USING a car in Copenhagen is becoming increasingly difficult. Bikes and buses have priority on the streets and the city is rejecting calls to widen roads. While the government has stopped short of introducing road and congestion pricing so far, its reluctance to allow one-way traffic on certain streets adds to drivers' difficulties in the city centre.

Car ownership might be on the rise in the greater Copenhagen area - the prestige still outweighing the practicalities - but already only 14% of the city's 1.6 million residents, 600,000 of which reside in the city centre, use a car to get to work or school. This could be about to fall further with the addition of the 15km Cityring to the metro network in mid-2019.

Tunnelling commenced at the end of 2012 and is now 50% complete, encompassing the section running anticlockwise from Nørrebro to Sønder Boulevard and on the 2km branch from the depot up to Copenhagen Main Station. Tracklaying and fitting out of the tunnels is underway on this section while tunnelling continues on the remainder of the project.

CityringThe 17-station Cityring consists of two single-bore tunnels with three crossovers and three construction and ventilation shafts. The project is being implemented through two contracts awarded in January 2011: a €1.6bn civil works contract placed with Copenhagen Metro Team, a consortium of Italian companies Salini, Tecninmont and Seli, and a €700m railway systems contract awarded to Ansaldo STS. This encompasses design, supply and installation of track, power and communications, Scada, platform screen doors, communications-based train control (CBTC) and a fleet of 28, 39m-long three-car driverless trains, as well as the control and maintenance centre. Ansaldo STS will also maintain the system for five years.

Copenhagen is a medieval city and many of its landmark buildings enjoyed by tourists from around the world date from the 17th century. The Cityring will encounter many of these structures and there is significant attention on minimising disruption throughout the project, from the compact design of the stations, to the construction techniques employed.

Mr Guy Taylor, Metroselskabet's project director, says each of the line's 17 stations utilise a station box concept, which is 60m long, 20m wide and on average 25m deep. "The design is elegant, it is very compact and uses every square centimetre but gives a tremendous sense of space because we are building the roof close to the surface allowing natural daylight to reach the platform below," Taylor says, adding that the alignment is designed where possible not to occupy land under public highways which would jeopardises the flow of traffic during construction. "The station size is so small that you can fit them into public yard areas," he says. "It's a problem for the neighbours, but we are minimising noise emissions and legislation requires that they are appropriately compensated."

Excavating in constrained spaces close to potentially vulnerable buildings led Metroselskabet to conduct comprehensive surveys to check ground conditions and simulate the effects of excavation, and the easing of ground pressure on soil before the civil works contract was awarded. Given Copenhagen's coastal location, Taylor says there is particular attention on preventing any major changes in ground water conditions as construction proceeds.

"We pump water out during construction and re-infiltrate it through vertical-recharge wells because we must not lower the groundwater," he says. "A lot of the buildings we are passing by have old foundations, some of which are made of wood, and would quickly rot away if the water drops and they are exposed. We were also careful to avoid interfering with drinking water supplies."

One of the most challenging station projects was at Marmokirken. The 18th century church, which finally opened in 1894, boasts Scandinavia's largest dome and is described by Taylor as "the real hot potato" of the project.

"The footprint of the station sits around it so you are basically building a box which is deeper than the height of the spire within a metre of the foundations, which are not that large," Taylor says. "We have managed this very well and any movements have been very, very small settlements. All of it has been kept within the limits and we have not had any damage at all."

Magasin du Nord, Copenhagen's famous department store, also posed a significant challenge due to the need to construct the new tunnels over the existing metro tunnel at Kongens Nytorv station and beneath the building. To prevent damage to this and other structures, the contractor has deployed various solutions including inserting jet grout blocks to provide a stiff base beneath where tunnelling will take place and to support some heavy load-bearing elements in the building.

"We inject grout through an array of pipes in the ground which are positioned horizontally beneath the building so we can push it back up if it settles," Taylor says. "This is a common technique used a lot in London, and we check it constantly with electronics to keep track of exactly what we are doing."

In addition to the trials posed by construction, Taylor says that Cityring has also faced significant socio-political challenges. Building a new metro line so close to buildings forced Metroselskabet to seek changes to the law to allow it to exceed permitted noise levels in certain locations. Local residents were relocated or compensated financially if they decided to stay, and Taylor says the company and contractors have received substantial political support to enable it to reach a workable solution for all parties.


As construction proceeds on Cityring, Metroselskabet is also now incorporating an extension to Nordhavn into the project. A €150m contract was awarded to a consortium of Züblin and Hochtief in June 2014 for construction works on the 2km underground section of the 3km branch from near Østerport station to the Nordhavn reclamation area, which is home to new apartment buildings and offices, including the current headquarters of infrastructure manager Banedanmark. Construction on the project began last year and is expected to be completed in 2019 with Ansaldo STS again responsible for installation of railway equipment.

Taylor says the contract for the remaining short elevated section and the temporary terminal station will be awarded imminently and it is now likely that the extension will open at the same time as the Cityring. Beyond this the plan is to develop an elevated railway to serve the entire area, which is continuing to expand using spoil from the metro tunnels. The precise alignment is yet to be determined pending a decision to relocate a freight terminal.

A further extension that is currently awaiting tender is the Sydhavn branch project, which will utilise the existing Cityring link to the depot and continue to a terminus at Ny Ellebjerg. Here the line will interchange with S-Train, and main line services, including the new Copenhagen - Ringsted high-speed line.

Construction of the junction box is already underway as part of the Cityring project to avoid disrupting its services, with the Sydhavn branch expected to open in 2023. A further extension of the line is proposed to connect with planned light rail projects in the west of the city, although this depends on the future location of Ny Ellebjerg station given the constraints presented by other lines in the area.

"This project brings the system's annual ridership potential up to about 200 million, so that's a great asset for us as a company reliant on profits for future investment to get more riders on our trains," Taylor says. "We also get the chance to revitalise socially challenged and isolated neighbourhoods by providing better infrastructure, making it a more attractive place to live."

Copenhagen's first light rail project, the DKr 4bn ($US 605m), 27km Ring 3 line is also moving ahead. Metroselskabet appointed a joint venture of Arup and Rambøll in February to provide design services for the line which will run from Lundtofte, the site of Denmark's Technical University, in the north to Ishøj in the south with tenders for construction expected soon. Daily ridership is projected at 43,000 and the line will be served by a fleet of 27 LRVs, although it is not expected to open before 2021. Funding for the project will come from the state (40%), municipalities (34%), and the Capital Region of Denmark (26%).

In addition to other potential light rail projects which will serve the west of the city and provide connections with existing rail services, Taylor says the appetite is growing for an additional metro service to Malmo. He says this will run in tunnel and is intended to relieve pressure on the existing Øresund link.

"The Fehmarn Belt project will produce higher demand for track availability and the Øresund Bridge is already at capacity, so we want to find a way of separating local passenger traffic from freight traffic wherever possible, giving more opportunities for freight and main line trains to travel to the south of Denmark." Taylor says.


High capacity is a hallmark of the existing Copenhagen metro system, which is entirely automated and offers headways of two minutes at peak times.

Unlike the current metro control system which relies on a track circuits, the Cityring will deploy CBTC. Head of systems and operation Mr Chris Cox says this is a big step forward for the network, and while there is nothing wrong with the previous set up, the new project provides Metroselskabet with the opportunity to benefit from updated technologies, including a high-capacity Ethernet-based communications network.

Cox says CBTC will offer greater reliability and headways of less than 100 seconds, which will be beneficial in recovery situations, adding that with fewer ventilation shafts in the new tunnels, it is important for the system to control the number of trains in the sections between stations in the event of a fire.

"It's a very elaborate system and there is a large amount of complex software that is integrated with the tunnel ventilation system, the Scada system, the power supply and traction power supply," Cox says. "If an alarm is activated by a preceding train, the following train is held at the station because it sees the section ahead is potentially obstructed. The passenger information system is also integrated with the CBTC system so what is happening with the service can easily be relayed to passengers."

The line will be served by a fleet of 28 vehicles and Cox says two additional sets have been ordered for the Nordhavn extension. Six vehicles had been delivered by mid-September and another is due at the end of this month. While AnsaldoBreda is again supplying the trains, they incorporate several upgrades, including new fire resistant materials, a new door system, enhanced communications, and a water mist fire suppression system.

"This is quite a novel technology and we have carried out some early tests," Cox says. "It's a pressurised system which carries 80 litres of water and is part of the mitigation concept because of the greater distance between the point of incident and the place of safety."

Copenhagen's network is notable because it operates 24 hours a day, seven days a week. Cox says that with such intensive operation it is essential that maintenance is carefully managed and planned. As a result the plan for the Cityring is to close down one of the tunnels and allow single direction operation during the four-hour maintenance window, while offering a shuttle service on the Nordhavn branch.

"We only have three crossover points so that means we do not have a lot of flexibility," Cox says. "Without that you need reliability so it is very much the focus that this system will be very stable."

The existing lines' current reliability of 99%, which has improved since the installation of platform screen doors at elevated stations, shows that this is a workable strategy. And with the expansion projects currently on budget and on schedule, and construction so far avoiding major confrontations with residents, the new lines are set to be popular additions to the city's growing public transport system.
"We're not reinventing the wheel here but are just making sure that we are not causing problems," Taylor says. "We can all make mistakes which can results in delays. But we try to perceive what is coming and work around that."