INNOVATION AND COMMUNITY PARTICIPATION BUILD THE BEST ROUTES

Within the global context, South Africa’s road network ranks in the top 10 in terms of size, and in parts is widely regarded as being of world-class standard, particularly along the national routes managed by Sanral. However, in general, there’s a growing maintenance backlog – well illustrated by the National Department of Transport’s Vala Zonke pothole repair programme. Managed by Sanral, it aims to stem the deterioration of secondary and rural roads at provincial and municipal level. Funding support comes from various sources, a key one being the Provincial Road Maintenance Grant (PRMG).

“It’s a fact with asset management that if you don’t catch it at the right time, then the remedial cost increases exponentially. So, the first priority is to routinely maintain our existing roads, keep asset registers up to date, and ensure that the right materials and technologies are employed, both from sustainability and durability perspectives,” explains Kevin Govender, technical executive: Transportation at Naidu.

Asphalt trends

In this respect, Naidu closely follows international asphalt trends to investigate what works best in practice for the South African environment. Tried and tested products include high-modulus asphalt (EME), which has been proven globally over the past 30 years or so for its performance under extreme traffic loading. “That’s an increasing factor in South Africa given the major shift from freight rail to truck haulage along our main commercial routes,” says Govender.

Another tried and tested technique is the employment of crumb rubber binders in asphalt to improve fatigue and durability performance. Since the rubber is sourced by recycling used tyres, there’s an added environmental benefit from a circular economy perspective.

“Rubber bitumen has not been prominent locally in recent years. However, it’s beginning to resurface, with plans in the pipeline to incorporate it as part of bitumen rubber asphalt on current Sanral upgrades,” Govender continues.

“The bitumen rubber will be part of the opengraded design, which will have the added advantage of excellent surface drainage to prevent the risk of aquaplaning across four to five lane carriageways, as well as the added benefit of noise dissipation, meeting the SANS threshold specification of 55 decibels.”

Labour-intensive construction

While the construction of flexible asphalt pavements is traditionally highly mechanised, there is increasing scope for elements of labourintensive construction (LIC). Examples include pothole repair programmes, in addition to general maintenance, plus the construction of low-volume roads.

Naidu is a pioneer in LIC practices and has received industry recognition that includes a National SAICE 2018 Award for project D1613. The latter also received a Commended Award at the 2018 KZN Premier’s Service Excellence Awards.

Completed for the KZN Department of Transport, the scope entailed the upgrading of a district road, using a combination of LIC and plant-based construction techniques. However, over 36 000 m³ of material was moved by hand. A key element of Naidu’s out-of-the-box design was the employment of geocells that were filled with batched concrete to form a functional low-volume road.

All of Naidu’s geometric designers have completed the firm’s CETA-accredited NQF 7 course on LIC, which is also offered to the industry, along with an NQF 5 programme aimed at contractors and construction monitoring.

“We understand the need to create jobs at the ‘coal face’ of the roads industry, which starts with optimising LIC at the design stage,” Govender explains.

Projects in progress

Naidu currently undertakes design and construction monitoring responsibilities for a range of clients nationally.

The firm’s flagship project is the N3 Ashburton to Murray Road upgrade (Package K), where construction commenced in March 2023. The works contract value is approximately R2.4 billion and involves widening the existing two-lane freeway to four or five lanes in each direction over a distance of approximately 5 km. The construction programme is scheduled to run over four years.

The influence of technology

In today’s environment, how projects are designed and executed is increasingly influenced by advances in digitalisation. The Covid-19 years – with their enforced remote way of working –accelerated its adoption, particularly in the field of building information modelling (BIM) as defined by ISO 19650.

“We decided that the timing was right to move with the rest of the world to BIM and to motivate the advantages of BIM over a road project’s life cycle to the clients we work with. One of our projects at the time was the realignment of Section 27 on the N2 at the Umhlali and Umvoti river bridges. We thought this would be an ideal opportunity to run a BIM pilot study, with the Umvoti southbound carriage section selected for this purpose. This was supported by Sanral,” Govender continues.

The Umvoti southbound section was converted into a 3D model in order to create a digital twin, importing all the relevant engineering and quality control data into a BIM cloud repository. “It was a great learning curve for us, the client and the contractor to see the elements come together in near real time, and to be able to interrogate the process within a common data environment.”

3D migration

Naidu’s design engineers have now all made the shift from 2D to 3D software, with Philani Mkhize, the then senior technologist and now regional manager: Gauteng, spearheading the shift to 3D design across Naidu’s Roads & Highways Design Unit. Philani was also part of the BIM pilot team on the Umvoti project.

“One of the key benefits of BIM is multiple stakeholder collaboration to design, cost, construct and maintain infrastructure assets over their lifespan via a virtual hub. From my experience, the speed and ease of project delivery are vastly improved. It’s also amazing to see the BIM model develop as a live rendition of what is happening on the construction site via successive reporting updates,” Mkhize explains.

Excelling in bridge design

When it comes to connecting economies and communities, bridges are one of the essential elements in transportation design, for both road and rail. This is a core part of the integrated offering provided by Naidu and headed up by Josh Padayachee, technical executive: Bridges & Buildings. A key focus is on ensuing that structures are functional and climate-change resilient.

“Most clients in South Africa have adopted Sanral’s drainage manual, but there’s an unprecedented frequency of severe flood events that requires industry to collectively revisit future implications. Sometimes it’s a non-engineered response, like ensuring the eradication of

ROADS & BRIDGES

alien vegetation, which reduces the hydraulic capacity of rivers and especially bridge openings,” says Padayachee.

In KwaZulu-Natal – which experienced some of the worst floods in South Africa’s history during April 2022 – infrastructure repair work is ongoing. One of Naidu’s projects in the design phase is the Illovo River Bridge for clients Prasa and Transnet. During the floods, the approach embankments were washed away, compromising the integrity of the steel truss bridge, which is more than 70 years old and past its design life. Options being proposed by Naidu include a new incrementally launched bridge across the estuary aimed at minimising any environmental impact.

On the N2 Umshali Bridge, a similar scenario was experienced, where debris had dislodged the bridge deck. Naidu is currently implementing a solution that entails jacking the bridge horizontally and then vertically back into place. This ensures that the existing bridge does not have to be demolished.

Bridge inspections with apps

“Road asset management is important, but it’s crucial for bridges,” Padayachee continues, adding that Naidu recently won a tender via competitive bid to inspect all of eThekwini Municipality’s approximately 400 bridge structures. “We’re also inspecting bridges in the region for Sanral and the KZN Department of Transport in the wake of the 2022 floods.”

Allied to this, Naidu has developed an in-house app for bridge inspections, aligned with TMH 19, which greatly speeds up data capturing and analysis. The same is true for the firm’s other purpose-designed apps for fibre routing, health and safety, pavement management systems, and water-loss management.

The bridge app generates a high-level budget on estimated repair costs, with structures listed in terms of their maintenance priority according to a condition index assessment. Asset owners can then plan accordingly. These inspections must be completed by a Colto-accredited bridge inspector, with any immediate health and safety concerns identified and alerted to the client.

Rural connections

“An area we’re particularly proud of is our rural bridge programme, because these are so significant in changing the lives of communities previously cut off by raging river crossings from reaching schools, markets, jobs, health facilities and entrepreneurial activities,” says Padayachee.

“Another aspect is that many of the contractors involved are emerging SMMEs without extensive experience in bridge construction. It’s a great opportunity for us to make our contribution to boosting empowerment and capacitation through alternative design approaches. On top of this, our staff on-site go way beyond supervising the project: we provide practical training in areas like fixing steel reinforcement, setting out shutters and the process required for concrete placement,” he continues.

A classic example of a successful project is the Tugela River Bridge, measuring 210 m in length. This was intentionally designed as a modular composite structure to facilitate its on-site installation in a relatively remote rural setting.

The construction programme was undertaken by a historically disadvantaged contractor together with 11 emerging contractors. The project won a National SAICE Award for Technical Excellence and a Highly Commended Award in the Community Based Category. At the SAICE KwaZulu-Natal Branch Awards, it also won the Community Based Award and the Technical Excellence Award.

It was one of the first projects in the history of South Africa to show that a project could be very technical, while still enabling community participation and varying contractor skills levels. Naidu’s design minimised the risk to the contractor because there was no need for scaffolding in the river. The 40 m truss spans were lifted into place by crane and topped with a concrete deck.

Value-engineered for society

“Transportation and social infrastructure projects in general are vital elements of South Africa’s economic reconstruction and recovery initiatives. And wherever possible, we need to enable employment and build capabilities. In this respect, it’s clear that both high- and low-tech design and construct techniques can deliver great results. Plus, they can all come together within the BIM domain,” Padayachee concludes.