled ra founda on, a sophis cated 3D FEM geotechnical so ware, PLAXIS 3D, capable of handling complex soil-structure interac on, is adopted. The main characteris c of PLAXIS 3D is the modelling of advanced 3D geometries and meshes, soil elements and structure elements, such as beam, pile and plate. The mul -staged construc on feature in PLAXIS 3D enables 3D modelling of sequen al excava on by NATM, which is crucial in this aspect of analysis. The geotechnical model is set up in PLAXIS 3D by assuming linear interpola on of soil stra fica on. Soil behaviour is characterised using HSM, as men oned in Sec on 3.3.

As described in Sec on 3.2, the top heading is sub-divided into three dri s, namely Drive 1, Drive 2 and Drive 3. For each mining stage, the typical advance is 1.5 m and the mining face and side walls will be excavated in a gradient of 5:1. Immediately a er each stage of mining, sprayed concrete lining will be applied on the exposed side walls, soil nails will be installed sequen ally, and underpinning piles will be installed sequen ally to support and minimise the sta on platform ver cal movement. Figure 5 shows the envisaged mul -drive and two-direc onal top heading and invert mining sequence. THE SINGAPORE ENGINEER July 2019

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Figure 5: Envisaged top heading mining with underpinning works and invert mining sequence.

Figure 8: Shear force Q13 at the MRT sta on base slab (from PLAXIS 3D).

Figure 6: Ver cal displacement at the MRT sta on base slab (from PLAXIS 3D).

Figure 9: Bending moment M22 (sagging and hogging) at the MRT sta on base slab (from 3D structural model).

Figure 7: Bending moment M22 (sagging and hogging) at the MRT sta on base slab (from PLAXIS 3D)

To ensure minimal water pressure build up around the mined tunnel primary support, the sprayed concrete lining is designed to be non-water-bearing. Water is allowed to seep through the shotcrete and is collected into a temporary sump pit. The water will be pumped out of the mined tunnel and discharged appropriately.

4 ANALYSES AND RESULTS 4.1 EXISTING STATION PLATFORM AND FOUNDATION For the exis ng condi on before mining works, the PLAXIS 3D results, in terms of displacement, forces and moments of the plate, are presented in Figure 6 to Figure 8. Figure 9 and Figure 10 refer to the bending moment (M22) and shear force (Q13) from the 3D structural model, respec vely. The results are shown only at the end of the phase of applying loads from the iconic commercial building and sta on. 26

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Figure 10: Shear force Q13 at the MRT sta on base slab (from 3D structural model).

Comparing the forces and moments from the PLAXIS 3D plate and that of the 3D structural model, it is observed that both models have predicted bending moments and shear force contours of comparable magnitude. By analysing the ver cal displacement contour of the plate in PLAXIS 3D model, it is predicted that the exis ng sta on pla orm is well within the stringent angular distor on limit of 1:1666, as set by the local land transport authority. Referring to the axial force of individual founda on piles, it is no ced that average mobilisa on of the piles is approximately 68%. Furthermore, the result also suggests that the total structure loads taken by the piles and

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slab are approximately 28% and 72%, respec vely. This indicates that PLAXIS 3D is capable of simula ng complex soil-pile-structure interac ons of a piled ra founda on.

4.2 STRUCTURAL 3D ANALYSIS The MRT sta on is set up in SAP2000 as per the asbuilt drawings kept since the 1980s. The 3D structure is modelled using shell elements while the soil beneath the sta on slab, exis ng piles and underpinning piles are modelled using springs. The springs are derived from the piles’ s ﬀness and subgrade moduli, using PLAXIS 3D analyses results. The mining and underpinning pile installa on are simulated in non-linear staged construc on analyses to compute the the slab’s internal forces during each mining stage and underpinning piles installa on.

Figure 13: Induced shear force Q13 in the sta on base slab at the end of the top heading mining and underpinning works (from PLAXIS 3D).

4.3 BEHAVIOUR OF STATION UNDERPLATFORM AND FOUNDATION DURING NATM SEQUENTIAL EXCAVATION The PLAXIS 3D results of NATM sequen al excava on, in terms of displacement, forces and moments of the plate, are presented in Figure 11 to Figure 13. Figure 14 and Figure 15 can be referred to for bending moment (M22) and shear force (Q13), from the 3D structural model, respec vely. The results are only shown at the end of the top heading excava on phase.

Figure 14: Induced bending moment M22 (sagging and hogging) in the MRT sta on base slab at the end of the top heading mining and underpinning works (from 3D structural model).

Figure 11: Induced ver cal displacement of the MRT sta on base slab at the end of the top heading mining and underpinning works (from PLAXIS 3D).

Figure 12: Induced bending moment M22 (sagging and hogging) in the MRT sta on base slab at the end of top heading mining and underpinning works (from PLAXIS 3D).

Figure 15: Induced shear force Q13 in the MRT sta on base slab at the end of the top heading mining and underpinning works (from 3D structural model). THE SINGAPORE ENGINEER July 2019

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Figure 16: Longitudinal diﬀeren al se lement of the MRT sta on base slab.

Figure 18: Ver cal eﬀec ve stress before top heading mining.

Figure 17: Transverse differential settlement of the MRT station base slab.

For differential settlement calculations, longitudinal and transverse lines are defined, corresponding to the direction of platform (Figure 16 and Figure 17). Based on the calculations, the predicted vertical movement of the platform induced by NATM sequential excavation is well within the stringent differential settlement of 1:1666, as set by the local land transport authority. Comparing the induced forces and moments due to the NATM sequential excavation in PLAXIS 3D plate and in the 3D structural model, it is observed that the 3D structural model shows drastic changes of forces and moments, especially at highly loaded areas. In contrast, the plate from PLAXIS 3D shows smoother transition and a minimum of drastic changes of forces and moments. This is likely due to compression hardening in HSM, providing vertical support during each stage of excavation. Figure 18 and Figure 19 present the comparison between vertical effective stresses before and after mining. From the vertical effective stress contours (before and after mining), it is observed that the soil (dark blue) around the mining zone has been disturbed and the station base slab loads are being transferred to the adjacent soil (light blue). Another interesting observation is that the arching effect surrounding the mining zone, which further amplifies the convergence behaviour, is being reflected in the PLAXIS 3D FEM analysis. Figure 20 and Figure 21 can be referred to for the longitudinal and sectional views, respectively, of the effective principal stresses surrounding the mining zone. The results suggest that the sophisticated soil-structure interaction behaviour during NATM sequential excavation is well captured in PLAXIS 3D but not in the 3D structural model which relies heavily on simplified pile and soil spring modification at each stage of the excavation. 28

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Figure 19: Ver cal eﬀec ve stress during top heading mining.

Figure 20: Longitudinal view of the eﬀec ve principal stresses surrounding the top heading mining zone.

Figure 21: Sec onal view of the eﬀec ve principal stresses surrounding the top heading mining zone.

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5 RECOMMENDATIONS Based on the above-men oned numerical modelling study, using 3D FEM geotechnical so ware, PLAXIS 3D, there are a few topics to be inves gated and studied further, while carrying out the complicated FEM analysis: • Soil shear strength mobilisa on during cri cal mining stages. • Effects of soil s ffness on the subgrade modullus values for 3D structural model inputs. • Effects of underpinning piles’ s ffness on the sta on base slab ver cal displacement, internal forces and induced moments during mining. • Effects of ground improvement strength and s ffness on the soil convergence during mining.

Bentley Systems acquires Plaxis and SoilVision

6 CONCLUSION

Projects begin with geotechnical surveys and sampling, captured with gINT, for documenta on and repor ng. Next, professionals perform engineering related to soil proper es, soil behaviour and groundwater flow, using SoilVision’s SVOFFICE applica ons, supplemented by Plaxis’ oﬀerings. Then soil-structure interac on is analysed through Plaxis’ design, simula on, and engineering so ware, such as PLAXIS 2D and PLAXIS 3D.

This ar cle presents a method to predict the forces, moments and se lement of the sta on base slab, before and a er mining excava on and underpinning piles installa on directly below the slab. The cons tu ve soil model, HSM, in PLAXIS 3D, is able to simulate the relaxa on behaviour and arching eﬀect during mining in the residual soil. The induced forces and moments in the slab, predicted in PLAXIS 3D, are also comparable to that from the 3D structural model, not to men on that it is more realis c due to the sophis cated soil-structure interac on in the 3D geotechnical FEM model. It is noted from the FEM analyses that the impact assessment due to mining directly underneath the sta on base slab as well as assessment of the damage to the integrity of the exis ng structure during and a er the mining works have been carried out and are es mated to be within tolerable limits, as per the design criteria of the local land transport authority. This result can be achieved only with the provision of massive ground improvement works before the mining and underpinning works are carried out sequen ally a er each mining step. The sophis cated 3D FEM analyses are vital for such a complex NATM sequen al excava on, considering the mul -drives and two-direc onal mining and underpinning works. At the me of wri ng the technical paper on which this ar cle is based, the design of the mined tunnel had been approved by the local building control authority and construc on of the PAL using the NATM, as described in this ar cle, had just commenced. The construc on and performance of the NATM tunnel will be covered in a separate technical paper a er comple on of the PAL.

In late April 2018, Bentley Systems Inc, a leading global provider of comprehensive so ware solu ons for advancing infrastructure, announced the acquisi on of Plaxis, a leading provider of geotechnical so ware, based in Del , Netherlands, and the agreement to acquire soil engineering so ware provider SoilVision, based in Saskatchewan, Canada. The acquisi ons, with Bentley’s market-leading borehole repor ng and data management so ware gINT, serve to make Bentley a complete source for geotechnical professionals ‘going digital’. As a result, BIM advancements can be extended to the subsurface engineering of every infrastructure project.

The new opportunity, by way of digital workflows enabled through Bentley’s comprehensive modelling environment, is for geotechnical applica ons to be integrated with Bentley’s structural applica ons (such as STAAD, RAM, and SACS) for improved geostructural engineering performance. As changes may occur in owner requirements, structural strategies, or site condi ons (con nuously surveyed through UAVs and Bentley’s ContextCapture for reality modelling), geotechnical analysis could be con nuously applied for improved outcomes, as managed through ProjectWise collabora on services. For today’s infrastructure demands, geotechnical considera ons are coming to the fore. Urbanisa on, for instance, drives growth both ver cally and underground, with emphasis on the capacity of founda ons and tunnels. And new infrastructure projects of every type depend upon constructed dams, embankments, dykes, levees, and reservoirs, to improve their resilience.

ACKNOWLEDGEMENT Permission by Bachy Soletanche and Singapore Land Transport Authority to present the analysis study is gratefully acknowledged. REFERENCE [1] Schanz T, Vermeer P A and Bonnier P G: ‘The hardening soil model: formula on and verifica on’, Beyond 2000 in Computa onal Geotechnics - 10 Years of PLAXIS 1999 Balkema, Ro erdam, The Netherlands.

PLAXIS 3D performs three-dimensional analysis of deformation, soil-structure interaction, and stability in geotechnical engineering and rock mechanics.

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CROSS PASSAGEWAY SPACING PROVISION FOR

RAILWAY TUNNELS by Dr Cheong M K, Er. Lim L W, Er. Melvyn Thong and Dr Samuel Chan, Land Transport Authority of Singapore The cri cal factors considered in a study that was undertaken and the results are presented.

INTRODUCTION In most rail transit fire and life safety standards where provision of cross-passageways is permi ed in lieu of emergency exit stairways, the maximum distance between cross passageways is prescribed. Fire and life safety standards such as NFPA 130, ‘Standards for Fixed Guideway Transit and Passenger Rail System’ [1] s pulates that where cross-passageways are u lised in lieu of emergency exit stairways, the distance between cross-passageways shall not be more than 244 m. Singapore’s Code of Prac ce for Fire Precau ons in Rapid Transit System (CPFPRTS) s pulates the requirement that the maximum spacing between cross-passageways, which are considered points of safety, shall not be more than 250 m [2]. In Germany and Switzerland, the spacing between emergency exits must not be greater than 500 m [3]. However, in France, where parallel escape tubes are available, cross-passageways must be provided with a maximum spacing between them of 800 m [3]. Hong Kong has similar tunnel cross-passageway requirements as NFPA 130 [4]. In the United Kingdom, the maximum spacing between cross-passageways is determined based on train length, the method of evacua on and the needs of the emergency services [5]. The maximum cross-passageway spacing therefore varies depending on the standard that the designer adopts. The basis on which the maximum cross-passageway spacing is established is not clear. In rail tunnel projects, the provision of cross-passageways along the tunnel alignment may some mes pose challenges to the designers, due to site constraints. If the designer is to refer to the various standards for guidance, he/she may be confused with the diﬀerent maximum spacing requirements for cross-passageways in the standards. This ar cle a empts to provide some guidance on the cri cal factors to be considered when determining the spacing between cross-passageways.

Figure 1: Tunnel evacua on strategy during tunnel fire.

Figure 2: Underground trainway.

EMERGENCY EVACUATION STRATEGY During a train fire incident in the tunnel, the primary objec ve is to ensure the safe evacua on of the passengers. Where possible, the incident train should be brought to the next sta on where evacua on of passengers on-board the incident train - and rescue and fire-figh ng opera ons - would be quicker and easier. At the sta on, the passengers onboard the incident train can evacuate directly onto the sta on pla orm using the side doors of the train and open pla orm screen doors (PSD), if provided. If the incident train on fire is 30

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Figure 3: Emergency egress pathway in underground trainway.

unable to proceed to the next sta on, the passengers will have to disembark from the train onto the tunnel and move towards the point of safety, which could either be a cross-passageway or escape staircase (Figure 1). To ensure that the passengers can evacuate safely, a tenable environment will have to be maintained along the egress

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METHODOLOGY AND DESIGN CRITERIA

Figure 4: Signage in tunnel (XPESS and ITESS).

For this study, the methodology adopted for evalua ng the adequacy and provision of cross-passageways for passenger evacua on from a train on fire in the tunnel is to determine both the available safe escape me (ASET) and required safe escape me (RSET) and then check to ensure that ASET is larger than RSET. This will ensure that the evacuees are able to evacuate safely before the condi on in the incident tunnel becomes untenable. The Fire Dynamics Simulator Version 6.5.3 (FDS), which is a computa onal fluid dynamics (CFD) so ware developed by the Na onal Ins tute of Standards and Technology (NIST) [6], was used to determine the ASET. The evacua on simula on so ware, Pathfinder [7], was used to determine the RSET which includes the response me of the operator and evacuees plus a safety factor of 2. The following acceptance criteria [2] were used to assess the tenability of the environment along the egress route in the tunnel during a train fire incident: Heat eﬀects (temperature) Table 1 gives the maximum exposure me without incapacita on for lightly clothed evacuees when exposed to diﬀerent temperatures.

Figure 5: End-detrainment door evacua on.

path and this is generally achieved by opera on of the emergency tunnel ven la on system. Other than opera ng the tunnel ven la on system, it is necessary also to halt all other trains, cut-oﬀ the trac on power supply, and switch on the emergency tunnel ligh ng system, the Illuminated Tunnel Evacua on Signage System (ITESS) and the Cross Passage Signage System (XPESS) - in the aﬀected tunnel sec ons(s) - before commencement of passenger evacua on to the point of safety. The CPFPRTS requires that the egress pathway has a minimum width of 0.8 m (Figure 3) and an unobstructed access to the cross-passageways. ITESS and XPESS are also required to facilitate the emergency evacua on of passengers (Figure 4). For the Singapore metro system, the trains are provided with end-detrainment doors for passengers to evacuate from the incident train onto the track bed and then proceed to the cross-passageway or exit staircase during an emergency (Figure 5). As the signalling system allows a maximum of two trains in a tunnel sec on between two sta ons, the presence of a non-incident train stalled within the same tunnel sec on may pose an obstacle to evacua ng passengers. This issue is addressed by providing a low height walkway along the length of the tunnel. The passengers a er disembarking from the incident train can climb up the walkway to bypass the non-incident train before proceeding to the cross-passageway or exit staircase. For metro systems that use the side doors of trains for evacua on, the presence of a non-incident train will not have the same issue, as the passengers from the incident train can disembark directly onto the walkway in the first instance.

Maximum Exposure Time Without Incapacita on (minutes)

4.5

10.7

Exposure Temperature (˚ C)

78.8

Table 1: Maximum exposure me without incapacita on.

Smoke obscura on levels Smoke obscura on levels should be maintained below the point at which a sign internally illuminated is discernible at 30 m and doors and walls are discernible at 10 m. Air carbon monoxide content The maximum carbon monoxide exposure limits are as follows: • Maximum of 2000 ppm (parts per million) for a few minutes. • Averaging 1500 ppm or less for the first 6 minutes. • Averaging 800 ppm or less for the first 15 minutes. Air velocity The air veloci es in the tunnel should not be greater than 11 m/s.

COMPUTATIONAL FLUID DYNAMICS ANALYSIS CFD simula ons using FDS were performed to evaluate the environmental condi ons in the tunnel during a train fire. The computa onal domain, comprising a tunnel of 5.6 m diameter with a walkway and third rail for supplying power to the trains, and two trains spaced 40 m apart within the same tunnel sec on, was modelled. Three diﬀerent train configura ons, each comprising 3, 4 and 6 carriages, were studied. Each carriage measured approximately 23.3 m in length, 2.58 m in width and 3.7 m in height. A mul ple computa onal domain with a grid size THE SINGAPORE ENGINEER July 2019

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of 0.3 m was used to construct the tunnel model. Figure 6 shows the sec onal view of the tunnel. For all the scenarios studied, a fire was assumed to have ignited below the floor of one of the end carriages of the train, which then burned through the floor and subsequently spread to the rest of the carriages. FRP Polyester, which is the predominant material used for the train carriage finishes, was selected as the combus ble material for the simula ons. Figure 7 shows the development curves for the fires involving trains with 3, 4 and 6 carriage configura ons. From Figure 7, it can be seen that the rate of rise and peak heat release rate during the growth phase of the fires are similar for all three train carriage configura ons. However, the total dura on of burning is longer for the train with more carriages. This is not unexpected as trains with more carriages will have more carriages involved in the burning process and therefore the energy release will be larger and burning dura on will be longer [9].

Results of the CFD analyses show that if the achieved longitudinal air velocity in the incident tunnel is higher than the cri cal velocity, the condi on along the egress path will remain tenable. Since the tunnel ven la on fans are capable of opera ng in an airstream temperature of 250Â° C for 2 hours, it can therefore be assumed that the ASET will also be 2 hours. Figure 8 shows the air temperature, visibility, CO concentra on and velocity profiles in the incident tunnel at 1200 seconds a er igni on of fire at the rear of the incident train. The air temperature, visibility and air velocity in the tunnel sec on upstream of the incident train on fire (which is the egress path) at 1200 seconds a er igni on of fire all met their respec ve criterion for tenability. When the CO concentra on level falls below 0.7 x 10-3 mol/ mol (that is, blue zone in the CFD results), the CO concentra on will be less than 800 ppm. Since the CFD results indicate that the CO concentra on is less than 800 ppm, the CO concentra on criterion for tenability is also met.

Figure 6: Tunnel cross sec on.

Figure 7: Heat release rate for diďŹ&#x20AC;erent train carriage configura ons.

CFD tunnel fire simula on results For this study, CFD analyses were performed using FDS to examine the environmental condi ons in the incident tunnel during a train fire incident with the Tunnel Ven la on System (TVS) in opera on. One of the limita ons is that only two trains within a ven la on zone were considered in this study. This is a probable and controllable scenario through the train signalling system. Although analyses have been performed for fires involving trains with 3, 4 and 6 carriage configura ons, only the results for fires involving a train with 6 carriages at 120 minutes are presented in this ar cle. 32

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Figure 8: CFD results for rear train fire.

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Figure 9: CFD results for rear train fire.

EVACUATION ANALYSIS USING PATHFINDER This sec on describes the evacua on analysis performed to es mate the RSET, that is., how long all the evacuees from the incident train on fire in the tunnel will take to reach the point of safety, that is, the cross-passageway. The evacua on simula on tool, Pathfinder [7], was used for the analysis. For the evacua on analysis, the model used was a bored tunnel with third-rail and a walkway along the tunnel similar to that for the CFD analyses (Figure 9). Table 2 gives a summary of the parameters adopted for the evacua on simula ons. Figure 10 shows the evacua on me-line assumed for determining the RSET, which includes the mes taken for detec on of the fire, verifica on of fire and response by the staﬀ in the opera on control centre (OCC), and pre-movement and movement of the passengers in the incident train on fire.

in Figures 11 to 16. Only the evacua on results for a train with 6 carriages is presented in Table 3.

Figure 10: Evacua on meline. Descrip on

Simula on parameters

Train carriage length (m)

23.3

Train carriage width (m)

2.58

Tunnel evacua on simula on results

End detrainment door width (m)

1.2

This sec on presents the results of the tunnel evacua on simula ons, using Pathfinder, for different cross-passageway spacing, walkway width and number of carriages per train. This study assumes that the passengers evacuate from the incident train using the end-detrainment door. A total of 72 different evacua on scenarios were simulated. The evacua on mes and RSET computed for incident trains with 3-, 4- and 6-carriage configura ons, different walkway widths and cross-passageway spacing are shown

Cross-passage door width (m)

Walkway width (m)

Number of passengers per carriage

224

Number of carriages per train – varies

3,4 and 6

Walkway width (m) – varies

0.8, 1, 1.2, 1.4

Cross-passage doors intervals (m) - varies

50, 100, 150, 200, 250, 300

Passengers walking speed (m/s)

1.1

Safety factor for RSET

Table 2: Evacua on simula on parameters.

Cross-passageway spacing (m) 50 m

100 m

150 m

200 m

250 m

300 m

Evac (mins)

RSET* (mins)

Evac (mins)

RSET* (mins)

Evac (mins)

RSET* (mins)

Evac (mins)

RSET* (mins)

Evac (mins)

RSET* (mins)

Evac (mins)

RSET* (mins)

0.8

24.75

73.50

30.72

85.44

31.68

87.36

35.78

95.56

38.20

100.40

43.58

111.16

1.0

24.88

73.76

26.43

76.86

30.30

84.60

30.70

85.40

35.53

95.06

39.68

103.36

1.2

24.45

72.90

25.63

75.26

27.90

79.80

30.00

84.00

32.92

89.84

39.43

102.86

1.4

24.00

72.00

25.38

74.76

27.65

79.30

29.98

83.96

32.53

89.06

39.36

102.72

Note: RSET* = RSET x a safety factor of 2. Table 3: Evacua on simula on results for a train with 6 carriages. THE SINGAPORE ENGINEER July 2019

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Figure 11: Time for passengers to reach cross-passageway. Figure 15: Time for passengers to reach cross-passageway.

Figure 12: RSET vs cross-passageway spacing.

Figure 16: RSET vs cross-passageway spacing.

DISCUSSION OF RESULTS Based on the above results, the following observa ons can be made:

Figure 13: Time for passengers to reach cross-passageway.

Figure 14: RSET vs cross-passageway spacing. 34

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• The criteria for a tenable environment, such as temperature, visibility, CO concentra on and velocity, can be met along the evacua on path in the incident tunnel sec on during the first 2 hours of fire development, as shown by the CFD simula on results in Figure 8. A dura on of 2 hours has been used for assessing the tenability criteria because, for this study, the tunnel ven la on system equipment has been assumed to be capable of operating in an airstream temperature of 250° C for a dura on of 2 hours. For scenarios where the evacua on me, or RSET, is longer than 2 hours, the temperature ra ng of the tunnel ven la on system equipment should be reviewed as part of the fire and life safety analysis. • The cross-passageway spacing has significant impact on the evacua on me, that is, the me for the passengers to evacuate to a point of safety. This can be seen in Figure 17 which shows the increase in evacua on mes for diﬀerent cross-passageway spacing rela ve to those for a 50 m cross-passageway spacing, for trains with 3, 4 and 6 carriage configura ons. The results show that the evacua on me increases as the cross-passageway spacing is increased.

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Figure 17: Factor increase in evacua on me.

• In general, there are merits of providing a wider walkway in tunnels if the spacing between cross-passageway is increased. A wider walkway will allow the faster moving passengers to overtake the slower passengers during evacua on (see Figures 11, 13 and 15). For example, the me taken for passengers to evacuate from a train with 6 carriages in a tunnel with 250 m cross-passageway spacing can be reduced by 5.28 minutes if the width of the walkway is increased from 0.8 m to 1.2 m. However, it is also observed the increase in walkway width will not reduce the evacua on me significantly for a scenario where the cross-passageways are spaced at very close intervals such as 50 m. This is because the closely spaced cross-passageways will allow the passengers from the incident train to evacuate using the end-detrainment door to the nearest cross-passageway quickly without the need to use the walkway to move around the obstruc ng non-incident train to the cross-passageway. • For scenarios where the fire occurs at the train under-carriage, it is important that the floor of the train carriages is able to prevent the fire from spreading into the saloon so that all the passengers can escape from the incident train before the floor caves in or becomes unstable for the passengers to traverse during train evacua on. In most modern transit trains, a 45 to 60 minutes’ fire barrier is provided between the undercarriage and the saloon. The fire ra ng proper es of the floor will prevent the temperature of the floor from exceeding cri cal levels. The results in Figures 11, 13 and 15 indicate that for train passenger evacua on using the end-detrainment doors, the evacua on me increases as the number of train carriages increases. The number of carriages should be considered when determining the fire ra ng provision for the train floor. For example, the me taken for passengers to evacuate from a 6-carraiage train is 35.9 minutes. This is close to the 45 minute fire ra ng requirement of the floor of a typical modern transit train. The fire ra ng requirement for the train floor should be assessed for trains with more than 6 carriages.

CONCLUSION In conclusion, this study provides an insight on the permissible spacing for cross-passageways in a rail transit tunnel for safe evacua on of passengers during a train on fire in the tunnel, using a performance based-approach. It also demonstrates that using a performance-based approach will allow the designers to provide a safer and more cost-eﬀec ve design from a fire and life safety perspec ve. REFERENCES [1] ‘NFPA 130: Standard for Fixed Guideway Transit and Passenger Rail Systems’, 2014 Edi on, Massachuse s, Na onal Fire Protec on Associa on, USA. [2] ‘Code of Prac ce for Fire Precau ons in Rapid Transit System’, 2017 Edi on, Singapore Civil Defence Force. [3] P Sco et al: ‘Fire in Tunnels: Technical report part 2, Fire Safe Design - Rail Tunnels’, European Thema c Network Fire in Tunnels. [4] ‘Guidelines on Formula on of Fire Safety Requirement for New Railway Infrastructures’, Hong Kong Fire Service, January 2013. [5] ‘Railway Safety Principles and Guidance’, Oﬃce of Rail Regulaon, UK, 2006. [6] McGra an K and Forney G: ‘Fire Dynamics Simulator (Version 6) User’s Guide’, Na onal Ins tute of Standards and Technology, Gaithersburg, MD, USA, 2013. [7] ‘Pathfinder User Manual’, Thunderhead 2016. [8] Karl Fridolf, Daniel Nilsson, Hakan Frantzich: ‘Evacua on of a Metro Train in an Underground Rail Transporta on System: Flow Rate Capacity of Train Exits, Tunnel Walking Speeds and Exit Choice’, Fire Technology, Volume 52, Issue 5, pp 1481 - 1518, September 2016. [9] M K Cheong, P R Handojo, L W Lim, M Thong, K W Leong: ‘Heat Release Rate Es mate for Metro Train Fire in Rail Tunnel’, Fire Safety and Emergency Management Conference, Singapore, October 2011. [10] ‘Singapore Fire Safety Engineering Guidelines’, Singapore Civil Defence Force, 2015. THE SINGAPORE ENGINEER July 2019

RAILWAY & ROAD ENGINEERING

A HIGH PERFORMANCE COLD RECYCLER FOR THE STRUCTURAL REHABILITATION OF ROADS The advantages oﬀered include lower consump on of materials such as binders, faster comple on of projects, and sustainability. Due to the rapid increase in heavy-duty transport, the global road network is showing visible signs of ageing in many places. In order to ensure that the road infrastructure remains func onal over the long term, older roads need to be rehabilitated. Wirtgen has developed the high-performance W 380 CRi cold recycler specifically to meet these requirements.

Comple ng structural road rehabilita on more quickly Road rehabilita on projects all have to meet the same requirements, regardless of where they are being carried out. They must be cost-eﬀec ve, eco-friendly, and above all, finished quickly - because me is of the essence. Patchwork repairs are neither sustainable nor do they address the root cause.

Wirtgen cold recycling technology The cold recycling process which, at a minimum, recycles the surface and base course material, is already popular today, and demand for this solu on will con nue to

grow in the future. In the in-place cold recycling process, for example, the asphalt surface is removed either in full or in layers, depending on the level of damage, by a recycling train opera ng across the en re width of the pavement in a single pass, mixed with binding agents on site, and then the pavement is paved again immediately.

The W 380 CRi At the heart of this recycling train are tracked cold recyclers such as the new W 380 CRi from Wirtgen. With available working widths of 3,200 mm, 3,500 mm and 3,800 mm, the recycler mills the road between 100 mm and 300 mm deep in most applica ons. At the same me, it granulates the material and transforms it into a new, homogeneous material mixture by adding binding agents such as cement, bitumen emulsion, or foamed bitumen. With a mixing capacity of up to 800 t/h, the cold recycler can feed enormous quan es of recycled material to a Vögele paver via its swivel-mounted and height-adjustable discharge conveyor at the rear. This makes it possible to complete long stretches of road in a single day of work. Final compac on is carried out by Hamm tandem and tyre rollers.

The Wirtgen Group oﬀers product solu ons that cover the en re in-place cold recycling value chain, with a range of machines required for the process in its por olio - including the W 380 CRi cold recycler. 36

THE SINGAPORE ENGINEER July 2019

RAILWAY & ROAD ENGINEERING

Wirtgen’s tracked recyclers use the down-cut process when recycling. The company developed this process, in which the milling and mixing rotors rotate in sync, years ago. This method has become an essen al part of day-to-day recycling opera ons, as it makes it possible to selec vely vary the par cle size of the material being processed - especially in the case of fragile, thin, old asphalt roads.

Durable foamed bitumen mixture Roads rehabilitated using the cold recycling process also have to meet the same durability requirements as roads designed and built using conven onal methods. With the development of its own laboratory equipment, Wirtgen has created solu ons which guarantee that the rehabilita on measures will be cost-eﬀec ve and sustainable even before they are carried out. As a result, the recycler not only makes it possible to define the ideal composion of the RAP (reclaimed asphalt pavement), but also to directly analyse its quality and proper es using samples in triaxial and spli ng tensile strength tests. The quality of the foamed bitumen can also be precisely defined in the materials laboratory before star ng the rehabilita on project. Cold recycling, par cularly with foamed bitumen, is becoming increasingly popular with road authori es and construc on companies. In this process, the foamed bitumen is processed in-place with the exis ng building material. The newly produced bituminous mix is known as BSM (bitumen-stabilised material). A er final compac on, it shows long-term and high load-bearing capacity. Viewed from a long-term perspec ve, BSM has another advantage. The foamed bitumen mixed in leads to selec ve adhesion within the cold recycling layer and thus prevents cracking. The permanent layers prepared in this way form the ideal founda on for the final asphalt layer with considerably reduced thickness.

reduced fuel consump on and lower CO2 emissions. Most importantly, the cold recycling design makes it possible to reduce the use of binders by up to 50% - the area with the greatest poten al savings, since binders are s ll the biggest cost factor in road rehabilita on. Thanks to the special proper es of BSM, cold recycling technology results in low costs over the en re life of the roads. Since the RAP is immediately recycled and the associated logis cs are lean, in-place cold recycling enables projects to be completed much quicker than with conven onal rehabilita on methods. The en re series of machines required for the rehabilitaon process can fit in the width of just one lane. On twolane roads, this means the recycling process is carried out across the width of a single lane, while traﬃc can be routed along the other side of the roadway, past the construc on site in one lane. Outside normal working hours, the en re road width is usually available, as the freshly recycled pavement can also be used immediately a er compac on has been completed.

Wirtgen cold recyclers can also be used as eﬃcient, high-performance, large milling machines employing the up-cut process.

Cost-eﬀec ve design with low life-cycle costs Another advantage of the cold recycling process that cannot be understated is the significant poten al for energy savings during material processing. The raw materials do not have to be dried or heated, which means that 10 litres to 12 litres of fuel can be saved per ton, compared to conven onal rehabilita on methods. By almost completely reusing the surface course, the need to transport building materials can be reduced by up to 90%. At the same me, companies can cut resource consump on by 90% and completely eliminate the need to dispose of materials. This results in significantly

The W 380 CRi is characterised by its ease of opera on, with new automa c func ons, main control panels that can be posi oned as required, and an on-board diagnos c system. THE SINGAPORE ENGINEER July 2019

PROJECT APPLICATION

INSTALLING HEAVY AND FRAGILE WALL PANELS

ON A CONGESTED PROJECT SITE The work was part of a government rail upgrade programme in Australia. Australian rental company Metcalf Crane Services utilised the integrated heavy-duty jib, (known locally as a ‘machinery runner’), on a Grove GMK5250L from Manitowoc, to handle the delicate unloading and installation of wall panels for a new rail corridor project in Seaford, Victoria. Using the machinery runner from the Grove all-terrain crane, which is integrated into the crane’s swingaway jib, allows the use of both main and auxiliary hoists for the operation of two hooks simultaneously. The design of the machinery runner provides greater distance between the two hooks, making it ideal for applications such as panel installations. The crane served a vital function on the project, as the wall panels, which weighed up to 30.5 t, had to be rotated from their horizontal position on the delivery vehicle to a vertical position for installation. Ideally, this operation had to be completed by a single crane as the congested job site meant finding space for a second crane to assist was a challenge. Adding to the complexity of the project was the delicate design of the precast deflection panels, which required all rigging equipment for the installation to be

installed vertically to avoid imposing any potentially damaging side loads on the panels. To ensure this part ran smoothly, Metcalf Crane Services used its own modular spreader bars, designed and manufactured in-house by the company. The installation of the eight precast deflection wall panels is part of the Seaford Road grade separation project, being managed under the Victorian state government’s AUD 6.9 billion Level Crossing Removal project. The project aims to remove 50 of Melbourne’s most dangerous and congested level crossings by 2022. Work on the Seaford Road section of the project is being managed by a consortium of Lendlease Group, Acciona and WSP Global. The GMK5250L has a maximum capacity of 250 t, a main boom length of 70 m and a maximum tip height of 110 m. It is one of the most powerful and versatile five-axle cranes on the market, with one of the highest-rated capacities and the quickest set-up times in its class. In Australia, the crane remains one of the best-selling five-axle machines, with over 20 either working or on their way to the country.

The integrated heavy-duty jib, (known locally as a ‘machinery runner’), was u lised on a Grove GMK5250L to handle the delicate unloading and installa on of wall panels for a new rail corridor project in Australia. 38

THE SINGAPORE ENGINEER July 2019

PROJECT APPLICATION

FORMWORK SOLUTIONS FOR THE MADISON TOWER IN LONDON Challenges, in terms of space constraints, produc vity and safety, were successfully overcome in the construc on of the 182 m-high residen al building. High-rise buildings are an icon of modern society. Not many high-rise projects are iden cal and the same can o en be said for the concrete structure and therefore the formwork solu on for crea ng the structure. Measuring 182 m high, The Madison Tower located adjacent to Canary Wharf in London is currently se ng its mark as one of the tallest buildings in the UK. The 55-storey building will deliver 423 new homes, including over 100 aﬀordable homes, in addi on to an extensive new public garden, a residents’ lounge, and business facili es, and residents can also enjoy superb views of the River Thames. When completed, the tower will fea ure a facade that produces a ripple-like eﬀect, and will also house a private club facility for residents, a state-of-the-art gym, swimming pool and spa. The development also benefits from excep onal transport connec ons which are to improve further with the soon-to-be completed Crossrail Sta on at Canary Wharf. This will provide a direct link to the city, West End and Heathrow Airport, helping Canary Wharf live up to its reputa on as one of Europe’s fastest growing business districts.

At the core For the concrete core of the building, which measures over 34 m in width, AJ Morrisroe, who was responsible for the construc on work, specified that the construc on process use Doka’s self-climbing Pla orm SCP. Constrained by a ght footprint, AJ Morrisroe required a solu on which allowed access for the steel fixing opera on, and the proposed system enabled mul ple processes, such as steel fixing, prefabrica on, and formwork placement, to run concurrently to help speed construc on on-site. Doka’s technical team incorporated the hydraulic self-climbing SCP system into the original proposals due to the requirement for a climbing system which could climb independent of the crane as this resource was to be highly u lised on site for other li ing ac vi es. One common challenge on high-rise construc on projects is the high wind speeds. This was true in the construc on of The Madison. Doka’s self-climbing Pla orm SCP ensured high levels of safety, not only because of the capability to raise the system in higher wind speeds than tradi onal crane opera ons permit, but also due to the system providing a fully enclosed workspace which shielded the core construc on process from external weather condi ons. Another added benefit is that the system prevents fall-hazard loca ons opening up during 40

THE SINGAPORE ENGINEER July 2019

For the construc on of the concrete core of the building, AJ Morrisroe specified the use of Doka’s self-climbing Pla orm SCP.

reposi oning as the en re pla orm is raised hydraulically in one li process. The versa le system also has integrated access in terms of pla orms and stair towers which provide addi onal safety during working opera ons and for up-and-down access. In combina on with the SCP climbing system, Framax Xlife was the systemised wall formwork panel system used to form the building core concrete. In total, over 500 m² were used on each pour of the core, due to its proven track record in terms of fast forming mes, a clean concrete finish and comprehensive workplace safety processes. With access to the building a key considera on throughout the construc on of the tower, Framax coupled with SCP allowed full access to perimeters of the building, whilst being securely connected to the structure at all mes.

Next genera on beamless slab formwork For the construc on of the building’s concrete floor slabs, AJ Morrisroe opted for Doka’s systemised panel system, Dokadek 30, for all typical floor layouts which were from Level 2 up to Level 53. Having previously used the system on the Nile Street project, in the London borough of Hackney, AJ Morrisroe had the confidence needed to confirm this was also the right systemised slab solu on to use at The Madison project. Dokadek 30 not only provides up to 3 m² of handset slab formwork in one panel, but also allows for easy-to-follow installa on processes from the floor level below and simplifies site logis cs due to the small number of components required. High wind loads on site also meant a slab formwork system that would withstand these condi ons was compulsory - a challenge easily met by

PROJECT APPLICATION

Dokadek, with prop heads having a built-in an -li guard to prevent panels from being li ed. The project used over 700 m² of Dokadek, as panels were cycled up the floors as construc on progressed and lower floors could be struck. The design also required the incorpora on of specially constructed made-to-measure panels for par cular bespoke architectural requirements in the slab construc on. U lising both standard panel sizes (2.44 m x 1.22 m and 2.44 m x 0.81 m), AJ Morrisroe reported simpler logis cs, in addi on to improved inventory control for site management. In addi on, by using the same system on the whole project, AJ Morrisroe was able to reduce me needed for many diﬀerent training and awareness crea on requirements, which is an added benefit in today’s market where skills shortages are a major concern for contractors. One major benefit of the Dokadek 30 solu on is the reduc on in working at height, due to the capability of the system to be installed by working from the floor level below, and clear set up and dismantle processes. Lee Henry, AJ Morrisroe’s Project Engineer said, “Doka went above and beyond our expecta ons by supplying technical exper se for some bespoke panels we re-

quired, which were specially tailored for the project, to provide an eﬃcient solu on for all in-situ areas on the more complex geometry on the slab edges, as required by the architect”. “The Dokadek system provides a great process for installing from below and mi gates the requirement for our teams to be oﬀ the floor un l the final carpentry infill areas are undertaken. But even here, the integrated beam hangar solu on means that it is really only necessary to be on the top deck level just to fit the final plywood panels themselves around columns or other final infill areas”, he added.

Project challenges One major challenge on the project was the significant geometry changes to the core of the build, however, using Doka’s self-climbing Pla orm SCP, the team was able to specifically design a solu on to adapt to changes in the core walls. The first small change was on Level 17 where some of the walls were removed. With the adaptability of the system, no changes were necessary. As previously men oned, another challenge imposed was the limited site storage and working space, coupled with there being no possibility for prefabricated reinforce-

Doka’s systemised slab panel system, Dokadek 30, with bespoke sec ons for The Madison. THE SINGAPORE ENGINEER July 2019

PROJECT APPLICATION

ment and limited crane use. Doka’s Pla orm SCP was used to overcome these par cular challenges. Measuring in at 195 m² on pla orm +1, the SCP system gave the addi onal benefit of enabling the top working pla orms to become an assembly and storage area capable of bearing the load of equipment weighing up to 40 t in a working situa on and 20 t during climbing opera on. The system itself also requires fewer anchors to the building, which means cost and labour savings for customers.

technical support are provided swi ly and professionally. An enterprise forming part of the Umdasch Group, Doka employs a worldwide workforce of 7,000.

Improving efficiency From planning and implementa on, through to comple on, Doka provided ongoing technical exper se, in addi on to regular account management support and site visits to help deliver AJ Morrisroe’s vision for The Madison Tower. This involved detailed drawings, including sta c calcula ons, which ins lled confidence that the individual formwork units were suitable for the intended use on the project. AJ Morrisroe took advantage of Doka’s experienced Formwork Demonstrator to deliver on-site product support as well as toolbox talks to site personnel on how to use the formwork systems effecvely and safely. This, in turn, resulted in greater levels of produc vity on-site. Doka’s Senior Sales Manager, Stuart McClagish said, “We are really pleased to be able to offer our customers addi onal services such as the on-site demonstra on as it really helps ensure the products are being used most effec vely and as safely as possible, in real-life-situa ons”.

Ahead of schedule

PROJECT CREDITS Project The Madison Tower Loca on London, United Kingdom

Doka’s digital concrete maturity monitoring sensor, Concremote, was specified for its ability to op mise concrete pour cycle mes, mi gate safety risks and help be er plan labour and equipment requirements. The award-winning Concremote is a non-destruc ve solu on which uses temperature and me to calculate compressive strength gain in concrete, in real- me.

Type of structure High-rise Residen al / Oﬃce / Retail

Already ahead of schedule, AJ Morrisroe was able to achieve a 6-day cycle (originally the schedule planned for a 7-day cycle me) with the help of the Concremote solu on. All in all, 4,980 m³ of concrete were poured for the 179.23 m-high service core. Concremote enabled the team to understand the compressive strength of the maturing concrete more eﬀec vely and as a result, it was possible to shorten the cycle me for construc on of the building core by a considerable margin. In total, a savings of 30 construc on days was achieved. The data was collected by the Concremote sensors which were incorporated into the core, wall, and slab formwork solu ons to help AJ Morrisroe decide on the op mum moment for stripping the formwork.

Main Contractor Balfour Bea y Construc on

Doka Doka is a world leader in developing, manufacturing and distribu ng formwork technology for use in all fields of the construc on sector. With more than 160 sales and logis cs facili es in over 70 countries, Doka has a distribu on network which ensures that equipment and 42

Concremote determines the op mum me for post-tensioning opera ons or stripping the formwork.

THE SINGAPORE ENGINEER July 2019

Height 182 m Developer LBS Proper es

Construc on work AJ Morrisroe Architect Make Architects Start of construc on 08/2017 End of construc on 07/2019 Doka systems used Self-climbing Pla orm SCP Framax Xlife Dokadek 30 Concremote

All images by Doka

CONSTRUCTION MANAGEMENT

USING BIM FOR CONSTRUCTION QA/QC by B K Chew, Product Marke ng Associate Manager, FARO Technologies It is simpler than imagined. The construc on industry’s lukewarm recep on towards technology is a challenge that is well-documented, and one that has held the market back from its full poten al, over the last couple of decades. According to KPMG’s ‘Global Construc on Survey: Building a technology advantage’ (September 2016), where over 200 major project owners and contractors rated themselves on technology adop on, only 8% of these companies emerged as ‘cu ng-edge visionaries’. While this minority group adeptly made use of various solu ons such as project management informa on systems (PMIS), automated digital workflows, data and analy cs, and Building Informa on Modeling (BIM), most others have remained conserva ve, choosing to rely on ‘tested and proven’ methods of project management. O en, companies cite a lack of certainty in reaping the full benefits of new technology, vis-à-vis the costs and risks involved. For some others, it is the mere reluctance of stepping out of one’s comfort zone that hinders innova on.

DIGITISATION AND BIM IMPLEMENTATION That said, market observers believe that a new day is dawning for the industry, as companies increasingly recognise the posi ve impact that digital technology has on the full life cycle of a building, beyond its construc on stage. Government bodies around the world have begun promo ng and manda ng the use of BIM (Geospa al World, ‘BIM adop on and implementa on around the world: Ini a ves by major na ons’, 5 April 2017), in the hope of transforming industry prac ce, improving produc vity levels, as well as boos ng integra on and collabora on across the construc on value chain. In essence, BIM is a digital representa on of the physical and func onal characteris cs of a project, which forms a reliable basis for decisions during the project’s life cycle right from the conceptual stage, through preliminary and detailed design phases, to construc on and as-built (or maintenance and occupancy management) stages. This

The concept of Traceable Construc on The transparency and traceability of a construc on project oﬀer great benefit to all project par cipants in terms of me and money. These factors are also essen al for successful lean projects. Today, project owners have access to eﬃcient, forward-looking solu ons that address a diverse range of needs in the various life phases of a building - whether it be design, build, or operate. These solu ons will enable the following func ons to be carried out: • High-speed data acquisi on, on-site registra on, and survey control (On-site Capture). • Planning and designing of building projects based on as-built condi ons (As-built Model & Design). • Speeding up of workflow by projec ng virtual templates for prefabrica on or at construc on sites (Design Layout). • Performance of immediate, real- me build and verify analysis throughout the en re project (Quality Control). • Communica on of data across a building’s life phases (Data Connect & Share).

An overview of traceability across the construc on value chain.

THE SINGAPORE ENGINEER July 2019

CONSTRUCTION MANAGEMENT

informa on can be shared with various project member groups on demand, providing greater transparency and traceability across stages. But perhaps most a rac ve of all, BIM implementa on oﬀers project owners tangible benefits such as shorter project melines, less material wastage, and increased profitability.

AN EASIER APPROACH TO QA/QC IN CONSTRUCTION Responding to the industry’s need for a simpler and be er way to harness the capabili es of BIM, so ware developers today oﬀer construc on professionals the ability to con nuously monitor a project with real- me comparisons against CAD designs. Project owners and contractors can now confidently manage all quality assurance and quality control processes on a single platform, throughout a building’s life cycle.

Valida on of construc on to design specifica ons The ability to ensure buildings and structures are constructed exactly to design specifica ons is of paramount importance to architecture, engineering and construcon (AEC) professionals. By comparing 3D scan data with design models at each stage, project owners can detect incorrect placements or missing features (for example, walls, columns, beams, pipes) before it is too late. This reduces prolonged hours of manual valida on to mere minutes, making construc on QA/AC analysis a breeze.

Tolerance evalua on Keeping projects on schedule and minimising any wastage within a project are also high priori es for AEC professionals. While cost and schedule overruns are the

norm in the construc on sector, companies should not be resigned to accep ng them. Today, it is possible to perform accurate measurements quickly and easily on key elements of a project, as frequently as is necessary. Contractors can rou nely inspect construc on work for adherence to building standards, whether for floor flatness, beam cambre, or wall plumbness (ver cality). In the grand scheme of things, these measurement tasks can help accelerate project schedules and reduce expensive scrap and rework.

Posi oning and monitoring Beyond performing quality checks on building structures, project owners will find BIM useful for liability documenta on, risk mi ga on, and quality prefabrica on. Comprehensive so ware solu ons are now even equipped to verify shi s and movements, displaying changes over me with 4D analysis. AEC professionals can monitor adjacent buildings during construc on and evaluate any site deforma on (they can measure movement or se ling over me). Addi onally, companies can project design templates for prefabricated parts and assemblies with the help of a laser projector, or posi on structural elements and prefabricated parts in real- me using laser trackers or total sta ons.

FARO BUILDIT CONSTRUCTION SOFTWARE The FARO BuildIT Construc on So ware is a pla orm that seamlessly integrates the func ons described above. The so ware enables users of laser scanners to perform immediate, real- me build, and verify analysis throughout an en re project, facilita ng a new level of cost management and opera onal eﬃciency.

Each stage of the construc on can be validated by comparing the 3D scans of the construc on with the digital design files. 44

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CONSTRUCTION MANAGEMENT

ACQUIRING A NEW IMAGE

FARO

Slowly but surely, the construc on industry will make headway in shedding its image as one of the least digised sectors. As various members of the AEC profession open up to technology adop on, equipment and so ware providers will oﬀer even more solu ons to meet the industry’s needs, so that what seems impossible today may quickly become tomorrow’s reality.

Headquartered in the US, and with its Asia Pacific regional headquarters in Singapore, FARO is a trusted source for 3D measurement, imaging and realisa on technology. The company develops and markets computer-aided measurement and imaging devices and so ware for several ver cal markets including Factory Metrology, Construc on BIM, Public Safety Forensics, Product Design, and 3D Machine Vision.

Full digital evalua on can be performed, of tolerances for any project feature such as floor flatness.

With 4D monitoring, scans can be compared over me, to capture structural changes such as shi or dri . THE SINGAPORE ENGINEER July 2019

IES EAB ATTENDS IEAM 2019 The International Engineering Alliance Meeting (IEAM) is an annual meeting that provides a platform for discussions on international benchmarks for engineering education and expected competence for engineering practice. This year’s edi on of IEAM was hosted by the Hong Kong Ins tu on of Engineers (HKIE) and held at Crowne Plaza Hong Kong Kowloon East from 9 to 14 June 2019. It was a ended by over 200 delegates from across the world, including IEA members from 37 jurisdic ons within 28 countries and regions.

The IES Engineering Accredita on Board (EAB) delega on was represented by Er. Ho Siong Hin, Dr Lim Khiang Wee, Dr Lock Kai Sang, Er. Ong See Ho, Er. Tan Seng Chuan, Er. Raymond Tay and Dr Toh Siew Lok. In his opening address, Dr David Holger, Chairman of IEA Governing Group (GG) gave an update on the GG projects over the past one year and led a discussion on the possible restructuring of the IEA’s system of governance, which included proposals such as crea ng an IEA Assembly, expanding the defini on of IEA Aﬃliate Organiza ons, and establishing IEA as a legal en ty.

IEAM 2019 was held at Crowne Plaza Hong Kong Kowloon East from 9 to 14 June 2019. Photo: The Hong Kong Ins tu on of Engineers

Er. Tan engages in discussion with fellow engineers during the mee ng. Photo: The Hong Kong Ins tu on of Engineers

THE SINGAPORE ENGINEER July 2019

IES UPDATE

Of interest to IES EAB were the talks by Prof Elizabeth Taylor [then-Deputy Chairperson of the Washington Accord (WA)] on “Processes and Procedures for Con nuous Review of Signatories”, and Dr Holger on “Refining the Accord Review Process”, in which they proposed ways to refine the WA accredita on process. These changes will be further deliberated upon at IEAM 2020 in Cape Town. In recogni on of their progress in engineering educa on, Myanmar, Indonesia and Thailand were admi ed as provisional signatories to the Washington Accord during the WA Closed Mee ng. Furthermore, the jurisdic ons of Chinese Taipei, Korea and New Zealand were granted a further six years of full signatory status, a er passing their scheduled reviews. It was also heartening to note that Engineering Council United Kingdom (ECUK), the engineering body represen ng the UK, has accorded equal privileges to graduates from WA-compliant programmes of other signatories, enabling them to register and prac ce as engineers there. The last item on the agenda for the Closed Mee ng was to elect a new Deputy Chair of the Washington Accord. Out of the three candidates who stood for elec on, Dr Lock was voted in for the posi on. At the Asia Pacific Economic Coopera on (APEC) Agreement Closed Mee ng, Er. Tan (who was also the mee ng’s chair) reported on the progress of the APEC

Project to promote connec vity of professional qualified engineers in this region. Two recommenda ons were made, the first being to incorporate the work of APEC Mutual Recogni on Agreements for engineers into the APEC Services Compe veness Roadmap (ASCR) and encouraging the governments of member economies to engage the private sector regarding the APEC Engineer Register. The second recommenda on was to harmonise the Register with the professional engineering services prac ces of individual member economies and to encourage greater par cipa on with the Register. IES EAB also par cipated in the Interna onal Professional Engineers Agreement (IPEA) Closed Mee ng, chaired by Dato Ir. Dr Gue See Sew and co-chaired by Mr Jerry Carter. IPEA is a mul -na onal agreement between engineering organisa ons in the member jurisdic ons, on which a framework for the establishment of an interna onal standard of competence for professional engineering is built. Each member organisa on is then empowered under this framework to establish a sec on of the Interna onal Professional Engineers Register. On the whole, IEAM 2019 was very well organised, with robust discussions at a regional and global level on the advancement of engineering standards, as well as ample opportuni es for networking and catching up with fellow engineers from across the world.

Dr Lock pitches his candidature for WA Deputy Chair to the assembled delegates. Photo: The Hong Kong Ins tu on of Engineers

THE SINGAPORE ENGINEER July 2019

IES UPDATE

PEs SHARE THEIR EXPERIENCES WITH NTU ENGINEERING STUDENTS An engineering talk was held on the sidelines of the NTU Engineering Fest 2019 that took place in late March. Four Professional Engineers from diﬀerent disciplines were invited to speak to students about their experiences and career journeys so far. The honest sharing of their perspec ves enabled to students to view life as an engineer through a more realis c lens, and helped them to understand some of the possible challenges that they too would face when they enter the workforce. The PEs also enlightened their a en ve audience on the many possible opportuni es that they could pursue upon gradua on, and spoke to many of them face-to-face over dinner at the end of the talk. The IES-NTU Student Chapter would like to extend their gra tude to Ers. Ahmad Nadim Bin Zainal, Nancy Chan, Mohamed Aboobucker Muhammad Aman and Gary Gay for making me to come down to the campus to share their valuable experience with the budding engineers.

(From le ) Er. Mohamed Aboobucker Muhammad Aman, Er. Ahmad Nadim bin Zainal, Er. Gary Gay Yun Lin and Er. Nancy Chan Hui Ching pose for a group photo with the NTU Student Chapter exco.

For the NTU engineering students, it was a frui ul evening spent understanding the career journey of a professional engineer.

ADVERTISERS’ INDEX

Building and Construc on Authority ––––––––––– Page 11

IES Membership ––––––––––––––––––– Inside Back Cover

Cementaid (S.E.A.) Pte Ltd –––––––––––––––––––– Page 05

Mul Nine Corpora on Pte Ltd –––––– Outside Back Cover

Delta Energy Systems –––––––––––––––––– Page 08 & 09 (Singapore) Pte Ltd

Singapore University of –––––––––––– Inside Front Cover Social Sciences

IES 53rd Annual Dinner –––––––––––––––––––––– Page 39

World Engineers Summit 2019 –––––––––––––– Page 01

THE SINGAPORE ENGINEER July 2019