The majority of the Länsimetro line runs in tunnels excavated underground at a depth of more than twenty meters, so the fire safety design of the metro’s underground facilities is exceptionally demanding. All available information on passenger safety, fire safety and evacuation safety has been utilized in the design, and automated property monitoring and security systems have been extensively used in the solutions to guarantee the safety of passengers.
The safest subway in the world
Efforts to minimize the risk of a fire starting and spreading in a subway train speeding through its tunnel have been made beforehand as precisely as possible. Fire safety is taken into account comprehensively in everything, starting with the structural solutions of subway cars. For example, the materials of the carriages have been chosen from low-flammability materials and the interior has as little fire load as possible.
In the event of a fire, the metro train is driven to the next station, from which passengers are directed to exit safely. However, if the train has to stop in a tunnel, passengers still do not have to jump onto the rails. A wide exit platform has been built next to the rails to make it easier to get off the train.
Smoke extraction and evacuation routes in the tunnels have been thoroughly thought out. While trains in many metros around the world run side by side in the same tunnel, in Länsimetro they run in two separate tunnels. The tunnels can be isolated from each other with fire doors, which limit the spread of fire and toxic smoke gases from one tunnel to another.
Passengers can access the adjacent tunnel through fire compartmented connecting tunnels. There are connecting tunnels approximately every 150 meters. The distance is based on simulations that have shown that a full train of passengers can be evacuated to safety quickly enough, even from a strong fire, through connecting tunnels placed at this distance from each other. In addition to connecting tunnels, the tunnels can also be exited through the vertical shafts built between the stations.
To ensure the operational readiness of the rescue service, the rescue service has been allocated its own water and electricity points and planned its own access routes to stations and tunnels. Communication between rescue authorities and other personnel is handled by the communication service Virve, which is used in rail transport and the metro in the capital region, with which drivers, orderlies, maintenance, the control room, as well as the authorities and the emergency center can quickly contact each other in emergency situations.
The underground coverage of the Virve network is good, but in the tunnels, the vital communication of the rescue service personnel is also ensured by landlines. Rail carts are placed at both ends of the stations, with which the rescue service can transport equipment and patients along the track if necessary.
Fire safety in metro stations
The fire design of subway stations located on the surface is quite similar to the design of conventional buildings, but several significantly different solutions have been implemented in them as well. Evacuation arrangements and passenger safety were absolutely primary in the design.
Escalators equipped with enhanced smoke extraction serve as the primary evacuation routes of the stations. In the event of a fire, the downward moving stairs stop automatically, and the upward moving stairs continue to operate. In addition to the escalators, the world’s first fire-resistant evacuation elevators installed at the stations serve as evacuation routes. As far as we know, similar evacuation elevators for people with reduced mobility are not in use anywhere else.
Some metro stations are built in connection with shopping centers. The underground spaces of the stations are designed so that pressurized exits, fire doors and automatic smoke extraction prevent smoke from rising from the platform level to the escalators or the shopping center. All stations have an automatic extinguishing system, which quickly binds the heat produced by the fire and limits the spread of the fire by lowering the temperature of the burning surfaces. In the best case scenario, the extinguishing system may even put out the fire before the rescue services arrive.
In addition to fire engineering plans, we have designed e.g. station exit arrangements, exit route guidance and automatic announcements, which speed up evacuation by urging the public to use the nearest exit. We have also designed the principles of the controls given by the fire detectors for various fire engineering systems. The fire alarm system supplied by Siemens is a key part of the metro’s safety, as traffic control and automatic safety and extinguishing systems are linked to the control given by fire detectors.
Our services in the project
The safety of passengers and ensuring the continuity of metro operations in possible fire situations is of paramount importance. Therefore special attention was paid to evacuation safety, enabling the efficient operation and safety of the rescue service personnel, and demanding smoke extraction solutions for underground facilities.
The basic principles of fire engineering design were often advanced by applying traditional dimensioning tables, but the most demanding and significant solutions are mainly based on performance-based fire safety design and computer simulations. There was no need to reinvent the wheel, because most of the solutions applied to the second phase have already been used elsewhere, and they are largely based on the solutions of the first phase. However, there are some deviations. For example, the new stations differed from the type stations defined in the first phase, so many details had to be redesigned.
Our services in this exceptionally challenging project have included:
- redesigning fire safety of stations differing from the type stations defined in the first step (design is based on performance-based fire safety design)
- design based on assumed fire development with simulations and calculations
- fire engineering plans
- plans for smoke extraction
- the principles of controls given by fire detectors
- principles and model solutions of firestops
- inspections of firestop plans
- emergency plan
- statements about different non-standard fire engineering solutions for official approval
- inspection of the fire engineering implementation as a whole
- inspection of documents related to fire technical product approval and implementation
- consulting in fire-technical issues for various designers and contractors
- official approvals for different plans.
KK-Palokonsultti Oy has participated in the fire safety planning of Länsimetro almost from its initial stages. The fire safety planning of the first phase of the Länsimetro was in charge of L2 Paloturvallisuus. Kalervo Korpela of KK-Palokonsultti Oy was at that time involved in evaluating fire engineering plans on behalf of Länsimetro Oy, the third party inspector was VTT. In essential parts the inspection was based on the assumed fire development. In the second phase of the Länsimetro, KK-Palokonsultti Oy was responsible for fire safety planning.
Länsimetro has been a project that has been permanently imprinted on our minds. For example the coordination of information and plans is very challenging in projects of this scale. Even the authorities approached the fire safety plans with exceptional precision and seriousness. The metro was built according to very strict official requirements, which aimed to ensure that the end result would be absolutely safe. The goal of planning the Länsimetro was set to be the safest subway in the world. We believe that this goal has also been achieved.
Länsimetro in a nutshell
The Länsimetro offers a fast and efficient form of public transport to the western parts of the capital region and offers Espoo residents easy access to the central destinations of the capital region. Länsimetro is a part of the Helsinki metro, which connects the center of Helsinki with the eastern districts and the west with Etelä Espoo and forms the basis of public transport in the Helsinki region together with local trains and regular bus lines. Länsimetro’s ticket system is compatible with other public transport services in the capital region.
The Länsimetro is a joint public transport project of Helsinki and Espoo that started in 2003, the purpose of which was to facilitate the movement of the population in the growing western parts of the capital region and to offer an alternative means of transport alongside the bus and tram lines. The original idea was born in the previous millennium, as a metro line similar to the Länsimetro was proposed to be built already during the planning phase of the Helsinki metro in the 60s. In March 1963, the metro committee of the city of Helsinki presented a master plan that contained 108 stations along the 86.5 km metro line extending to neighboring municipalities. At the time, the proposal did not catch on and the story of Länsimetro continued in 1999, when the Espoo city council gave permission to start planning.
After many colorful stages, Espoo’s city government decided in August 2006 to support the construction of a subway from Ruoholahti to Matinkylä. The city council agreed to the project in September of the same year. The Länsimetro master plan was completed in 2007. The cities of Espoo and Helsinki founded Länsimetro Oy, which was responsible for the implementation of the first and second construction phases of the Länsimetro.
Länsimetro was estimated to be completed in 2014, but due to delays and problems with the construction project, the completion had to be postponed for several years. Länsimetro construction work began in Ruoholahti in November 2009, and the excavation work of the first phase was completed at the end of February 2014. The first phase, put into operation in November 2017, included the extension of the metro line west to Matinkylä metro station. There were eight stations on the almost 14-kilometer section: Lauttasaari, Keilaniemi, Otaniemi, Tapiola, Urheilupuisto, Niittykumpu and Matinkylä.
The second phase of the Länsimetro
The project plan for the extension of Länsimetro, i.e. the section between Matinkylä and Kivenlahti, was completed and approved by the city council in 2012. The financing was approved by the Espoo City Council in September 2014, and the actual construction work started in Suomenoja at the Finnoo construction site in December of the same year. The second phase included seven kilometers of new railway line and five new metro stations: Finnoo, Kaitaa, Soukka, Espoonlahti and Kivenlahti. In addition, an underground subway depot was built in Sammalvuori. The second phase was supposed to be completed in 2020, but the date was later postponed and passenger traffic was estimated to start in 2023. However, the connection to Kivenlahti opened faster than expected.
Construction contracts for the metro stations ended in May 2022, and traffic in the second phase started on the third of December 2022. After the completion of the second construction phase, the whole of Southern Espoo (Suur-Tapiola, Suur-Matinkylä and Suur-Espoonlahti) was covered by rail traffic. With the new section and new stations, the length of the Helsinki metro is now 43 kilometers and there are a total of 30 stations along it. The Helsinki metro is used approximately 63 million times each year.
The transformation of car city Espoo into a metro city is expected to accelerate Espoo’s growth and increase investments in the area around metro stations In the future. As a company from Espoo, we believe that in the near future public transport on rails and the strong new construction around metro stations will lead more and more people to public transport and thus have a positive effect on the climate and our environment.
Länsimetro on the map
The Helsinki metro connects the center of Helsinki with the eastern districts of the city and the Etelä-Espoo. The metro operates with two lines, M1 operates between Kivenlahti-Vuosaari and M2 between Tapiola-Mellunmäki. Länsimetro is an extension of the Helsinki metro to Etelä-Espoo. The first phase, completed in November 2017, included the extension of the metro line to the west to Matinkylä metro station. The section has eight metro stations. In the second phase, the metro line was extended with five new stations up to the Kivenlahti metro station, and a new underground metro depot was built in Sammalvuori. The Länsimetro extension opened on the third of December 2022.
Read more about Länsimetro
- Nice infographic about Länsimetro’s fire safety solutions (HS Ideat -supplement 21.3.2022)
- Länsimetro (Länsimetro Oy)
- Meidän piti rakentaa maailman turvallisin metro, ja sellainen se on (Länsimetro-lehti 1/2017)
- Tavoitteena maailman turvallisin metro (Kauppalehti)
- Länsimetro (Wikipedia)
- Länsimetro on täällä (Helsingin Sanomat 2.12.2022)
- Länsimetron jatke avattiin matkustajille (Helsingin Sanomat 2.12.2022)
- Helsingin metro (Wikipedia)