Helsinki Central (EN)

Helsinki Central M+M² - MOBILITYHUB & MARKET SQUARE

Bauhaus University Weimar Department of Architecture Study Programme: archineering MASTER THESIS Helsinki Central M+M² - Mobilityhub & Market Square

by Felix Pascal Küster Summer Term 2012 Prof. Dr.-Ing. Jürgen Ruth Suppl. Prof. Dr.-Ing. Reinhard König Dipl. Ing. Sven Schneider

Helsinki Central M+M² - MOBILITYHUB & MARKET SQUARE

Abstract 07 Analysis History in brief 13 A climatic classification 19 Transportation systems 21 Töölönlahti-Area 23 Library competition 27 Space Syntax Analysis (global) 31 Design 10 central statements 37 Urban interventions 39 Conception 41 Programme 43 Space Syntax Analysis (local) 47 Blueprints 49 Atmospheric perspectives 55 Further Elaboration Structural planning 61 Zollinger construction method 65 Static assumptions 67 Cost effectiveness and sequence 71 Annex Bibliography 73 Photo credits 73

Helsinki Central - Mobilityhub & Market Square

Abstract

From a Central Library to a Mobility Hub First thoughts about the competition programme Initially, the idea to build a new central library in the heart of the capital seemed challenging and promising at the same time. The international architectural competition is a part of the World Design Capital Helsinki 2012 programme. The spot on which the new library should be located is situated in a triangle between the main station, the Finnish Parliament House and the Museum of Contemporary Art. Also it is within walking distance from the pedestrian zone and shopping streets. The area is defined by public buildings that are scattered like pavilions within the vast green space that connects suburbia to the inner city. The probably best known of these buildings is the Finlandia Hall, which was designed by Alvar Alto in 1971. There is a high public awareness for this specific park as the city is elsewise surrounded by water. In wintertime it is commonly used for ice-skating or for cross-country skiing. During the summer it is an important recreational zone for the city and as such hosts a vast variety of events. Even the countries’ biggest festival for music and art takes place there.

After an intense research on site and having all evidence taken into account I came to the conclusion that something far different to a library was most needed to improve this specific spot of town. The cities’ landscape of libraries is highly developed and well accepted by the local population. One impressive historical library building is situated in the very centre of old town. It is constructed in a neo-classical style and dates to the mid nineteenth century. Within short range a large new university library is just about to open in 2012. In Pasila, which is an important transportation hub in the north of the city, a large library has been built in 1986. This library can be most easily reached by all commuters.

Figure groundplan of Helsinki; Scale 1:20,000

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Helsinki Central - Mobilityhub & Market Square

HEALTH & SUSTAINABILITY

urban gardening & organic food

emission free building

wellness & fitness & SPA

local materials

increasingly complex environment

emission reduction

preservation of urban relaxion areas

spatial complexity vs. orientation

making use of technology

holistic approach

new materials

intelligent logistics

security & automatisation

new energy sources

different needs

INTERCONNECTIVITY COMMUNICATION TECHNOLOGIES GLOBALISATION VIRTUALITY ABSTRACT SCIENCE

SMART TECH

INFORMATION CYBERSPACE AMBIENT INTELLIGENCE

HOME

LIBRARY

TECHNOLOGY CONVERGENCE

KNOWLEDGE-BASED ECONOMY

60k 50k 40k 30k 20k 10k

knowledge based economy knowledge intensive ind.

edu

other industry high tech industry 99 04

94

Source: Tekes

cooperation with industries

convergence & emergence

parallel & segregated

overlaps & unforeseen encounters

education facilities

CULTURE

diversing lifestyles CHANGING PROFESSIONAL LIFE sleep work leisure 00 DAY

08

16

01 WEEK

24

00 DAY

07

01 WEEK

08

16

24 24/7 07

traditional working hours

future worklife balance

life expectancy 90 80 70 60 50 40 30 2025 1975 2000 Finland World

population by age group 5 mio > 65 years 4 mio 3 mio 15-65 years 2 mio 1 mio < 15 years 1975 2000 2025

book lending machine

hybrid environment

opening hours

age related intrest changes

adaption to impairments

DEMOGRAPHIC CHANGE

Source: EarthTrends

Source: EarthTrends

CONSUMPTION PATTERNS

ABC

mass-production

custom made books

user defined contents

SCALE MATTERS

+

local vs. global

global connectivity

individualism & local integration

LIFE SCIENCE public

industry

increasing knowledge ethnic implications

conservation of the species seed bank

uncontrolled traffic-growth

regulation through accessibility

MOBILITY

Possible operational concept for a future library?

First reflections about the given design task

education

researchers

1211121121 2222212112 2212121121 11111211121 1111211211 = 11121112112 1211212112 2212121121 11111222211 1212111211

controlled access to genetic databases

foster creativity

Abstract

Besides, there is a dense network of decentralized district libraries in place, which has an important role in public life. So there arises the question, whether there would be a real need for a new central library. Would it be worth to risk giving up the well-functioning existing infrastructure, in favour for simply having a new spot that would mainly serve representational purposes?

As a central location and as gateway to the capital, the area surrounding the main station, in which the construction site is located, has a high potential to improve its spatial qualities. At the moment, the station forms a barrier between the historical heart and the political and cultural centre of the capital. The building which is constructed in the Art Nouveau style is flanked by a highused street and city-bus terminal on either side. The pedestrian accessibility towards the old town is made difficult by dense traffic and an appropriate visual connection to the government district is still leaking. Unfortunately a good orientation for new arrivals is difficult as well. Additionally the bigger part of all regional trains can only be accessed from outside the station hall as the two wings of the building only allowed an extension on the buildings north side.

All these parameters taken into account I was able to rethink the whole task on a broader scale. Finally it led to a design proposal which reflects the perceived opportunities for improvements on different levels and which puts a fully new complexion to the whole site.

The new design combines the different traffic streams in a more optimized way, while decreasing their harmful impacts such as congestion, noise and pollution. In addition a new connection between the two currently separated districts alongside the railway compound is made. In terms of urban planning the government building is given the counterpart it needed in order to fit in with the cultural establishments that are agglomerated in the TÜÜlÜnlahti area.

Finally this design proposal revives a specific feature of Helsinki: During the early twentieth century, there was a need to connect the harbour to the railway network. As the inner city already had a dense structure at the time, an orbital bypass following the coastline was found as an appropriate solution. Since the line had long been disused, there now is a chance to establish a new bicycle path without junctions. The new mobilityhub would function as the final link, that would then close the circular structure of this new public bicycle and foot path.

In the following, I am going to describe the current situation on an urban scale as well as the different detailed analyses on a building level which finally led to this unexpected proposal.

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Helsinki in Figures

Total Area

Total Landmass

km²

km²

Water

km²

Population

Density

2012

population per km²

Helsinki Central - Mobilityhub & Market Square

View on the Senaatintori Church, with the Senate Square in the foreground and the National Library in the background, both designed by Carl Ludvig Engel (above).

City Port Katajanokan-Kanava (left-hand).

Töölönlahti-Area with the Music-Hall, the Museum of Contemporary Art and the House of Representatives (middle).

Main Station, designed by Eliel Saarinen in 1919 (right-hand).

History in brief

Helsinki - Helsinfors

The â&#x20AC;&#x161;White City of the Northâ&#x20AC;&#x2DC;

At the mouth of the river In the sixteenth century Finland was part of Sweden. In 1550, King Gustav Vasa founded the city of Helsinki in an attempt to control and regulate the trade taking place between the local Finnish farmers and the merchants of the flourishing town of Reval (nowadays Tallinn) across the Baltic Sea. The land around the mouth of the river Vantaa was donated by the crown and inhabitants from other villages in southern Finland were compelled to move in order to populate the new port town.

However, by 1640 there was a need to find a better site for the harbour and the town was moved to a new location closer to the open sea. This meant that the old town fell into decline, and today very little remains of the original wooden settlement at the mouth of the river are found. Archaeologists have established that there were no more than 500 inhabitants in the original Helsinki.

Built on rock The new location was to be the rocky peninsula nowadays called Kruununhaka. The town plan clearly reflected the clarity and systematic ideals of the Renaissance.

It can be assumed that the Swedish surveyor Anders Tortenson was the planner of the modest town of timber dwellings where two-storey houses were a rarity. By 1700, the town had a population of just over 1,000.

However, the army of the Russian Tsar, Peter the Great, began to invade along the length of the coast from St. Petersburg all the way to Stockholm and as a result, in 1713 Helsinki was completely destroyed.

The fortress in the Gulf of Finland Although Sweden made peace with Russia, SwedenFinland lost furthermore territory to Russia during the second half of the eighteenth century. In a result, the Sveaborg fortress was built to defend the Gulf of Finland. At that time it was the largest public construction project in the Kingdom of Sweden.

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Helsinki Central - Mobilityhub & Market Square

The 1817 town plan by Johan Albrekt Ehrenstrรถm. The buildings, which are marked in red are designed in neo-classical style by Carl Ludvig Engel and serve representational purposes.

Historical citymap and drawings of public buildings from 1841

History in brief

Built on islands just south of the city, with heavy fortifications of granite and houses of brick, the fortress was to be the first urban environment in the entire province of Finland. The coastal fort was of major social, economic and architectural importance to Helsinki, which was now beginning to grow again and soon reached a population of 4,000.

The ‚White City of the North‘ During the early part of the nineteenth century, Sweden was again at war with the tsar and when the fortress of Sveaborg capitulated in 1808, the province of Finland fell to Russia. The tsar decided that it should become an autonomous Grand Duchy, with a dependent government and army but an own fiscal system. The previous provincial capital had been situated in Turku, but under the new regime and because of its strategically neutral position, the capital was now moved to Helsinki in 1812.

In 1810 the wooden city was again destroyed by fire, providing an opportunity to plan from scratch. The construction was financed from St. Petersburg by Tsar Alexander I.. The city layout was proposed by Johan Albrekt Ehrenström and the main buildings were designed in a neo classical style by an architect from Berlin, Carl Ludvig Engel (1778-1840). These classical buildings

with their light-coloured stucco façades created the impression of a Hellenic city. Later it was described as the ‘White City of the North’. In 1850, the freshly built city housed a population of around 15,000.

The era of industrialisation From 1860 until the Second World War, the city’s population increased in average by four per cent p.a., a similar rate to other centres in Europe. As a result of the rapid industrial growth, the city began to take on new appearance, with neo-classical structures giving way to brick buildings of up to fife storeys. The railway system was developing rapidly, thus promoting the growth of wooden working class neighbourhoods around the main centres of industry.

At the beginning of the twentieth century, there was a strong nationalist movement in Finland. Within the cultural sphere it was led by the artists Jean Sibelius, Akseli Gallen-Kallela and Eliel Saarinen. After the Russian Revolution in 1917, Finland was granted independence

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Helsinki Central - Mobilityhub & Market Square

Citymap from 1909.

The railroad is now leading directly into the city centre.

Also visible is the new ring connection to the harbour which bypasses the inner city.

Master plan for the Helsinki metropolitan region of 2002.

History in brief

and a new state was born. In 1918, Saarinen produced a master plan for Greater Helsinki. In his vision of a capital city he symbolised an independent nation’s faith in the future. At the beginning of the Second World War, Helsinki had a population of about 250,000.

After the war, Finland’s need to recover and the obligation to make reparations to the Soviet Union resulted in even further industrialisation, with the ship building industry gaining an immense importance to the city and Nation. At the same time an intense period of urban expansion began, in which the creation of many suburban areas allowed a doubling in population until 1970.

The post-industrial period

The 2002 Helsinki Master Plan

By 1960, the industry’s role as driving force behind the urban development was losing importance. Public services, administration and education were now the bases for development. The 1970 master plan paved the way for post-industrial times. District centres such as Itäkeskus and Malmi were planned. Then in 1972, the district of Paslia was built to relieve the tightly congested city centre and to act as a secondary centre. Regional and local railway networks were taking shape and the use of private cars increased substantially. The population had reached an amount of 50,000 by then.

Since the nineteen-seventies, the Helsinki Master Plan, which is an interdisciplinary planning tool covers the full metropolitan region and organises traffic as well as land use. In recent years, a new master plan is drawn up at intervals of about ten years. Still, town planning is a continuous process which follows the changes in society.

The most recent plan of 2002 predicts a population of about 600,000 for 2020. It describes the city as loose agglomeration of high density areas and includes reservation zones for parks and public spaces. The plan generally foresees future residential zones for blocks of flats or low-rise single-housing. High-rise zones are only planned at Jätkäsaari, Sörnäistenranta and Hermanninranta. Another important aim is to balance the amount newly built business premises in relation to the housing development.

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Helsinki Central - Mobilityhub & Market Square

The diagram illustrates the monthly mean temperatures in degree Celsius and the preciperation levels for Helsinki in millimetres

This comparison chart illustrates the yearly mean temperature distribution and preciperation levels in Finland

500

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F

M

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Months

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Temperature [째C]

Preciperation [mm]

Helsinki, Finland

A climatic classification

A Climatic Classification

Constructing in boreal climate zones

Lying approximately between latitudes 60° and 70° north, Finland is one of the world‘s northernmost countries. Of all world capitals, only Reykjavik is situated farther North than Helsinki. The city has a boreal humid continental climate.

Owing to the mitigating influence of the Baltic Sea and Gulf Stream, temperatures in winter are much higher than the far northern location might suggest, with an average in January and February around −5 °C. Temperatures below −20 °C occur normally a week or two per year. However, because of the latitude, days last less than six hours around the winter solstice and the sun follows a path, close to the horizon. The very cloudy weather at this time of year further accentuates the darkness. Conversely, Helsinki enjoys long days in summer, close to nineteen hours around the summer solstice. During the summer, there are noticeably fewer hot days than in the interior parts of the country, and temperatures exceeding +30 °C are rare. Helsinki’s average temperature around the entire year lays at +6.7 °C.

The rainiest season in Helsinki is generally the fall, when the average monthly rain volumes vary between 5579 mm. The year’s rainiest month is August. The driest season is the spring, when the average rainfall volumes remain at 30-40mm.

The effect of windiness on the climate of Helsinki and the competition area is considerable. Southwestern winds prevail in Helsinki. Temperature fluctuations between the sea and mainland affect the area’s airflows and consequently trigger winds. Because Helsinki is surrounded on the east, south and southwest by large water areas, the winds from these directions reaching the city are occasionally strong. At the yearly level, winds coming from the south and southwest prevail in Helsinki.

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Helsinki Central - Mobilityhub & Market Square

View across the mainstations forecourt and the highly frequented Brunnsgatan road: With the new City-Tunnel, a huge portion of the current through traffic could be diverted. This would strongly enhance the connection to the pedestrian zone and allow a revitalisation of the square.

Transportation systems

Transportation Systems in Helsinki

Getting from A to B in the metropolitan region

Public Transportation All public transportation in the Helsinki metropolitan area is managed by Helsinki Region Transport, which is the regional transportation authority. The diverse public transport systems consist of trams, commuter rail, the subway, bus lines and two ferry lines. The Helsinki Metro, opened in the year 1982, is the only rapid transit system in Finland. It has stations roughly every 250 meters and several Park and Ride lots connected to it.

In 2006, the construction of the long debated extension of the system west into Espoo was approved, and an eastern extension into Sipoo is considered for the future. The possibility of a Helsinki to Tallinn Tunnel is also being researched. The rail tunnel would connect Helsinki to the Estonian capital Tallinn and further linking Finland to the rest of continental Europe.

Bicycles Helsinki has an over 1,000 kilometre long bicycle path network that is also used intensively by pedestrians.

Approximately half of the cycle paths are paved with asphalt. Cycling paths are for the most part two-way.

Helsinki also has an extensive network of recreational paths, approximately 70 km of which run along the shoreline. A specific potential has the former railway bypass that has a near circular structure. Partly on the shoreline, partly without junctions on a sublevel, it nearly surrounds the inner city, ending at both sides of the main station.

Road-Traffic

Aviation

The backbone of Helsinki‘s motorway network consists of three semi-circular ring roads, which connect expressways heading to other parts of Finland. Ring I-III connect to the western and eastern arteries of Länsiväylä and Itäväylä respectively. The prospective Keskusta Tunnel will bypass the inner city from east to west and pass right beneath the site. The intention for which it is built, is to take the pressure from Brunnsgatan. This street which passes in front of the train station could be closed for through-traffic in due course.

Air traffic is handled primarily from the international Helsinki Airport, located approximately 19 kilometres north of Helsinki‘s downtown area, in the neighbouring city of Vantaa. Originally built for the 1952 Summer Olympics in Helsinki, the airport served fifteen million passengers in 2011 and it is the fourth largest airport in the Nordic countries. Helsinki‘s second airport, Malmi Airport, is mainly used for general and private aviation. Helicopter flights to Tallinn are available from Hernesaari Heliport.

Sea transport The Port of Helsinki is owned by the city of Helsinki and is Finland‘s main port, specialized in unitized cargo services for Finnish companies engaged in foreign trade.

The value of the cargo traffic at the Port of Helsinki represents approximately one third of the value of the entire Finnish foreign trade and two-fifths of the Finnish foreign trade transported by sea. Helsinki is also the busiest passenger port in Finland, with diverse services to Tallinn, Stockholm, Travemünde, Rostock, Gdynia and St. Petersburg.

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Helsinki Central - Mobilityhub & Market Square

Aerial view on the inner city (left) Birds perspective on the Töölönlahti Area seen from north-east (right above) Birds perspective on the Töölönlahti Area seen from south-west (right bottom)

Töölönlahti-Area

The Urban Development of the Töölönlahti Area

A central park in the heart of the capital

The redevelopment of the intermediate zone between the main station and the Töölönlahti (‚lahti‘ = lake) is in full progress. The Töölönlahti bay is flanked by the Tölöö district in the west and half separated from the see by the railroad dam in the east. It is further framed by the Mannerheimintie road and the main station. North and south of the bay, the city’s largest green belt connects the northern suburbs to the historical heart of the capital.

The area which is currently in redevelopment lay idle for decades, after it was no longer used for the railroad.

Meanwhile it became an important part of the green park area, mentioned before. Still several important buildings are scattered like pavilions along the edges of that zone. From an urban point of view the buildings are all standing quite separate from each other, each defined by a unique design vocabulary. Therefore, they are also rather functioning like islands in the vast green space. The flanking street is built on an elevated level at about five meters above the park level. The important Finish Parliament House, called the Eduskuntatalo faces to that street, its prominence being highlighted by a further elevated position.

There had been several master plans for the area in place, the latest trying to form a dense urban district out of it. Among many difficulties that are faced by the planners, it appears unlikely, that they will be able to bridge the vast distances between the buildings in order to form urban squares by edging the intermediate spaces. Additionally, the area is positioning itself in an increasing concurrence to the current pedestrian zone.

The inner cities large shopping spaces would inevitably loose value after the redevelopment.

One important aspect that is specific to this green space, leading from the outskirts right into the core city is often overseen. As the city is built on a peninsula that is surrounded by the sea, there are natural limitations for growth. Therefore the urban density has increased over the centuries and today there are few open public spaces left. The real potential for the area south of the Töölö bay lays in its protection from further development. It should be seen as a part of the highly valuable central park instead of a city development zone!

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Helsinki Central - Mobilityhub & Market Square

Municipality

Opera

Central InďŹ rmary Historic Wooden Mansions

Finlandia Hall Botanic Garden

University

National Museum Music Hall Parliament Building Museum for Contemporary Art Main Post / Museum

Main Station University Library Dome Church

Museum of Finnish Culture

Ateneumin Museum

private owned building public owned building commercial bulding

Nutzers

Töölönlahti-Area Helsinki Central Railway Station is a widely recognised landmark in central Helsinki and the focal point of public transport in the Greater Helsinki area. The station is used by approximately 200,000 passengers per day, making it Finland‘s most-visited building.

The original architectural competition received 21 entries, and was won by Eliel Saarinen, with a pure national romanticist design.

This design sparked off a vigorous debate about the architecture of major public buildings, with demands for a modern, rational style. Saarinen himself abandoned romanticism altogether and re-designed the station completely. The new design was finished in 1909 and the station was opened in 1919.

The Parliament House, seat of the Parliament of Finland sits on Arkadianmäki hill facing the Mannerheimintie road. It was designed

by Johan Sigfrid Sirén in 1931 and features an architectural style combining Neoclassicism with early twentieth century modernism.

The exterior is red Kalvola granite.

The façade is lined by fourteen columns with Corinthian capitals.

Notable later additions to the building are the library annex completed in 1978 and a separate office block, completed in 2004.

The glazed rectangular cube on the south-end of the Töölönlahti area was designed by Jan Söderlund and Antti-Matti Siikala in 1999. It houses MP-Offices as well as the office of Finland’s biggest daily newspaper and a large diagonal public mall, which connects the south-east corner to the north east corner. The mall is often used as a shortcut between the main station and the Music Hall. Especially in winter time, these connecting malls and arcades, which can be found all across the city are well preferred alternatives to the cold and windy streets.

The Helsinki Music Centre, which was finished in 2011, is now home to Sibelius Academy and two symphony orchestras, the Finnish Radio Symphony Orchestra and the Helsinki Philharmonic Orchestra. Before its construction, a two-part architectural competition on the design was held in 1999 and 2000 and won by the Turku-based LPR Architects.

Chief architect Marko Kivistö has stated that the forms of the outside are deliberately simple, leaving the building to reveal a more varied and dramatic interior. The green color of the copper façade is designed to connect the building with the surrounding park. The architects worked with the acoustics consultant Yasuhisa Toyota and so far received uniform praise by the two symphony orchestras.

The Finlandia Hall, a concert hall with a congress wing, was designed by Alvar Aalto. The work began in 1967 and was completed in 1971. The main features of the building‘s exterior are the great horizontal mass of the building proper and the towering auditorium that rises above it. The main external material is Carrara marble. The marble continues in the interior, and is supplemented by hardwood, and ceramic. The well-known iconic building has however been criticized for severe design errors and since the new concert hall is in place, it is now mainly used as a congress center.

The Kiasma Museum of Contemporary Art alludes to the basic conceptual idea of its architect, Steven Holl. The construction of the rather controversial building started in 1996 and it was opened in 1998. Today, the museum exhibits the contemporary art collection of Finland. The gross floor area is about 12,000 m², of which the exhibition spaces account for 9,200 m².

The water motif, which is a central element in the exterior design, begins at the foot of the statue of Marshal Mannerheim and runs along the building in a black granite pass which ends at the northern corner of the building. Carl Gustaf Emil Mannerheim was a military commander during the Finnish Civil War of 1918 and later during the Second World War.

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Helsinki Central - Mobilityhub & Market Square

LOGISTICS

20 m² distribution substation

400 m² service and loading area

SERVICE SP AC

200 m² library collection storage

60 m² refuse store

80 m² returns automat

200 m² library materials handling

COL LEC TIO N

500 m² lounges

60 m² IT and equipment

SP A CE

EVENT SPACES

80 m² cleaning facilities

50 m² building management and server room

140 m² fixed client service points 300 m² quiet areas

40 m² building maintenance store

ES

S ISTIC LOG

600 m² childrens' world

150 m² furniture and stage prop storage 1600 m² library collections area

200 m² living lab 350 m² multipurpose hall

LEAR NING A ND DO 100 m² ING digital fab lab 100 m² music- / video-recording-studio 60 m² tv- / radio-studio

230 m² games room

240 m² interactive spaces

400 m² client office area

40 m² local storage points 120 m² library exhibition space

40 m² backstage

150 m² client workrooms

180 m² rentable exhibition space

BY 440 m² meeting and lounge area

250 m² public toilets

office (staff)

30 m² toilets (staff) 50 m² changing and wash-rooms (staff)

170 m² public services

100 m² bookstore (ext.)

240 m² public sauna

EX TE

160 m² lobby functions

VIDERS

30 m² performance-stage

OR

50 m² lounge (staff)

RNAL SERVICE P RO

100 m² pop-up info spots

SPAC ES F

STAFF FACILIT IES 300 m²

MAIN L OB

490 m² cinema

400 m² group work + meeting spaces

300 m² restaurant

200 m² café

The various interactions between the different spaces are illustrated via a graphic organization chart. The chart transmits the complex room programme into a readable structure. Unintended redundancies and disproportionate scales become visible.

Library competition

Architectural Competition for a new Central Library A hybrid room programme for a prominent location My thesis’ design task was at first strongly oriented on the international architectural competition that was called out during the World Design Capital Helsinki year.

Sought was a proposal for a new central library for the City of Helsinki.

An excerpt from the competition programme The need for a new library in the centre of Helsinki became topical already in the 1990s in connection with the development of the Kamppi-Töölönlahti area. The need for a Central Library is based on the one hand on the strategic principles of developing the wellbeing of the citizens, urban fabric and competitiveness, and on the other hand on the changes that have taken place within the field of library operations.

The new Central Library supports the objectives set out in the city’s strategy programme. It enforces learning, skills, personal cultivation and culture as a basis for welfare and competitiveness. Additionally it enforces user centred innovative environments and services together with enterprises and users using the participatory product development model, the so-called ‚Living Lab‘ operational model. The Central Library adds to and diversifies the vitality of the Helsinki city centre and also enlivens and diversifies the new urban environment created in the Töölönlahti area.

The new Central Library will be much more than a traditional library. It will be a dynamic entity comprised of the physical spaces themselves as well as technology, library collections, staff, cooperation partners and clients. Also the library will be at the forefront of the renewal of the city’s library services and the ‚Heart of the Metropolis: the Heart of Helsinki‘.

Specific preconditions for the design task In this context it is important to be aware of the fact that the recent competition is the third in line, all three sharing similar goals and purposes. These planning processes led into vivid discussions but didn’t result into feasible solutions nonetheless. One important outcome of this pretext is a successively complex competition programme being tidied up into all and every secondary room. But many unintended redundancies and disproportionate scales became visible once the programme had been analysed and visualized. The main purpose of the library has been literary pushed aside through the many other functions. The library collection space and the needed storage area together account for less than a fifth of the complete 10,000 m² room programme. Altogether the programme degrades the actual library-part of the building to about the size of an average district library, but at multiple costs.

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Helsinki Central - Mobilityhub & Market Square

A well-functioning and dense network of district libraries stretches across the whole city and metropolitan region. Those decentralized small libraries are completed by the National Library as well as by the newly built University Library.

The installation of a new Central Library in the city centre would certainly cause redundancies, budget cuts and maybe even closures for the existing system.

Accordingly, a balanced decision between the following is to be made: Is there a need for another â&#x20AC;&#x161;bigâ&#x20AC;&#x2DC; library that would serve mainly representational purposes or is the cultural value of the existing network worth being protected and strengthened?

Library competition

Opinions on the Library System in Helsinki

Central Library vs. District Libraries

When analysing the structure and proceedings of libraries in Finland several questions about the intentions behind the ‘Central Library’ project arise. One important finding is, that the new building wouldn’t host the National Library’s archives but rather be an enlarged version of a city library. With the city library network in distinct to the National Library or the several university libraries being currently spread in a decentralised network across the city.

The historical National Library is located on Senatoori Square, right opposite of the Dome Church. The library, which was designed by Carl Ludvig Engel first opened in 1845. Beside its function as host for the national archive it is an important historical example of architecture. The highly impressive premises are nowadays operated by the university library network. Within walking distance, the new main facility of the university library has opened in 2012. Furthermore, there is another remarkable historical library, the Rikhardinkatu library, which was designed by Carl Theodor Höijer in 1881. One large public library opened in 1986 in Pasila. The district, which is located five kilometres north of the main station was originally designed to serve as a ‘second city centre‘. The large transportation hub which was installed at the time now guarantees easy access for all commuters.

Beside these larger libraries, there is a dense network of district libraries in place. Those serve as highly valued magnets for the local society and conserve a culture which is specific for Finland. Typologically, these district libraries can be seen as hybrids combining a library as an archive and reading place with a cultural centre. As such, they do serve various additional functions. From a café and meeting place to a bookstore, exhibition or even an event space, the full range of cultural life is covered.

To unlock all potential of this existing infrastructure the cross-linkage could be intensified. One comprehensive information system could open access to the full content of all the different archives in place. In combination with all digital resources there could be a virtual de-central library installed. Right on every citizen’s doorstep, people could have equal access to all the information they need. All this could be achieved through the well accepted existing interfaces - the district libraries.

This scenario somehow contradicts the idea of a ‘Central Library in the heart of the metropolis’. For the architectural competition again, a hybrid in a wider sense and on a different scale becomes subject. The library there should become an integrated cultural centre for the whole city including reading and learning areas, interactive features, exhibition and presentation spaces, a cinema as well as shops and a recording studio. The building should be multifunctional, urban, prestigious, interactive and so forth.

One starts to wonder who the actual target client for such a building could be. Local users would need to accept now longer journeys and experts as well as researchers would probably miss an appropriate working climate in such an entertaining environment. Finally, for tourists and visitors who are in fact the most targeted audience the building would be just another point on their agenda. And then again, the running and maintenance costs would probably cast doubt on the further existence of all additional district libraries. But aren‘t these characteristic examples of Finnish culture finally worth to be kept and protected?

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CHOICE

INTEGRATION

CONNECTIVITY

Helsinki Central - Mobilityhub & Market Square

Space Syntax Analysis of the given situation

Space Syntax Analysis (global)

Space Syntax Analysis of the Urban Context

Comparison of different building positions within the existing setup

The Space Syntax Analysis is a tool that looks into spatial configurations on different scales ranging from single floor plans to a full city scape. The method was originally developed by Bill Hiller, Julienne Hanson and their colleagues at the Barlett University College in London during the early nineteen eighties.

The analysis method contends a set of tools, some of which better applicable on smaller scales, others allowing a look at more global configurations. The most basic and directly interpretable tools are Connectivity, Integration and Choice. Those can be calculated via the Axial Line Analysis or else via the Visibility Graph Analysis. Connectivity is a local measure and represents the number of elements, which are connected to a certain element. As this calculation only takes into account the direct neighbours of an element, a superposition of all results is done, in order to achieve a patterned representation of all visual field areas, here called Isovist Field. Integration instead is a global measure and represents the relations of all elements to a specific element. It shows how well integrated different areas are compared to each other. Heavy used junctions are likely to be found in the visual centres whereas visually segregated areas are likely to be neglected. Choice indicates how often an element is passed, when calculating the shortest paths between all different elements, called Through-Movement. Intelligibility correlates Connectivity and Integration. In a well intelligible environment the visually integrated zones are highly connected at the same time.

The Intelligibility (here of the current situation) is a measure for the correlation between Connectivity and Integration

One huge constraint to the Space Syntax Analysis is that the choice of system boundaries can heavily influence the results. Another constraint lays in the fact that the method can currently only be applied in a plane.

This means that the influence of three dimensional topographies (e.g. to be able to look behind an obstacle) can’t be taken into account. To counter these problems, I made always two different calculations, one for all visible zones only and one for the actual accessible areas and superimposed the results of those. The same applies when streets cross junction-less on different levels. Generally it can be said that the mentioned methods work best for typical medieval old-towns, whereas it is most difficult to analyse zones in which different urban topologies (e.g. parks, pedestrian zones, roads etc.) interfere.

In the analysis of the Töölönlahti area different possible new layouts including the one, proposed by the 2003 Master Plan were compared with the existing situation.

One clear result is that in the existing situation the forecourt of the main station appears to be a bottleneck.

For pedestrians, as well as for car traffic there currently is no east- western cross connection north of it. Another finding is that all well integrated centres are to be found on the Mannerheimintie in distinct to the Töölönlahti area, which is comparably segregated. Also it is remarkable that the long visual axis guiding from the park, across the Tölöö bay towards the main station is only interfered by the VR Makasiini, a small abandoned building, formerly belonging to the rail company. The Choice measure confirms a main orientation in longitude. The intelligibility coefficient shows a remarkably low correlation rate of only 0.270878.

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CHOICE

INTEGRATION

CONNECTIVITY

Helsinki Central - Mobilityhub & Market Square

Space Syntax Analysis with the footprint that is forseen for the new library

Space Syntax Analysis of the area with a new building and a passage across the rails

Space Syntax Analysis (global)

In a next step, two further variations have been compared. Those specific ones are of high relevance as one shows the prospective layout according the current 2003 Master Plan and the other one tries to embed the outcomes of the analysis of the current situation.

The first variation according to the Master Plan foresees an additional building (the new Central Library) that takes up the building alignment parallel to the rails.

The visualised results show that the park and the main station are now clearly segregated from each other. The forecourt on the main station’s west front is weakened and now there is a hierarchy degrading the court and the passage to the backside. Meanwhile, the space between the office building and the Music Hall shows no signs of centralisation or integration.

This strongly contradicts the assumption of the urban planners who intended it to become a new urban square. The already strong orientation in longitude is further emphasised through the linear building shape.

And a proposed shopping mall, which is to be constructed in a gap just below the park level having an orientation from north to south would enhance this effect even further. The new square still wouldn’t be edged towards the north. And as a matter of fact, the measure of Intelligibility further decreases to a number of 0.179934 in that constellation.

The second variation leaves the site vacant but adds a new building and a passage, both bridging the rails. In this layout the visual connection between the square next to the main station and the park is kept. Furthermore, three heavily integrated centres emerge in the triangle between the Parliament Building, the Music Hall and the Main Station. Those are likely to be a result of the new passage across the rails and the new crosslinkage due to that intervention. The interception of the currently strong axis north to south by a new junction balances the system further.

Finally, the high potential of this layout is also probably most reflected by the results of the Choice analysis. The new connection is given about the same importance as to the nowadays often congested Brunnsgatan in front of the Main Station. Pressure could now be taken from that hotspot. This could have the same positive effect on cyclists and pedestrians as the new City Tunnel has on car traffic. The Intelligibility of this variation reaches with 0.434986 the highest value of three researched layouts. It can thus be assumed that it would also be the most advantageous for the Töölönlahti area from an urbanist point of view.

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The Local Climate in Figures

Mean Temperature

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Helsinki Central - Mobilityhub & Market Square

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A view across the project area with the main body spanning across the rails. The green area stretches towards the front of the main station (above).

All arriving traffic streams are combined above and beneath ground level.

10 central statements

10 Central Statements about the Design Task

1

Green Belt / Central Park protect the park as an important element ~ take measures in order to keep it free of further development ~ connect the green belt with the heart of town

2

Arriving in Helsinki put a new complexion on the Main Station ~ adjournment of the bus-terminus / traffic calming ~ allocate qualities of an urban square to the space in front of the station

3

Network of Cycle Paths / Cross-Connection transform the former circular rail bypass into a cycle- / footpath ~ complete the circuit by bridging the rails

4

District Library preserve unique Finnish culture ~ make use of the existing network of well accepted city libraries ~ further strengthen their interconnection and vitalise communication

5

Mobility-Hub connect the City Tunnel, the relocated bus hub, the Main Station, the metro station, the cycle path network and the underground parking garage in one location ~ offer new waiting areas

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Vitalisation of the Töölönlahti Area create multifunctional public space ~ add additional value to the large stairs by using them as terraces / stands during the festival season ~ attract commuters as clients for the market hall

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Increased Quality for Passengers restructure all traffic streams in the Main Station area ~ build weather protection for the platforms ~ offer short connection between platforms ~ build market hall and heated waiting area

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Tradition in Timber Technology offer welcoming gateway to the capital ~ create lightness, translucency and warmth ~ use wood as sustainable construction material

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Bridge Building use small square section of bearing parts based on composite construction ~ build with drift construction ~ uphold functionality of the main station while all construction works

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Built on Rock lay foundations on the bare bedrock ~ an unproblematic intersection with the City Tunnel is possible ~ horizontal forces resulting from the curved roof are clamped by the bedrock

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Helsinki Central - Mobilityhub & Market Square

Situation Plan 1:5000

Urban interventions

Argumentation for a Bridge-Building

Urban interventions and creation of shape

The urban structure in the area is difficult to read. There are no common elements in terms of layout or shape. The Space Syntax Analysis has underpinned that impression as well. Public buildings are scattered all across the large Central Park without an underlying structure or interaction between. The proposed new urban square would hardly be encased and therefore leak important qualities. The two large green areas and the adjoining districts on both sides of the railroad have no connection. The recently built bicycle trail abruptly ends in front of the station compound.

In regard to these weaknesses, there is one apparent solution imaginable. The rails could be crossed with a new building. Not only are the missing connections now made, but also the functionality of the Main Station could be notably improved. It would not only gain a so far missing weather protection for the platforms that serve the local trains, but it would also connect all platforms right in their centre. Heated waiting areas, close to the trains but inside the new building would further increase comfort. Small one and two storey high shopping cubes, being arranged in a loose grid around small squares and all laying within proximity to the waiting zones would create the atmosphere of a friendly market hall and guarantee high-value rental space for the contractor. A direct connection to an underground parking lot as well as to the relocated bus hub, both

linked to the prospective City Tunnel, would complete the picture of the new ‘Mobility Hub & Market Square’.

Finally, the now able to be closed circular cycle path would be completed with a guarded bicycle storage inside the building which would also help to encourage eco-friendly means of travel.

The Central Park could not only be protected from further development but find an increased connection towards the pedestrian zone. The Tölöö bay would be used as a design element and a lake and a basin would lead towards the Museum of Contemporary Art offering a lakeside promenade alongside the Music Hall and the Finlandia Hall. The footprint of the bridging building has a form of two funnels connected at their small end. It represents the alignments of the new cycle path crossing alongside the building and the one of the new City Tunnel that crosses beneath the building at the same time. The second direction emphasises the most direct orthogonal connection between the two districts.

The two main entrances on either side are emphasised by a set of impressive stairs that could serve as roofed terraces or stands during the festival season or just as welcoming gesture. The delicate rhomboidal structure of the roof opens up to the entrance sides in a same sense. The façades are kept lucent allowing the freestanding cubes to be seen from the outside. The peaks of the curved roof indicate the location of the market squares inside.

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Helsinki Central - Mobilityhub & Market Square

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Superposition of the bridge building, the traffic infrastructure and the shopping facilities

Conception

M2M² - Mall to Market-Hall & Mobility-Hub Interdependencies of traffic streams and added value The attractiveness of entrance situation to the city could be increased. An interconnecting link to different means of transportation had already been envisaged but not yet realised. The square in front of the main station is close to a gridlock and pedestrians preferably use the underpass to get into town. The bus terminus is divided into two sections on either side of the Main Station, most parts of it unroofed.

The prospective City Tunnel will soon connect to the underground parking lot next to the Main Station. But then again it hasn’t an appropriate entrance situation or interface. It simply leads through escape doors into the metro station. The new cycle path ends abruptly in front of the station compound.

With the design, Helsinki receives a new attractive and welcoming gateway. Not only symbolically it is naturally situated directly opposite the Parliament Building. The bus terminus is relocated, centralised and is directly connected to the Main Station. Part of the necessary traffic only takes place below the surface as the distant connections directly reach into the station via the new City Tunnel, whereas local buses are handled on the ground level. The so far neglected square in front and on either side of the main station is upgraded and becomes a pedestrian zone. The nowadays congested road can become a reduced-traffic area. The existing

underground parking lot with about 600 spaces receives an attractive entrance situation right inside the new Mobility-Hub. The currently projected City Mall would have several strong disadvantages. Not only would it be unprotected to the seasons, but especially its location in a gap below the sea level and its arrangement in a longitudinal direction from north to south would minimize the natural light that could directly reach the façades during the day. A barrier free access to the shopping entrances could neither be guaranteed due to the valley form. Then finally a Mall typologically wouldn’t fit at all in the middle of a green zone.

According to my design proposal this Mall would be relocated and replaced by a typologically far more attractive Market Hall. With thousands of daily commuters, supply and demand would easily meet, which would then result in an increased operating efficiency.

No further soil inside the valuable park area would be sealed for the construction and the new bridge would fulfil a number of synergetic purposes at the same time.

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Helsinki Central - Mobilityhub & Market Square

Always a good mix in the user structure: A possible new arrangement of the free standing cubes allows an adaption to changes.

Programme

Room Programme

Strolling about between alternating cubes

The building has a total of three levels above ground. All visitors from train commuters to cyclist enter the building on ground level. Below the cycle ramps and external stairs is the bicycle storage. Next to it stairs lead to the long-distance bus-terminal and the car park below or to the market hall above. The large external stairs, which guide to the park are dimensioned to function as terrace or stands during festival events. Their impression picks up and counter balances the large stairs in front of the Parliament Building.

Closed stairs or elevators guide from the rail platforms to the main floor on level 1. When arriving there, passengers can easily orient themselves along a main corridor on both sides of which the alternating cubes are arranged around courtyards. The gaps between the cubes which face the faรงade are built to serve as waiting areas, each allowing a visual connection to the correspondent platform. The rental spaces inside the cubes vary between thirty to three hundred square metres and between one and two storey versions. The Market Hall is divided into four zones that can be used in different ways. The central part serves as highly frequented connection-space and is faced by elevators and stairs.

This elegant promenade faces the Parliament Building on one side. On the other side the botanical gardens can be seen in front of the Broberg hill with the university facilities on its top. The second zone is formed by the waiting areas, mentioned before. Those are located in the quietest spaces and are visually oriented to the outside. A third zone is formed by the external passage-

ways that are divided-up between cycle traffic along the northern faรงade and pedestrians on the southern front.

These can be independently used from shop-hours or the operating hours of the train station. The fourth and final zone is defined by the courts around which the cubes are arranged according to different subjects (e.g. food-court, event-space or an informative area with tourist information and ticket-shop).

The delicate roof structure that stretches across the whole hall is made of glue-laminated timber beams that are arranged in a rhomboidal pattern. It is visible from every spot inside the building and the alternating height reflects the position of the courtyards beneath it.

The glass faรงade all around is set back in a way that allows the outer cubes to visually push through it. The roof itself aligns with the bridge edges and protects the external passageways. The transparency of the faรงade not only helps to maximise solar gains, especially during the winter months, but also visually underpins the freestanding character of the roof structure and the one of an entrance gate to the city.

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Helsinki Central - Mobilityhub & Market Square

Functional principles: (1) orientation and alignment (2) insert alternating cubes (3) guide view from the upper level (4) enlarge space to form courtyards (5) allocate waiting areas to the most segregated quiet zones

Programme

Main Characteristics of the M+M²

Visual connections and conceptual details

Elongated shape

Footprint resembling two funnels The long side is oriented towards the south Dynamic movement and pulling-effect Views towards north and south

Functional Cubes

Alignment alongside the connecting space Alignment around courtyards Ledges and setbacks Loose grid

The combination of the â&#x20AC;&#x2DC;Mobility Hubâ&#x20AC;&#x2122; that functions as subordinate structure with a market hall inside adds reciprocal value to the project. The amount of daily commuters that can be expected not only levers the amount of utilisation for community spaces (e.g. a district library) but is a calculable figure that increases the value of the rental spaces at the same time. 3,100 square metres of the totalling surface of 6,400 square metres are rental spaces. This relatively high proportion of rental spaces compared to the total built surface area helps to achieve the amortisation of the investment in a shorter period of time. Also the running costs are expected to be comparably smaller than in a comparable project of the same size.

Stepped heights

Variation between one and two storey cubes Guided views from the upper levels Roof follows the topography beneath

Exciting intermediate zone

Differentiated spaces between cubes Entrance zones for shops Communicative spaces, event spaces

Closed alcoves

Waiting areas Visual connection to the platforms Quiet zones

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A well-known specificity in Helsinki is its dense network of subterranean shopping arcades. The local climatic conditions impose a need for such well lighted and heated arcades. In this case, natural light gains can be maximised and a visual connection to the exterior is kept as well. The extension to the existing train station allows a restructuration of all travel movements. Distant train connections arrive in the historic part of the Main Station and reache directly into the heart of the city. The orientation for visitors can be improved. Local trains in distinct now halt below the Mobility Hub and thus changeover can be eased. Additionally to a linkage to the bus-hub and metro service car shares are now promoted being accessibly via the connected underground parking lot. Waiting times can be spent in the relaxing atmosphere of the Market Hall.

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CHOICE

INTEGRATION

CONNECTIVITY

Helsinki Central - Mobilityhub & Market Square

Space Syntax Analysis of the inner spatial arrangement

Space Syntax analysis (local)

A Space Syntax Analysis of the Building Interior

A detailed review of the spatial configuration inside the Mobility Hub

In order to assess the performance of the Mobility Hub, a Space Syntax Analysis reviews the spatial arrangement inside the Mobility Hub. The system boundaries encase the heated internal volume. The results of the Connectivity tool show, that the view field as well as its circumference is the highest in the middle section along the suggested corridor. Where the corridor passes the internal courtyards, peak values are reached. Visitors in these areas can easily orient themselves throughout the corridors and find the highest visual variety at these spots. A perspective is rich in variety when the view field in the spot is scattered the most. These spots are the ones that are most likely used when a person first scans a room that is new to him. Due to the bend at the middle of the building visitors firstly interact with the sphere directly in front of them, probably drawn to one of the courtyards, whilst as soon as they reach the midsection they can easily find their way through the building.

The peripheral parts alongside the length of the building host the waiting areas. Those are relatively quiet zones by definition, as they lay more segregated due to their spatial configuration. Atmosphere and usage fit well together. A visual connection through the faรงade onto the platforms is possible as well. The Integration tool confirms the high centrality of the central corridor. Focal points guide to the courtyards. The space additionally

opens in a vertical dimension in order to further encourage the effect of being visually drawn into the courtyards. These peaks in the roof structure allowto read the structure not only internally, but also from further away. In the central part of the building are two of the peripheral zones towards the outside, that are less segregated in comparison to their neighbouring elements.

Those are chosen for a set of secondary entrances to the building.

The Choice measure confirms the shortest paths along the corridor zone and through the primary and secondary exits. A fast change of trains as well as an easy orientation is comforted. In all other areas, a possibly high visual diversification was favoured, in order to increase the spatial qualities that correspond to a scattered Isovist Field. Every point within the market hall opens at least three possible ways around the cubes to reach a given other point within the hall. This feeling of being in a contorted market, in distinct to the one of being in a linear mall results in an increased resting time.

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Helsinki Central - Mobilityhub & Market Square

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Blueprints - Floorplans

Floorplans of the Mobility Hub Detailed subdivision and allocation of functions Market Hall (Level 1/2) 1 2 3 4 5 6 7 8

Main stairs and cycle ramp External foot and cycle path Main entrance Market hall Access to the rail-platforms One storey cube (rental space) Two storey cube (rental space) Waiting and lounge area

Mobility Hub (Level 0)

Bridge Level (see on next page)

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1 Goods and fire-fighting lift with connection

to loading dock in the basement 2 Passenger lifts 3 Luggage storage 4 Washrooms 5 District library 6 Floorplan variation (fashion shop) 7 Bicycle path 8 Foot path 9 Event space 10 Waiting and lounge area 11 Floorplan variation (hairdresser) 12 Informationdesk, ticket service 13 Floorplan variation (consumer goods) 14 Floorplan variation (footwear) 15 Floorplan variation (kiosk) 16 Floorplan variation (branch bank)

Bus terminus with 16 platforms Bicycle storage Main access to the bus terminal and the underground parking lot Storage for park maintenance Access to the rail-platforms Existing building MP office building Historical Main Station

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Helsinki Central - Mobilityhub & Market Square

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Helsinki Central - Mobilityhub & Market Square

Blueprints - Elevation plans

South and West-Elevation and detail of North-Elevation (right page)

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Helsinki Central - Mobilityhub & Market Square

Atmospheric perspectives

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View across the rails alongside the south front of the Mobility Hub with the Finnish Parliament in the background

Helsinki Central - Mobilityhub & Market Square

Atmospheric perspectives

57

Scene inside the Market Hall

Mobilityhub & Market Square in Figures

Rail-Platforms

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Helsinki Central - Mobilityhub & Market Square

Longitudinal Section

Structural planning

Main Elements of the Bearing Structure

Facts and figures The platforms are partly covered by the new bridge and there will be 6,400 square metres of heated area within the new building. Meanwhile, there will be 3,100 square metres of new rental space.

The vaulted ceiling improves the acoustic conditions and provides a good proportion of diffracting and absorbing elements. The inevitably highly-reflecting façades are tilted, which helps to avoid flutter echoes.

The bearing structure of the roof consists of two elements: The main bearing structure is formed by the girders that are arranged according to a ‘Zollinger’ grid and made of laminated timber. The battens above it function as secondary structure and through their shell form, a part of the load can be directly guided along the curvature.

Due to the geographical position of the building, natural lighting can be achieved best through the façades instead of the roof. The east-west orientation further helps in this context.

Span:

42.20 metres

Overstretched surface:

8,200 square metres

Height of the supports:

15.00 metres

Ridge height:

20.15 metres

Roof support grid: 33.10 metres (longitudinal direction) 32-42 metres (transverse direction) Bridge support grid: 16.50 metres (longitudinal direction) 11-21 metres (transverse direction) Materials: Timber > local renewable source; Steel > Know-How transfer from the ship builders can help to fit and weld the tube-knots properly

The various building functions can be deducted from the outer appearance of the cubes that are visually pushed through the façade. The glass façade has a maximum height of 11 metres on a length of 4 metres. Else, the height between the cubes and the roof ranges from 2.5 to 4.5 metres.

Bridge construction technique: Steel composite construction Bridge level:

6 metres

Overall length of the bridge:

255 metres

Emergency exits, which guide onto the platforms, are provided every 16.50 metres. Additionally, there are main entrances on all four sides of the building that guide directly into the exterior. The goods lift connects to a loading bay in the basement that can host up to 3 trucks at a time.

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Helsinki Central - Mobilityhub & Market Square

Functional principle of the roof structure: cover-battens with gaps, transversal battens, rafters, roof membrane, insulation layer, structural battens, girder grid

Structural planning

Technical Elaboration

Mayor structural components and the building envelope

The buildings structure can be subdivided into four different main elements. The first element consists of the roof shell, the roof structure as well as the outer rails and the V-supports. The second field of interest covers the bridge which supports on an independent construction. The freestanding shopping cubes, which are planned to easily adapt to changes in usage form the third element. Finally a fourth subject area covers the buildingâ&#x20AC;&#x2122;s envelope and energetic performance. A separate article further discusses the economic impact of the chosen techniques and also how those decisions further influence the sequence and speed of the construction.

additional insulation layer and increases the thermal resistance. So, as long as there is a sufficient snow cover, the air within the cavity will stay above freezing temperature. This also means that the formation of an ice layer below the snow can be avoided. Ice layers that would generally appear under similar conditions can in rare circumstances even result in structural failure and are certainly the main cause for snow-slips. Also the uneven surface, which is due to the small gaps between the battens helps to increase grip for the snow.

Roof shell The roof consists of the following layers, counted from the exterior: (1) cover-battens with gaps 40 x 60 millimetres; (2) Transversal battens 60 x 80 millimetres; (3) Rafters 80 x 160 millimetres; (4) Roof membrane: EPDM welding lanes; (5) Purlins / insulation layer 400 millimetres; (6) Structural batten-shell 60 x 80 millimetres; (7) Girder grid 20 x 800 millimetres, spacing: 3.3 - 4 metres.

The esthetical reason for the usage of an open timberbatten as external layer is to create a consistent impression and to limit the amount of different surface materials used.

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The second technical reason, for which the construction was chosen, is the battenâ&#x20AC;&#x2122;s shadowing effect.

The sealing membrane which is made of EPDM has a superior elasticity and it can easily adapt to the cyclic deformation of the roof. This deformation is due to load, humidity or temperature change. At the same time, the material has a poor UV-resistance and needs to be well shadowed. Although the timber is prone to weathering it is well ventilated at the same time. Therefore, the durability of external battens can even reach more than ten years. Replacement after that maintenance cycle can be done at economical costs.

But then, it serves as important technical feature at the same time. As the experience with similar constructions across Scandinavia had shown, there are two mayor physical advantages related to this type of roof cladding: The first advantage is due to the gap between the roof membrane and the batten itself. When snow covers the roof during the winter, the cavity serves as

The roof drainage is realised via the low points of the circular main girders. The water is then guided through the main supports into the sewer at the bottom. Due to the curvature of the roof, the main girders naturally provide a sufficient slope. Only the external batten shell cantilevers across those main girders. Due to its wind permeability it causes stall and a turbulent flow at its edges. This measure helps to lower the wind impact on the construction, which can become lighter in return.

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Helsinki Central - Mobilityhub & Market Square

V-Support: Technical Detail

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beam-axis The conventional Zollinger method has certain limits. detail "A" Because of the geometrical arrangement of the grid, bidirectional displacement each beam can only connect slightly shifted and twisted to its counterpart. Due to the described offset there is unavoidably a slight slip"A"that can add up on larger structures to notable deformations. To be now able to use the technique for spans, which are larger than some ten metres a solution had toa) be found. detail "B" b)

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shaped timber beams. Structurally the system canIV be defined as a mixture between a girder grid and an arched shell. Similar to all shell structures, the construca) b) x small. tions dead loadx is comparably to y y But in distinct ordinary shell structures, the roof form does not necestwisting... and lateral displacement sarily need to strictly follow the torque reference curve because it can also absorb a certain amount of bending force. system-axis

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Roof structure: Zollinger and beyond 1 The bearing structure for the roof is realised, based I on a technique that was already developed in 1904.

2 Mainly driven by economic reasons, Friedrich Zollinger II (1880-1945) researched on the possibilities to crea3 consumption. te lighter trusses with a lower material He came up with a solution that not onlyIIIsolved the 4 spans with the economic issue but allowed even wider typical intermediate supports being no longer needed.

IV Based on this simple but highly efficient construction method, the chosen approach differs from the majority x x which of recent parametric y designs y gain their aesthetical freedom at the expense of increasing costs and lower functionality.

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The conventional Zollinger method replaced the single detail "A" arched beam that would originally span the full distance at once by forming a rhomboidal grid of small equal detail "A"

In order to avoid harmful deformations a frictional connection that is able to lock all force is needed. If the opposing beams could be able to meet precisely in one knot a sheet metal could be slotted trough the intermediate beam. Screws would form ductile connections to the two arriving beams. The sheet metal then again would be bolted to the transversely running beam in order to hold it in an exact position. But how can the beams run into the right position?

The use of laminated timber in combination with a one detail "B" axis CNC milling machine will solve the issue of the lateral displacement. If the beams are further milled around detail "B"

Helsinki Central - Mobilityhub & Market Square

Perspective section in northsouth orientation

Static assumptions

Outer girders and V-supports a)

b)

The vertical curvature outer rails is Verdrehung... of the two circular und seitliche Verschiebung chosen in a same way as it was for the shell in general.

The rail adapts to the varying directionality and strength of the force which is transferred to the double pairs of Systemachse V-supports through it. Longitudinal to the building, the Stabachse V-form offers additional supports, reducing the maximum span, and bracing.

x

y

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The footprint of the building has a form, similar to two funnels, patched together on either small side. This has the global effect of bracing in the transversal direction, as is illustrated in the graphic at the bottom of the page. As the supports are fixed at their bases, the bracing is realised in longitudinal direction via frames and through the bridge bearings at both ends of the building. Vertically, the resulting forces from the arched roof are subdivided and the horizontal component is guided through the inclined pair of supports on either side of the building. Each double V-support accordingly "A" has two bases.

Randbogen

Randbogen

Detail "A"

Verschiebung

gegensinnige Verschiebungen

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Verschiebung

1 a second axis in addition, they will no longer appear I optically twisted. This measure would be taken for aesthe2 tical reasons mainly. Furthermore it would also help to II improve the connection to the batten shell on top of the 3 Zollinger grid by forming an even and plane support.

The cover batten helps to evenly distribute the III load but 4 also does it guide a part of the normal force, whereas the bending moment is absorbed by the girder grid. IV

"A"

Detail "B"

"B"

"B"

Hybrid Structure The proportion between the maximum rise and the span is 4.5 metres to 45 metres. This ten per cent proportion substantiates the assumption about the structure, being able to partly divert the load as normal force along the shell form. At the same time, the shell serves as bracing for the girder grid.

Instead of encasing the horizontal forces that arrive at the bottom trough a long and costly foundation, a connection to the bedrock is realised with rock anchors.

1 2 The granite rock on site lays partly bare or it is at a 3 maximum depth of about one metre beneath the1platDetail "B" 24 form level.

Detail "A"

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The curvature of the roof was created with the help of the membrane simulation programme Kangaroo. The software is a physics engine that is optimized for interactive simulation and form-finding.

1

2 3 4

Helsinki Central - Mobilityhub & Market Square

Longitudinal Section

Static assumptions

The mounting parts, which would be cast into the relatively small local foundation, would allow a fast and precise erection of the prefabricated supports. To increase the bond between concrete and mounting part, the reinforcement steel can be directly weaved through holes in the circular steel sheet. The gutter pipes are fed through openings in the part accordingly. Within regular maintenance intervals, they would be inspected via preinstalled service openings.

girder, the tensile force in the lower flange is accordingly higher, compared to the one in a bare laying steel girder. This is why the dimension of the lower flange should be increased whereas the upper flange only needs to provide the needed bond.

The forces are transferred trough a primary and transversally arranged secondary grid of girders towards the supports. Those stand at a standardised span of 16.50 metres in longitudinal direction. The supports are planned to be realised as concrete filled composite pillars with a rectangular square-section and they directly support onto the bed rock. In the areas around the openings (there are two in every section) the main girders have to be connected to frames. Here as well, the composite construction helps to equally transfer the forces around the openings.

Cubes

Bridge construction The bridge, meaning the construction on which the freestanding shopping cubes are erected, is to be realised in a steel composite structure. The combination makes use of the different strengths of the two materials steel and concrete. Therefore it offers a number of technical and economic advantages compared to steel frame constructions or monolithic reinforced concrete.

Thrust resistant joints allow the composite structure to work as one part.

In the horizontal parts, this bond is reached via welded stud shear connectors that are welded onto the I-sections of the steel girders. As the neutral fibre now shifts from the central part of the I-section further up it is more economical to adapt the square-section to this new proportion and to let the concrete instead of the steel transfer the compressive force. In a composite

The cubes are to be built as dry-constructions inside supporting steel frames. The goal is to be able to easily relocate and change them over time. Their faรงade is meant to be constructed as curtain walls. The choice of a specific cladding material and its colour is left to the renter. Each company can adapt the appearance according to their cooperate identity. In this way, a higher variety, comparable to the one on a grown market is achieved.

External faรงade The external glass faรงade has a maximum height of 10 metres on a length of fife metres. In this area the mullion-transom system might be doubled if needed.

Else, the height of the faรงade varies between three and five metres on top of the cubes.

Aesthetically, a maximum of translucency is reached by setting back the posts and allowing them to stand free.

In a next step, the gained static depth is cross-braced with wires. By that measure, a soft support, which is favourable to counter resonances, can be achieved at the same time. Horizontally, only elastic joints separate the glass planes. Similar to the vertical bracing, floating columns between the posts could help to minimize the impact of wind to the structure.

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Helsinki Central - Mobilityhub & Market Square

Perspective section: Composite corstruction, double-V-supports, faรงade with back-set construction layer.

Cost effectivenesss and construction sequence

Cost Effectiveness and Construction Sequence Advantages that arise from the different design decisions The construction can be realised according to the following sequence. After laying the foundations the steel construction of the bridge follows. During this short part of the construction sequence, the station operates only partly. Once the prefabricated frames are in position, they serve as scaffolding for the formwork. After the concrete is cast inside the composite construction of the supports and the ceiling, the V-supports are brought into position by a truck-mounted crane and the intermediate tube-parts are inserted right after.

The freshly finished bearing structure of the bridge then serves as work space and storage area for all further construction. After less than a week, all train connections can take up their service again without further interruption. When all formwork carriage and falsework are set in position, the first section of the girder grid will be installed. Due to the Zollinger technique the structure will be rigid enough, and the further construction could

advance without falsework. When the main construction is done, a structural batten, the insulation layer, a roof membrane, the rafters, a transversal batten and an open cover batten will follow. As the cubes are meant to be realised as drywall constructions within the thermal envelope the faรงade needs to be finished before.

In a second phase, the underground bus terminus as well as all landscaping would be done. The City Tunnel which is planned to be drilled independently into the bedrock within a depth of 16 metres is foreseen to be realised until 2015 but can also be connected to the Mobility Hub at a later point in time.

The heating of the building could be realised via the existing local heat distribution network. As a more sustainable alternative an efficient heat recovery system could be installed in the nearby wastewater treatment facility, which is constructed below the surface.

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Helsinki Central - Mobilityhub & Market Square

On the way from the main station to the new Mobilityhub we pass the relocated bus terminal

Annex

Annex Bibliography

Photo Credits

Urban Guide Helsinki, Tuomas Rajajärvi (Hrsg.), Helsinki City Planning Department, 2006 Tailwind Helsinki Horizon 2030, Helsinki City Planning Department, 2010 Finlandiapark, City of Helsinki, Economic and Planning Centre, Development Division, 2007 Library Strategy 2010, Policy for acces to knowledge and culture, Publications of the Ministry of Education, 2003 The Heart of the Metropolis, Helsinki Central Library, Architectural Competition 2012-2012, Competition Programme, City of Helsinki, 2012 Modern Construction Handbook, Andrew Watts, Springer-Verlag Wien, 2010 Space Syntax Analysis, Bauhaus Universität Weimar, Professur Informatik in der Architektur - InfAR, Script Schneider Bautabellen für Ingenieure, Werner Verlag Neuwied, 2006

City Map 1909: http://www.flickr.com/photos/skunkki/2283709976/sizes/l/in/photostream/ City Map 1841: http://www.hel2.fi/kaumuseo/helsinkiinframes/kaivopuisto/kuvat/kartta1841osasuurennos.jpg City Map 1817: http://tallaaja.viuhka.fi/wp-content/ uploads/2010/03/helsinki-suunnitelma1812.jpg City Map 1815, Anders Kocke: http://www.helsinki200.fi/en/imagecache/original_lightbox/uploads/ main-images/anders_kocke_1815_b.jpg HDR in Helsinki: http://www.blogforphotos.com/hdr-inhelsinki/ von Akseli Niemelä Masterplan 2002: http://www.hel.fi/hki/ksv/en/ Town+Planning/Master+Planning/Master+Plan+2002 City Plan Alvaar Aalto, 1961: http://www.helsinki200. fi/en/helsinki-1812-2012/1961-architect-alvar-aaltotown-plan City Plan 1912 Eliel Saarinnen: http://www.helsinki200.fi/en/sites/default/files/imagecache/original_ lightbox/uploads/main-images/3420-16.jpg Topographic Map Helsinki “Senate Map Series” 1886: http://ichc2013.fi/wp-content/uploads/2011/04/ Helsinki_1.jpg Klimate of Helsinki: http://climatediagrams.com/europe/finland/helsinki.htm Klimate of Helsinki: 1981-2006 http://finland.fi/ Public/default.aspx?contentid=160033&nodeid=417 99&culture=en-US#!prettyPhoto Meteorological Data1981-2010: http:// en.ilmatieteenlaitos.fi/normal-period-1981-2010

Magazines Ingenieur Holzbau, Sonderdruck Bauen mit Holz, 6/1999, p 2 DBZ Deutsche BauZeitschrift, Kapelle in Turku, 7/2006, p 30-35 Zuschnitt, Holz Trägt, Unterm Blätterdach, Nr. 38 2010, p 14-15 DETAIL, Bibliotheken, Bibliotheken als Informationslandschaften, 3/2005, p 150-154

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