A localization study is the first step toward building a new metro line. It involves identifying one or several alternatives that are technically feasible and provide significant societal benefits over the long term.
The localization study will form the basis for future negotiations on the funding of the metro.
A metro line to the Bromma Airport area is part of the in-depth needs analysis conducted by the administration for metro expansion in collaboration with the traffic administration, focusing on future rail transport. The analysis highlights around 20 potential routes for future development.
The full analysis, including the concept study on a metro to the Bromma Airport area, is available to read here.
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Planning new public transportation involves considering many factors. Where are municipalities in Stockholm County planning to build a significant number of new homes? Where are there – or will there be –capacity issues that cannot be solved with, for instance, more vehicles or smarter traffic planning?
– This is an early-stage study based on what we know today about, for example, housing development plans and the traffic situation. We haven’t yet decided whether metro or light rail is the best option, says Jörgen Altin, senior project manager at the Administration for extended metro.
The study is a collaboration between the two regional administrations responsible for public transportation: the Traffic Administration and the Administration for Metro Expansion. It provides a broad overview of which connections are worth further investigation and why.
A long-term perspective
In the northern suburbs, for instance, many people drive to work – could expanded public transportation encourage commuters to switch? South of the city, Sköndal is growing – could it become a new metro terminus or a station on the way to Tyresö? If Bromma Airport becomes a new urban district, what’s the best way to travel there? The Yellow Line, the Green Line, or an entirely new line? Is a metro line needed to Kungens Kurva?
– There are still many questions, and we are taking a long-term view with this work—where will we live and how will we travel in 15, 30, or even 40 years? At the same time, we now have a well-established organization that can plan and build new metro lines, so I hope that some of the routes we want to investigate further will end up with us at the Administration for extended metro , says Jörgen Altin.
On January 23, regional politicians will receive an interim report on the study.
– In the next phase, we will look at proposed solutions. For these to become reality, funding will need to be secured. This is something the region cannot do alone; it will require negotiations between the state, municipalities, and the region, concludes Jörgen Altin.
Areas for further investigation:
High-capacity public transportation to a potential new district at Bromma Airport
Increased public transportation capacity to and from Norra Djurgårdsstaden
Enhanced capacity for cross-city travel in the northern inner city
Increased public transportation share for cross-city travel in Söderort and between Nacka and Söderort
Increased public transportation share for cross-city travel between Västerort and Solna, Sundbyberg, and Sollentuna
Improved travel time and capacity along the routes of trunk bus lines 4, 5, and 6
Improved travel time and capacity in public transportation between Sickla and Norra Djurgårdsstaden
Improved travel time and capacity in public transportation to Tyresö
Capacity for public transportation to support the expansion of the Sköndal district
Improved travel time and capacity in public transportation from Skärholmen, Norsborg, Alby, Kungens Kurva, and Norra Botkyrka to the inner city
Increased public transportation capacity in the corridor between Botkyrka, Flemingsberg, and Högdalen
Increased public transportation share for travel to Kista, Solna, and Sundbyberg from the northeastern sector
During the spring and summer, freezing has taken place by pumping coolant into approximately 40 meter long pipes in the tunnel under Mårtensdal. The area consists of soft rock, and in order to be able to blast more safely, the rock is therefore frozen to at least -5 °C.
– We have reached about a third of the distance in one tunnel tube and have just started the other, says construction manager Mathias Tisjö Brinck.
This video shows the tunnel and the frozen mountain. Notice ice crystals on the tunnel walls:
It has been a bit of a slow start to this section as we had problems getting the shotcrete to stick to the frozen surface. Now, however, we have found a method that seems to work and hope that the rest will go on without problems.
Unattended train operation means, for example, that no driver’s cab is needed, but the passengers can see the tunnel during the trip. The solution already exists today in many places in the world, with Copenhagen being the closest.
– Exactly which trains we will buy in is not yet clear, but what we do know is that they will be customized according to our needs. Both in terms of number and furnishings, we are planning for the expected number of passengers by 2060. An advantage of unattended train operation is that it is easier to add more trains if necessary, says Johan Brantmark, director of the metro to Älvsjö.
Giant drill
The new yellow line between Fridhemsplan and Älvsjö will be separate from the rest of the metro system. That is why it can be built in a different way.
– The constructions that are underway now are all extensions, where we add some stations to existing lines. Then we need to build for the same type of train and the same signaling system. On the Yellow Line, we can do things differently – and then we must take advantage of the technological development that has taken place, says Johan Brantmark, director of the metro to Älvsjö.
In addition to unattended train operation, the metro to Älvsjö will be built using a different technique than the rest of the metro system – it will be bored with a large boring machine.
Smaller stations
The stations will also be smaller, with platforms 75 meters long instead of today’s 145 meters. This will allow us to run shorter trains with more frequent departures as it is more logical and causal and make the total travel time and waiting time shorter.
At Örbyleden in Hökarängen in southern Stockholm is the the entrance that is used to bring machines and workers down into the tunnel, and take out the blasted rock. The new tunnel will be 2.5 kilometers long and is planned to be completed by the end of 2024.
Groundwater is a major concern when building a tunnel. To seal off water leakage, a technique called grouting is used. When grouting, long holes are first drilled diagonally outwards in the rock in front of the tunnel front. For each grouting session, about twenty holes of 24 meters long are drilled. Then cement is injected into the boreholes. The cement finds its way into cracks and cavities in the rock and prevents groundwater from leaking into the tunnel. This process can take up to ten hours.
In the yellow machine, a so-called grouting platform, the cement used in grouting is mixed. The white bags contain dry cement that will soon be mixed.
When the grouting is complete, it is time to drill holes for blasting. A computerized drilling rig drills up to 250 holes into the rock, with precise length and position settings. It usually takes between five and seven hours to drill all the holes.
Before blasting, workers load all the holes with igniters and explosives by hand. They use a lifting crane to reach the higher holes.Each blast advances the tunnel by five to ten meters.
After blasting, all the blasted rock must be unloaded. After each blasting, workers unload 1200 to 1600 tons of rock. This is a quieter job that can be done at night.
Underground, it is hard to keep track of the blasting direction. That’s why the measurement technician plays a vital role. They measure the tunnel direction and ensure that it follows the right course and shape.
Sometimes some rocks are not fully blasted away. In that case, workers mark the protruding rocks with spray paint. Then they do a small extra blasting before resuming the work as planned.
Then the tunnel needs to be secured. First, workers remove loose stones by scrapping. Then they spray concrete on the roof and walls to prevent new stones from falling down. Finally, they drill long bolts into the rock wall to stabilize it. Then they repeat the whole process from grouting.
The Högdal depot is being expanded
When the metro system in Stockholm gets longer, more trains are needed. The Högdals depot needs to be expanded to accommodate the new trains. A new track tunnel is also being built to connect the depot and the metro to Farsta, so that trains can enter and exit via both Högdalen and Hökarängen. The entire work on the expanded depot in Högdalen will be completed in 2026.
The expansion of the metro system is well under way throughout the Stockholm area. Högdalen in south Stockholm is home to one of the most important construction sites for making the new metro system a reality – this is where the Högdalen Depot is being expanded to handle many of the new trains that will operate the new metro services.
Here, you can watch a video that better explains what a depot is, why this one is being expanded and how it is being done (In swedish).
“Once the metro expansion is finished, more trains will need to be cleaned, serviced and stored overnight. The depots are an incredibly important part of the ecosystem, and without them, we’d have empty tracks and stations because the trains would stop running. The depots are quite simply the heart of the metro system, ensuring that traffic can flow around the metro network,” says Henrik Unosson, project manager for the new metro system.
Come 2030, you can be 100 metres below ground at Sofia station, on your way from the lift from Stigbergsparken towards the platform and the metro services heading south. On this particular day, perhaps you have plenty of time, so you take a good look around. Perhaps you think, “What a great combination, that turquoise wall and gold-coloured letters,” while also wondering who came up with the idea.
“The artists have been involved in the process since back in 2015. They’ve worked closely with the architects and engineers to ensure that the artwork is an integral part of every station. The artwork in Stockholm’s metro system is important, and we’re proud to be continuing that tradition with the world’s longest art exhibition,” says Martin Hellgren, who is responsible for all the stations being built when extending the Blue Line south from Kungsträdgården.
Realistic for travellers
However, the new images do not simply show the artwork. They have been produced from the computer model used as the blueprint for the entire new metro system. They show the scenes as seen from eye level, and the colours and textures have been processed and reviewed by the artists.
“We use angles that are relevant and that provide future travellers with as realistic an image as possible. We also want to show things that we’re asked about, such as how the lifts at Gullmarsplan and Sofia will work,” says Martin.
Now, you’re sitting on a train heading south, that same afternoon in 2030. At Gullmarsplan, you lift your eyes from your screen – you’re soon at your destination – and see just how beautiful the station looks. “I wonder what that’s supposed to represent,” you think, but there’s no time to find out, it’s your stop, Slakthusområdet. Perhaps you look down now, remembering an article you read a long time ago. “The floor really does look like ice that someone’s skated across. I wonder who came up with that idea?”
Here, you can see all the new images and find out the names of both the artists and the artworks.
Sofia
Artists: Peter Johansson and Barbro Westling Name of the artwork: “Flux”
Sofia, mezzanine floorSofia, ticket hall and entrance.Sofia, mezzanine floorSofia, ticket hall and entrance.Sofia – the second deepest platform in the world.
Sickla
Artist: Anna Lerinder Name of artwork: “Utblick och riktning” (“View and Direction”)
Sickla – ticket hall, Sickla station house.
Järla
Artist: Cilla Ramnek Name of artwork: “Direction Home”
Järla platform.
Nacka
Artist: Thomas Karlsson Name of artwork: “Elefanten och Noshörningen” (“The Elephant and the Rhinoceros”)
Nacka – ticket hall at the corner of Skvaltans väg and Vikdalsbron.Nacka – ticket hall at the corner of Skvaltans väg and Vikdalsbron.Nacka – ticket hall in Jarlaberg.
Gullmarsplan
Artist: Jesper Nyrén Name of artwork: “Windows”
Gullmarsplan –mezzanine floor from which you take the escalator down to the platform.Gullmarsplan – way up at Mårtensdal.
Slakthusområdet
Artist: Helena Isoz Name of artwork: “Åkning” (“Trip”)
The Stockholm metro system is being complemented with eighteen stations and thirty kilometres of track.
In 2014, 16,000 Stockholmers voted on the colour of the new line between Odenplan and Arenastaden – and Yellow won. At the time, the plan was for a separate line with shuttle traffic, although this was changed in 2016. Instead, the line will continue south from Odenplan on the same tracks as the Green Line.
“Since then, we’ve discussed internally whether the Yellow Line should be part of the Green Line. Now, though, the Public Transport Administration, which is responsible for the actual metro services, has decided that this is a good time to make this change. On the one hand, we have a new line that needs a new colour, and on the other hand, the time is approaching to start running metro services to Arenastaden. So, it’s a good idea to decide this now,” says Niklas Bergman, head of FUT (Förvaltning för utbyggd tunnelbana), the administration responsible for the expansion of the metro system.
Accordingly, the future metro map is being changed. The Green Line will have a branch to Arenastaden, and the most recently decided line between Fridhemsplan and Älvsjö will be a Yellow Line.
“Since the metro to Älvsjö is a separate line, it’s good for it to have a colour of its own,” says Niklas.
“At the same time, it’s great that the colour that Stockholmers voted for almost ten years ago will remain on the metro map,” he ends.
The decision on the colour does not affect the routes or future services.
Jörgen Altin, senior project manager for the new metro system. Photo: Region Stockholm / NiLaAlLj, Wikipedia
The new political majority’s first budget this past autumn listed a number of possible metro services. On Tuesday 25 April, the Transport Committee within Region Stockholm passed a decision to initiate work on a needs analysis.
“The first thing we’ll do now is gather information. Building a metro service is a major investment, so we must build them in the right places. We’ll look at developments in the region, where people will live and work. We’re looking far into the future, all the way to the 2070s. All projects listed in the region’s budget will be examined, although we won’t be limited by them. Instead, we’ll also look for new opportunities,” says Jörgen Altin, senior project manager for the new metro system.
The draft list of ideas will be refined and prioritised in the autumn of 2023. Which routes the services could take and the impact they would have on travel and investment costs, for example. However, the are many pieces to the puzzle to lay before we can say exactly what will be built.
“At this stage, it’s not really a matter of bedrock quality and the like, those are more important later on. For now, it’s a matter of gathering knowledge about needs and trying different ideas, which we do together with other parties, such as the concerned municipalities and other departments within the region,” says Jörgen.
Right now, an 18x18 meter square can be seen in Jarlaberg. It marks the location of the future elevators that will take passengers up and down between the platform and the ticket hall. To the right, a glimpse of the elevators can be seen in the back.
– Our work is progressing steadily! We have excavated over 60 percent of the rock volume within the expansion in Nacka. During spring, we also completely finished the blasting to the east, says Erik Lindgren, Project Manager for the Blue line to Nacka.
At all end stations in the metro system, the trains need to be able to turn around. In Nacka the tracks will continue past the station to allow six trains to park over night. This eastern part of the tunnels is now completely finalized in terms of blasting.
Construction sites today – nice entrances in the future
Above ground, work continues with ticket halls at the future entrances.
The underground tunnels are to be connected with the ticket halls above ground. In Jarlaberg, the future elevator shaft is taking shape (see picture) and in Järla and Sickla, work is underway with escalator shafts. After summer, work will begin with the escalator shaft outside Nacka Forum as well.
– Today we have large construction sites and it can be difficult to imagine the result. The stations will be completed gradually, says Erik Lindgren.
Installations from 2026
The current construction work – which largely consists of drilling, blasting and civil works – will be completed in 2026. After that, installations of escalators, lifts, tracks, electricity and various technical systems will take place. The station and all associated structures and construction work will be finalized both above and below ground. Traffic start in 2030.
Inside a warm, cosy cabin sits the bolt rig operator Kalle Pellinen. It takes him four minutes to drill a hole, fill it with cement and then insert the bolt. The only thing that can be heard is Kalle’s Spotify list.
“I have inserted bolts manually as well. It is heavy, hard on your back and shoulders and the cement splashes. This machine entails a significant difference, I can only see advantages,” says Kalle Pellinen.
So far, however, there is one experiment which is in progress just over 100 meters under Sofia church in Södermalm, the third consecutive experiment. This series of experiments is a collaboration between the Region Stockholm, the contractors constructing the tunnels and the companies manufacturing the machines.
New way of thinking
“We have learned a lot. It’s not just about bringing in a machine and starting to bolt, rather this entails a new way of thinking and planning,” says Martin Hellgren, Manager in charge of the expansion from Kungsträdgården to Nacka and to Söderort.
Bolting has been mechanised since long in the mining industry but the demands there are different.
“Our bolts should last at least 120 years. Within mining, the period is much shorter. We must make sure that the method is efficient as well as suitable for various types of rocks. Also, the bolts should last their entire life span,” says Martin Hellgren.
Significant difference for the industry
So far the results of the experiments look good. The three experiments will be fully evaluated by the end of the year.
“We want to be involved and lead the technological development in mechanised bolting. If we succeed, it can make a great difference to the industry,” concludes Martin Hellgren.
Experiment 2, in the tunnels under the Hammarby Canal, is a finalist in an annual health and safety competition for the construction industry. The competition will be concluded at lunchtime on Tuesday, March 28.
“We have an exciting period ahead of us. It is a very challenging and unique passage for the expansion of the metro,” says Peter Leiner, Project Manager.
The common method for blasting through the rock is to first seal the cracks in the rock with a cement mixture, a so-called pre-injection. This seals the rock and prevents too much water from leaking into the tunnel. This is followed by drilling and blasting the tunnel and finally reinforcing the rock.
But in one area in Mårtensdal, just to the north of Gullmarsplan, it won’t be as easy. Here the rail tunnels run through a so-called weakness zone, an area with a weaker rock type that makes the work significantly more complicated..
“The measurements we have taken show that theoretically there is around 2.1 metre rock above the tunnel roof but that is too little to construct as usual. And since the area lies at the end of the Stockholm ridge, the soil above the rock has high water transmission. This increases the risk of rock fall and of water entering the tunnel.
Unusual method
It has been known since long that the rock in the area is inferior, thus we have been able to develop and investigate different solutions..
“We looked at various alternative methods and found that the best alternative at this location is to freeze the rock.
The special boring machine in place in the drilling chamber. It weighs 38 tons. Photo: OHLA Sweden
The method involves freezing the rock and the surrounding earth so as to prevent water leakage and ensure that the area holds up better while the blasting is in progress. The method is unusual but has been used on a few occasions in Sweden when it was needed for one reason or the other, such as Hallandsåsen and the construction of the metro between T-Centralen and Gamla stan.
Process of freezing a rock
Step 1: Boring cooling pipes
Before starting the work, a so-called drilling chamber is built, which is an extra large space that is blasted out to accommodate a special drilling rig and other drilling equipment.
The first step is to drill holes for about 40-metre-long pipes that go straight into the rock. The holes are drilled around what will be the tunnel opening.
“The actual drilling will start in March and will go on for about 50 days,” says Peter Leiner.
Step 2: Freezing
The next step is to fill the pipes with a circulating refrigerant in order to bring down the temperature of the soil and rock to at least -5°C. A cooling equipment keeps the liquid cold the entire time. The work of constructing the tunnel starts only after the right temperature is reached throughout the route and at least 2 m outside the tunnel contour.
“We estimate the freezing process alone to take about 120 days. During this period we cannot do much more than control the temperature.”
Step 3: Rock engineering and concrete lining
Then the actual construction phase can begin. The rock is then blasted out with extra small rounds of shots. The tunnel is temporarily reinforced with sprayed concrete in several steps.
After the rock has been blasted and reinforced with sprayed concrete, a permanent reinforcement is formed and cast, a so called concrete lining.
Throughout the construction, the rock is kept frozen. The cooling aggregate can be turned off only when the entire tunnel is blasted out and the concrete lining is in place.
“We perform a precise control over the thawing of the terrain and rock so as to not damage the surrounding or affect it adversely. The work of freezing the rock and building an about 40-metre-long passage is estimated to go on until the summer of 2024.
Facts: Freezing of rock at Mårtensdal
• The area through which the tunnels run consist of graphite.
• The entire route that is to be frozen down is 39 m long.
• The area is to be frozen down to at least -5°C before blasting the tunnel.
• It is estimated that it takes 50 days to drill holes for cooling pipes.
• It is estimated that from the time the cooling starts it takes 120 days before the entire area reaches -5°.
• The tunnel work is estimated to be completed by around June 2024.
Svenska kraftnät's new tunnel for the Anneberg-Skanstull electricity connection is being built with the help of a tunnel boring machine. Photo: Tomas Ärlemo Photography
“We see several advantages. For instance, a tunnel boring machine has a lesser impact on the surrounding, with respect to how far the vibrations diffuse and the amount of water that leaks in during the construction. This is particularly good as we have some really tricky passages to get through. We know that there is a zone with weak rock where we will work in below Mälaren and Årstafältet consists of clay,” says Johan Brantmark, Manager for the Älvsjö metro.
The technique is as follows: a large drill is penetrated through the rock while building a watertight concrete lining. The tunnel is bored from the southern end of the new line to the northern end. In this way the work tunnels are not required either at all the new stations, as is the case for the routes currently under construction.
“Both the methods have their advantages and disadvantages but our compiled assessment today is that the tunnel boring machine is the best for the route between Älvsjö and Fridhemsplan. There is less groundwater leakage than with the drill-and-blast method, and the risk implied in the time-consuming grouting and reinforcement work is reduced,” says Johan Brantmark.
However, even if there is an emphasis on tunnel boring machines, it does not mean that the extension between Fridhemsplan and Älvsjö will be completely blast-free.
“No, the stations will be blasted out using the same technology as the other new metro lines,” says Johan Brantmark.
Each new metro route has its own conditions and various construction methods were investigated even for the routes currently under construction.
“We looked at the possibility of using the tunnel boring machine even during the planning phase of the current project This was before we had received the terms from the environmental judgements with stringent requirements for water leakage. We have this as well as other experience with respect to the tunnel boring machine technique which we will now be using for the new line,” says Stefan Persson, Deputy Head of Administration Manager for the new metro.
At present, all planning is based on the fact that the metro to Älvsjö will be built using the tunnel boring machine.
“During the year, we will continue to work on the planning. For example, we will continue to examine the terrain and the bedrock, assimilate the technical and financial analyses, continue the work on project design and the work on permits and production planning,” says Johan Brantmark.
The final decision on the tunneling method will be made by the end of the year.
The procurements of all major rock contracts are now either complete or in progress. Those in progress are the Hammarby kanal, Slakthusområdet, Järla in Nacka, Södra Hagalund and the underground connection track between the depot in Högdalen and the tracks towards Farsta. All are expected to be completed in the spring of 2022.
– It’s clear that we’re on our way to a new stage. Focus next year is on procurement in construction, installations and BEST – everything that will make the tunnels to a metro, says procurement manager Iveta Sandström.
Iveta Sandström, procurement manager.
Approximately half of the total sum of procurements in kronor is completed. The charts below show what percentage is done, what is in progress and how many are left to do.
The sounds of big machinery cracking loose boulders after the latest blast are both piercing and deafening. Although ear protection will moderate the sound significantly, it is still strong, and the vibrations from the work can be felt in the body.
– But the cab is almost completely sound proof, so the driver can hear very little.
Niklas Broström explains, occupational coordinator for the construction at CRTG, the contractor chosen by Region Stockholm, currently building the three work tunnels for Blue line to Nacka.
Watch the video from the occupational environment round:
Joint occupational environment round
He conducts the regular occupational round together with Linda Nethercott, occupational environment officer for the new metro. Together they evaluate the occupational environment with check lists to ensure that all is done as it should. Today they are at the construction site for the work tunnel at the Skvaltan interchange in Nacka.
– On an optimal day it should seem as if our function is really unnecessary. When we have eliminated all risks in advance, we have done our job right, says Niklas Broström.
Niklas Broström, occupational environment coordinator for the construction at CRTG.
Different roles
Both Region Stockholm and the contractors building the new tunnels are responsible for the occupational environment, but with slightly different roles.
– The contractor is ultimately responsible for ensuring that the occupational environment is safe for those on-site, while I am on the client side with more of a quality control role. I will be out following up and ensuring that the contractor is doing what we have discussed and agreed, says Linda Nethercott.
– The occupational environment is a very large area. In an office it may concern the lighting. The risks are different here.
Risks during tunnel construction
When building in mountains the geology plays a major role, and there is a risk that boulders might fall. It is therefore important to secure the work tunnel.
– We also have many large and heavy machines running, and many people are working here. We try to plan so not many operations take place at the same time. This planning is important to create a secure occupational environment, says Niklas Broström.
Among the longer term risks is the dust inside the tunnels that may cause damage only emerging after up to 20 years. Similarly, prolonged noise is also a health risk that stresses the body in different ways.
– So we have both long-term and short-term risks, for which we have to work with preventive measures all the time. We cannot chance it and must manage the risks and work proactively, says Linda Nethercott.
Linda Nethercott, occupational environment officer at Region Stockholm.
“The cooperation must be optimal”
Both Linda Nethercott and Niklas Broström mention the cooperation as absolutely crucial for ensuring a good occupational environment.
– We cannot do this just in our own way, it is best when we work together. It is important that we are very accepting, that we can trust each other, be honest and can point out shortcomings. The cooperation must be at its best in order to achieve the best possible outcome, says Linda Nethercott.
The expansion of the metro is in full swing around the Stockholm area. In Högdalen some of the most important work is under way to make the new metro a reality – here Högdalen depot is being expanded to accommodate the new trains inserted on the routes.
– More trains will need to be cleaned, maintained and parked. The depots are incredibly important and if they are not around, the tracks and stations would be empty, as the trains would not be running. The depots are simply the heart pumping around the traffic in the metro network, says Henrik Unosson, project manager for the expansion of the Högdalen depot.
Henrik Unosson, project manager for the expansion of the Högdalen depot.
Started as a technician
One of Henrik Unosson’s very first jobs was actually as a technician i Högdalen depot during the early 1990s. Since 2018 he has worked for Region Stockholm for the expansion of the same depot.
– It feels cool to be back where I once started, but now with the focus of innovating and expanding.
The depot situated in Högdalen industrial area was designed by architects Erik Vestergren and Cyril Marcus, and was built in 1957 and 1958. Since then the depot has been expanded and extended on several occasions, and now it is time to do that again.
Maintenance work at Högdalen depot.
– Since the construction of the depot it has never been depleted of people. The metro never stops and it needs constant maintenance and cleaning.
Henrik Unosson explains that just as cars a metro train needs service after a certain amount of kilometres. Some checks have to take place more frequently, while others are performed at slightly longer intervals. And then there are checks that continuously need fixing, when it is required. For example wheels and brakes underneath the vehicle are checked, and in the passenger area ventilation and interior design is checked in order to ensure a nice environment for the passengers.
Map of the expansion at Högdalen depot. Click on the image to enlarge.
This is how the expansion is done
In the depot area, several new buildings will be erected and other buildings will be remodelled. For example, new storage halls will be built, a new cleaning and graffiti removal hall and the existing workshop will be remodelled to fit the new, longer C30 trains. That will be about a doubling of the capacity when the depot can receive around 50 trains, compared to the current 25 trains.
A new tunnel will be built from the Högdalen depot to Hökarängen, thereby enabling the depot to receive trains from both the Blue and Green line (the Hagsätra branch will belong to the Blue line). Adjacent to the tunnel a new storage hall will also be built underground, with space for 11 trains.
During the spring of 2021 new work will commence at Kvicksundsvägen in Högdalen industrial area. At Örbyleden the construction of the work tunnel to be used during the whole construction phase has begun, to remove rubble and bring in machines and personnel to work on the tunnel with tracks and the storage hall. This autumn preparatory work will also commence next to the Green line metro tracks in Hökarängen.
New metro construction area at Örbyleden, January 2021.
Operation and expansion at the same time
– It is a challenge that the expansion work will take place while the existing depot will remain fully operational. This means that the construction period will be a little longer than it would have been otherwise. And since most of the maintenance work on the metro trains take place at night, most of the construction work will happen during the day, says Henrik Unosson.
All the work with the expanded depot in Högdalen is estimated to take around 5 years, and people living, working and being nearby will notice the work through e.g., traffic diversions, transports and sounds from drilling and blast work. When the new storage hall and the tunnel with tracks are ready, they will not be evident above ground.
Greater capacity and new routes
When the new metro is complete, it will be possible to have more traffic on both the Hagsätra and Farsta lines, and passengers in all of Stockholm will be able to take the metro to e.g. Nacka, Arenastaden and Barkarby.
– The expanded depot also means that the entire metro system will be more durable and stable. If something happens in the depot in Rissne, then trains from the Högdalen depot can easily be deployed to servicing the Blue line, concludes Henrik Unosson.
Background
Region Stockholm’s metro expansion administration investigated 15 possible depot solution and has since discussed Högdalen and Skarpnäck as two possible locations. In February 2019 it was decided to expand the existing depot in Högdalen. One of the advantages of expanding the Högdalen depot is that it will become a depot serving both the Blue and Green line.
Since the first major survey was carried out in 2015, the public acceptance of the metro expansion has remained steady in at least 9 out of 10 responders. There are many choosing grades 3, 4 or 5 to the question “What is your attitude to the expansion of the metro?”.
Head of communications Marianne Dunér has worked on several major projects:
– We had expected a lower result now that we are working on all the things that disturb the surroundings. We are seeing a small decrease, but the fact that we get such nice reviews from people living in the vicinity of the construction is both great and unusual, she says.
Click on the chart to see a larger version.
There is a little difference between the different projects. For example are only 6% i Barkarby negative, grades 1 or 2, despite the construction being in full swing. The depot project scores lower, with 12% grades 1 or 2, although no major works have started there.
– We will be looking at the open answers and the answers to other questions in order to evaluate this. But one thing I can think of is that it may be that the usefulness of the metro is very evident for people living in Barkarby, while it is more difficult to see any immediate gain from the depot expansion in Högdalen. Here we need to clarify the usefulness of the depot, such as clean, well maintained trains, says head of communications Marianne Dunér.
The platform area for Barkarby station is getting ready. Follow us 30 metres underground where the passengers will be waiting for the metro in a few years.
Published 23-03-2021
– This is where you will stand and wait to embark on the metro and travel on to Kista or the T-central, or even further, says Peter Dahl, coordinating project manager for Blue Line to Barkarby.
He is standing in the middle of the platform area for Barkarby metro station. In both ends of the large, arched tunnel work is under way, in one end the rock is chipped off with a machine after a blast (bits of rock are chipped off) and in the other end the rock is sprayed with concrete for reinforcement.
Machine chipping off rocks in one end of the platform area, towards the Veddesta exit.
Two exits Peter Dahl points towards one end and explains that it will be the metro exit near the old Veddesta centre.
– The exit will be in a future building near Veddestavägen, he says.
In the other direction the exit will be connected to several modes of transport – metro, regional train, long distance trains, commuter trains and buses.
Peter Dahl, coordinating project manager outside the construction tunnel in Veddesta, where work on the platform area is ongoing.
– For example, you will be able to take the train from Västerås and change to the metro to Kista.
Two years of work The 250-metre-long platform area is 20 metres wide and around 15 metres high, and it located around 30 metres below ground.
– The platform area has by now almost entirely been blasted out, so the rock work is almost ready in this part of the construction. We have been working for approximately 2 years and we can credit our talented construction crew, the designer and our organisation at Region Stockholm for getting us this far.
In addition to the waiting area for train passengers several other spaces are needed. A service area has for example been constructed with space for electrical equipment, ventilation and water drainage.
Planned metro traffic in 2026 At the furthest end after the Veddesta exit tunnels with storage tracks are being constructed for parking the metro trains for service and maintenance when needed.
The entire journey from Akalla to Barkarby will be approx. 4 kilometres long, and according to the plan it must be ready for traffic in 2026.
The government wants to make it easier to use the rubble in an environmentally beneficial way. The Swedish Environmental Protection Agency is now tasked by the government to investigate how to handle this.
– This is an important and positive message for us. I assume that this means that we can handle the rubble as the resource it is and thereby avoid significant additional expenses and a large environmental impact, says Administration Manager Niklas Bergman.
It has long been the norm to reuse rubble from construction projects below ground, such as the new metro. There is a great demand for the rubble, especially for the construction of new roads and residential areas in the Stockholm region. But at the end of 2019 the county council rejected four applications for existing and new rock quarries in the county, referring to classifying rubble as waste.
– This interpretation was based on a very literal interpretation of an EU regulation and a narrow interpretation of the legal concept ”production process”, and would have unreasonable consequences. The issue has not even been tried in EU, and yet it has lead to a new view of rubble in the Stockholm region, says Niklas Bergman.
Should the rubble be considered waste, it must be transported to special disposal facilities far away, hundreds of kilometres out of Stockholm. Building a new disposal facility involves a completely different and much more complicated process, on a much larger scale than to build a rock quarry.
– For our project alone, it would add several billion Swedish kroner, both as direct costs and indirectly as the construction would take much longer, says Niklas Bergman.
– We will also have significantly increased carbon dioxide emissions from the long journeys with heavy vehicles and in the Stockholm region we would be throwing fully usable rock in a landfill and at the same time crushing new stone in quarries, he continues.
The construction of the new metro to Arenastaden requires close cooperation with Karolinska University Hospital. The blast work will be adapted to the sensitive operation.Published 23-03-2021
From Odenplan the new metro work is constructing tunnels to Arenastaden. This will involve work directly underneath Karolinska University Hospital and Karolinska Institute, where many sensitive operations and instruments are located. – We have been in contact with various units there for a long time. Our expansion is coordinated with the entire hospital and the institute. It is a comprehensive plan which enables us to minimise disruption from e.g. blasts, says Loretto Leguisamo Norén, coordinator for the environmental impact of the new metro. Preparations started already when the hospital was built, and the hospital has also taken several measures in areas where sensitive instruments are located. For example, in the X-ray department. – Drilling should not be a problem other than the disruptive sound, but the blasts produce vibrations. That could cause problems for eye surgery and laser treatments requiring precision. We have great respect for this and have devoted lots of time for planning. One way is to work with fixed times for all blasts during the whole time the work is carried out under the hospital. The vibrations will also be monitored throughout and a lot of the equipment with have vibration dampening. – Furthermore, we have installed sound and light signals in the laboratories and the halls, emitting warnings prior to a blast. Already now they are starting to feel the work from the work tunnel below Norra stationsgatan, but we have time to fine tune the cooperation, says Loretto Leguisamo Norén.
Preferably Stockholm granite but never episyenite. That is what the geologists want. Join us as we go down amongst the gneiss, fissure systems, and mountain cracks.
Geologists are carefully studying the rock dawning as the tunnels are blasted into being. Their tunnel mappings are important for how the work will proceed. “The tunnels are blasted in stages of up to twenty meters. After that, we’ll do a mapping before the tunnelling can continue. A mapping takes about an hour and is a collaboration between us, the construction management, and the contractor working on the site,” says geologist Björn Ensterö. Early in the planning of the subway a forecast of the mountain was made, but the mountain can still surprise. “We document and characterize all mountains. We draw in and photograph what rocks are found in walls and ceilings, drawing cracks and groups of cracks and what properties they have. It determines how the mountain is to be handled and reinforced.”
So what kind of rock is the new metro being built in? “Granite can be found almost everywhere. Amongst them Stockholm granite, which is a light grey or slightly red variant. It is massive and has high density. It is a good mountain to build tunnels in, which we are always happy to find, says geologist Jussara Lourenço. Gneiss, which is common as well, contains undulating patterns and layers. That’s good as well, although there are often cracks between the layers. However, all mountains aren’t good mountains for tunnelling. The geologists were less happy when they found the rock episyenite in Barkarby.” “It’s porous and has low density. It’s enough to tap it lightly for it to break, so there we have to reinforce the mountain significantly. We hope that we don’t come across it in more places,” says Jussara Lourenço. Other types of rock that are good for tunnelling are dioritis and gabbro. “Generally the Stockholm area has good bedrock for tunnels.”
Mountains contain more or less cracks. Some cracks contain clay while others carry water and need to be sealed. The picture shows a sawn-off section of rock at the mouth of the work tunnel in Sickla in Nacka.
Sealing cracks and water emanation The density of the rock is largely dependent on the amount of cracks and crack systems. Some cracks are filled with mud, while others contain water, and then the tunnel must be sealed. More cracks mean more work due to having to reinforce the rock with concrete and bolts. “Selective bolting can be chosen if the rock is good – in that case bolts are drilled into the rock in specific places only. If the mountain is less dense, bolts have to be attached systematically, which means more bolts in special patterns,” says Sofie Eskilander. The worst type of rock is crush zones, where the mountain has been crushed together and stretched out making it brittle. “That’s where the mountain crumbles apart completely. We usually talk about granular rock (sockerbitsberg). Crush zones are found, for example, at faults in Gullmarsplan and Södermalm.
Important for the future The work of geologists is important not only in the construction of tunnels, but also for the future. “The tunnels are covered in concrete and sometimes also in materials that redirect leaking water. In those cases it’s our documentation they have to adhere to when the tunnels are to be maintained. If something needs fixing in a certain place, it should be possible to read about what the mountain looks like right there. The new metro has about 15 geologists today, but there will be more, according to Jussara Lourenço. “We will work on more tunnel sections at the same time and eventually also work in shifts.”
Just west of Akalla, two of Stockholm’s major infrastructure projects cross paths with each other. The new metro to Barkarby will be blasted into being five meters under the tunnels for the E4 Bypass Stockholm.
The need to adapt to other underground or built-in facilities is common when building in Stockholm. Good dialogue and early cooperation are therefore important.
When the Bypass tunnels at Akalla were blasted into being, the Swedish Transport Administration adapted the work to the upcoming metro: “We have had good communication throughout, and the Swedish Transport Administration blasted the bottom of the tunnels very carefully on this particular route, so that the mountain remained as intact as possible. We will also make blasts with care right here. In part so as not to damage the mountain, but also to not even risk damaging anything in the Bypass tunnel, says the new metro project leader Martin Brantberger.
That means shorter bursts that take the tunnel forward shorter distances at a time. And we’re not blasting the entire volume of the tunnel. In parts of the roof we use a method called rock fracturing, which is done without explosives, damaging the rock less.
A lot to be considered The distance between The Bypass and the Blue Line to Barkarby, the so-called rock overburden, is at least five meters, but it is enough, according to Martin Brantberger. “We could go closer, too. What we’d have to do in that instance would be to reinforce the mountain further or replace the mountain with concrete altogether.”
The reason that the Blue Line does not go deeper under the Bypass is due to the fact that it should connect to Akalla station 500 meters away. “We can’t have too steep tunnels, so this is as deep as we can go right here.”
Blasts this close to a tunnel where there is interior work going on right now means that there are also work environment aspects to be considered. “Those working on the Bypass are affected if we blast too close to them inside the mountain. The vibrations could make objects crash to the ground, thereby creating potential danger if someone is on a ladder or unprepared at the time. That’s why we have set blast schedules and good communication when we’re as close as we get to each other.
Sweden’s longest escalator, latches, tiles, tracks and power lines shall be ordered. Although it will be several years before all tunnels are even completed, the planning work is already in full swing.
Construction of the new metro is in full swing. But when the traffic barriers are lifted and the ground has stopped vibrating, the work will continue in the ticket halls and underground. Tor Thomassen is the project manager for BEST and installations at the Söder department. BEST stands for “Track, electricity, signal, and tele” and it is Tor Thomassen and his crew who will ensure that the tunnels are turned into metro systems.
“We’ll take over responsibility for the hole in the mountain and make a metro out of it. The track tunnels shall be filled with tracks and cables. The stations will be artistically designed. And at that point we’re on a choice-of-tile level. Directory signs need to be put up so that people will know their way about and find their way. Barrier lines, lighting, heating, and cooling need to be installed. In addition, all lifts and escalators need to be put in place,” says Tor Thomassen.
Sweden’s longest escalator is to be installed at the station in Nacka. With a lift height of 41 meters and 99 meters long, it pokes the West Forest escalator (33 meters in lift height and 66 meters long) down to second place. The world’s longest is said to be in Kiev with a lift height of 66 meters and a length of 132 meters.
“This may even be western Europe’s longest escalator and another 14 will have a lift height of 30 meters,” says Paula Lindström, project manager of installations.
A critical junction
Ordering escalators this long is a bit tricky. There is only one factory in Europe that produces them.
“Additionally, the requirements for escalators this long are really, really tough and we follow the requirements set by the public transport administration,” says Paula Lindström.
The escalators are a critical point. The delivery period is long and they are to be in place only when the station is being decorated. The plan is to start procuring the escalators to Söder in the autumn of 2021.
As soon as we get access to the facility, somewhere around the year 2025, the escalators need to be installed. It takes time and will be a big challenge,” says Paula Lindström.
For Tor Thomassen, the biggest challenge is that all the work with the tunnels and stations are taking place at the same time. Many contractors are to perform different jobs in parallel with each other, and this needs to happen without compromising on the working environment and safety.
“Right now a large group of us are meeting and going through everything activity for activity, month by month, to make sure everything runs smoothly. There’s no space for wishful thinking. We should have reasonable schedules and use what experienced people say as our basis,” says Tor Thomassen.
