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Expanding the metro infrastructure in Europe


Published on: October 26, 2023

Expanding the metro infrastructure in Europe

Public transport is a cornerstone of sustainable urban development. For decades, Sweco has made a significant contribution to the transport and mobility infrastructures of some of the largest and most challenging metropolitan areas in Europe.

To meet the effects of urban population growth and the increased demand for transport and mobility, new metro lines are being built and existing lines are extended through visionary and ambitious infrastructure projects issued by municipalities in several European countries. From Finland to the Netherlands, passing through Sweden, France and Belgium, Sweco’s engineers and experts have been commissioned to redesign, optimise and construct the expanding metro and other rail-based infrastructure of highly urbanised areas.

Sweco awarded several contracts for Stockholm’s new metro

Stockholm’s metro handles over 1.1 million passengers daily. To meet the needs of Stockholm’s rapid growth, the Stockholm Agreement was signed in 2013 between the government, the City of Stockholm, the City of Solna, Nacka Municipality, Järfälla Municipality, and what was then Stockholm County Council (now Region Stockholm). A decision was taken to expand three metro lines and build a total of 78,000 new homes in the four municipalities. Since then, more lines and stations have been added, and the entire extension now comprises of 18 stations and 130,000 new homes.

Since 2014, Sweco has been working on the seven stations on the Blue Line’s Nacka and Gullmarsplan extensions. In 2022, Sweco won additional contracts in connection with the expansion of Stockholm’s metro between Fridhemsplan and Älvsjö, where a new metro line is being constructed.

New metro connection to Nacka and Gullmarsplan in Stockholm

In 2014, the joint venture between Sweco and TYPSA was commissioned by Region Stockholm to design the new section of the Blue Line: the metro to Nacka and Gullmarsplan. In 2030, Nacka and T-Centralen will be connected by 11 kilometres of new tunnels and tracks – part of the largest investment in the Stockholm metro in modern times.

The new metro line to Nacka and Gullmarsplan will start at the existing Kungsträdgården station and will run through bedrock under Saltsjön, an inlet of the Baltic Sea in Stockholm, with one of the stations, Sofia, at a depth of 100 metres below ground. The track will run through an underground, underwater tunnel and split into two branches below eastern Södermalm – one going towards Nacka and the other towards Gullmarsplan and South Stockholm. The new Sofia station will be served by both branches, both of which will be part of the Metro’s Blue Line.

Four new stations will be built along the line to Nacka: Hammarby Kanal, Sickla, Järla and Nacka. The line to South Stockholm will have a new station at Slakthusområdet. At the Gullmarsplan station, a new platform will be constructed below the existing station. The South Stockholm branch will be connected to the existing Hagsätra branch (currently on the Green Line), just north of the Sockenplan station.

It’s unique to have a project that so clearly advances the city’s development. The new metro line will fundamentally change Stockholm and create a host of new opportunities for everyone who lives here. This is a key driver for all of us who have the privilege of working on this project.” – Axel Werner, Sweco programme manager, metro to Nacka and Gullmarsplan.


  • Location: Stockholm, Sweden
  • Client: SLL, Region Stockholm
  • Services: Legal documentation to secure planning permission, Environmental impact assessment, Groundwater and hydrogeological analysis, Content and summary of public consultation, Social impact assessment, Design approach, Conceptual design, Visualisation, Detail design, Tender documentation, Support during construction
  • Tunnel length and stations: 11 km new metro and 7 stations
  • Original order value: SEK 700 million

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Rendering of people outside a subway station
People in a subway station

New metro line Fridhemsplan – Älvsjö in Stockholm

A new line between Fridhemsplan and Älvsjö, with six stations, is being built as part of Region Stockholm’s metro expansion. The new line will support the construction of 48,500 homes and will be instrumental in fundamentally altering Stockholm as we know it. Sweco’s work includes designing attractive and safe stations, drafting the legal documentation to secure planning permission, and conducting an environmental impact assessment (EIA).

Functional, attractive and accessible

Sweco’s assignment tasks include determining the exact location of the stations and making them functional, attractive, accessible and traveller centric. The location of the entrances and their relationship to the existing urban environment as well as planned buildings is key to achieving a good result. The assignment encompasses the preparation of system documents for the new line’s stations at the high-traffic interchanges at Fridhemsplan and Liljeholmen as well as the conceptual design for the connections to the existing stations. It entails working on the extension’s entire environment, from passenger spaces to subterranean installations and structures. Matters concerning design are also included in the client delivery.

Evaluating environmental impacts

Sweco has also been entrusted with the important task of evaluating any environmental impacts and preparing the documentation for the environmental impact assessments. This includes investigating and assessing the impact on surface and ground water, and disruptions during the construction phase. In the project that handles the planning process, documentation is produced for the consultation and legal documentation to secure planning permission. Social values such as security, sustainability and safety are being analysed during the process.

I hope that the stations will serve as catalysts for the transformation of Stockholm as we know it, and that they’ll be positioned to create maximum benefit in their contexts. Value creation in our daily lives and shared spaces that are easy to use and that we feel proud of– that’s what I hope for and work for as an architect at Sweco. – Christian Lindqvist, Sweco architect and co-ordinator of station design


  • Location: Stockholm, Sweden
  • Client: SLL, Stockholm Region
  • Sevices: Legal documentation to secure planning permission, Environmental impact assessment, Groundwater and hydrogeological analysis, Content and summary of public consultation, Social impact assessment, Investigations, Pre-concept design, Design approach, Conceptual design, Visualisations
  • Tunnel length and stations: 7.8 km new metro and 6 stations
  • Original order value: SEK 96 million

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Line schedule subway
People on subway station

Länsimetro line from Helsinki to Espoo

Länsimetro is the largest infrastructure project in the Helsinki Metropolitan Area. The first phase of the 21-km metro tunnel from the Ruoholahti district of Helsinki to Matinkylä in Espoo was completed in 2017. The second phase to Kivenlahti in Espoo was completed in 2022. Nearly 4 million cubic metres of rock has been blasted in the middle of the urban environment. The end result is 21.2 kilometres of tunnel, 13 stations and thousands of parking spaces for cars and bicycles. During peak periods, some 1,300 people from hundreds of companies have been working at the site.

Sweco is the largest partner involved in the project management and construction arrangements of the Länsimetro project. Our responsibilities include procurements, management of planning and worksite supervision. Jaakko Naamanka, project manager Sweco

New challenges

The Länsimetro line’s modern metro system is so vastly different from that of the original metro network built in the 1980s that the entire construction organisation was faced with many new challenges at the beginning of the first phase. All parameters involved, such as the sufficient width of the tunnel exits, needed to be analysed with special care.

Successful situation management requires high-quality scheduling, target setting and accurate information, For the first time in a public construction project of this size, a situation management model was used to manage the project. Effective project management was based on situation management, where project decision-making is based on real-time and accurate situational awareness. This situation information enables project management to identify deviations from the set objectives as early as possible and to take corrective action. The new section of the metro system will be used by roughly 100,000 passengers a day. As such, special attention has been paid to the safety of the metro, and the monitoring systems are first rate. Travel safety is monitored by 52 technical systems.

We have learned a lot and developed new kinds of operating methods together. For example, there are no organisational boundaries within the Länsimetro project and everyone works in shared premises. This improves information flow, among other things. Ville Saksi, Managing Director of Länsimetro

Matinkyla metro station


  • Location: Espoo, Finland
  • Client: Länsimetro Oy
  • Sevices: Consulting, e.g project management, implementation planning, procurements, supervision, scheduling, cost management, reporting
  • Tunnel length and stations: 12,2 km and 13 stations + underground depot
  • Order value: SEK 180 million

Engineering the major metro extension in Paris

With 200 kilometres of new underground metro lines and 68 new stations, the Grand Paris Express in the French capital is the largest metro project in Europe. The objective is to support urban expansion and make travelling more efficient, reduce traffic, and improve the city´s air quality. Focus is on creating new Metro connections between the city’s densely populated surrounding areas and on making commuting more efficient. The daily travel time is expected to decrease by an average of seven minutes per traveller.

Line 17, part of the largest metro investments in Europe

In 2016, Sweco was commissioned by Société du Grand Paris for overall project management and detailed civil design for the construction of a Line 17, a new Metro line in Paris with five new stations, part of the largest metro investment in Europe today. In 2022, Sweco was assigned a new framework contract to continue our engineering activities until 2020-2032. The line 17 North will cover approximately 21 km of new metro line, of which 6.5 km will be overground and executed as a metal viaduct. The metro line links the Le Bourget and Roissy-Charles de Gaulle airports and runs north from the area of Saint-Denis to Le Mesnil Amelot. It will serve five new metro stations in three departments to the north of Paris, mainly in suburban areas and the Villepinte exhibition center. Line 17 North is scheduled to enter gradually in service between 2026 and 2030. The assignment is carried out in a consortium led by Sweco Belgium.

With Sweco’s long experience in managing and designing major infrastructure projects, we can meet our customer’s expectations for effective expansion that fulfils the objective of improving mobility between neighbouring areas, Erwin Malcorps, President of Sweco Belgium

Rendering of Metro station Triangle de Gonesse



  • Location: Paris, France
  • Client: Société du Grand Paris, public entity responsible for designing and building the Grand Paris Express metro network
  • Services: Design and engineering of 2 new metro stations. Design of the North tunnel crossing international airport Paris-Charles de Gaulle. Knowledge sharing between the 6 partners of the consortium.
  • Order value: €35 million until 2030

Leading engineering advisor for the Metro Noord extension in Brussels

In Belgium, Sweco has been a trusted partner with recognized expertise in several projects involving the extension of metro infrastructure. For the Metro Noord extension of the Brussels metro, Sweco led the temporary partnership Bureau Métro Nord (BMN) entrusted with the feasibility study for the extension between Noordstation and Bordet. Sweco’s engineers investigated different routes for the extension, analysed the technical and geotechnical feasibility in order to determine the ideal route of the metro line and managed the preliminary design.

The Brussels government selected the ‘densely populated Schaarbeek district’ route. This route has the greatest passenger potential and is also the shortest and therefore cheapest of the three route variants studied. The projected route also scored best in the field of technical feasibility. The new 4.36 km metro line has seven stations: Liedts, Collignon, Verboeckhoven, Riga, Linde, Vrede and Bordet. The construction of the new metro tunnel is being done via the drilling of a single tunnel pipe with a diameter of 9.8 metres. The new route, a welcome addition to the overloaded overground tram line, will handle 60,000 passengers per year.

subway station brussel

  • Location: Brussels, Belgium
  • Client: Federal Public Service for Mobility and Transport – Transport Infrastructure Management – Beliris
  • Partners: Amberg Engineering sa, SM Métro, TPFE-Bagon and SM Van Vampenhout-AREP
  • Services: Feasibility study, master plan, preliminary design

Belgian underground depot at impressive scale

The Erasmus metro depot in Anderlecht is located a few hundred meters from the metro station with the same name and is completely underground. Only the administrative building is visible above ground.

Sweco was commissioned with the project management and the entire study of the infrastructure, civil engineering and special techniques for the Erasmus project, including the preliminary design, final design and permit phases. The depot itself is designed for parking and servicing the new M7 type metro trains. It is 900 meters long and can accommodate 23 metro trains and another seven can be maintained at the two work pits, the lifting stand, the three passerelles, the cleaning pits and the 110-metre-long metro wash. That also recycles 80 per cent of the water that makes the metros shine. Two hot-water high-pressure cleaners, a centralised vacuum system and a freight lift capable of moving 10 tonnes complete the system.

When I was offered the opportunity to work on the Erasmus project, I did not hesitate for a moment. Thanks to this project, we are completing a link in public transport, a step that everyone in this building team can be extremely proud of. – Marijke Busselot, Sweco Team Manager Flor 2 Infrastructure

Marijke Busselot, Sweco

The Erasmus metro depot important for the growing number of passengers

The depot is also very important for the growing number of metro passengers in Brussels. Thanks to wider stabling capacities, the frequency of two of the metro lines has increased to 2.5 minutes during rush hour. Erasmus will also accommodate metro trains that will run on a new line in the coming years. The added difficulty was that above-ground traffic had to be maintained for the duration of the construction site. Construction therefore took place in two phases. First, the walls and columns came there on one side and then on the other. This way, car traffic could always pass. Once the roof slab was in place, the staging area was excavated, under the roof slab, allowing traffic to once again use the full width of the avenue.


  • A ground area of more than 30,000 m², 99% of which is underground, with specific construction techniques
  • Foundations from the avenue and up to 30 meters deep
  •  340 columns installed
  • 400,000 m³ of soil excavated
  • 168,000 m³ concrete poured on site
  •  11 km of low-voltage cables
  •  13 km of fire hoses
Two subway trains on new erasmus station in Brussels
The new erasmus metro station in Brussels