Cityringen: the innovative metro in Copenhagen tunnel
A double track loop of 15.2 km which intersects 17 new stations and connects to the current subway and railway system. Cityringen is the name of the new M3 line of Copenhagen metro, the Danish capital that has been representing for years – with motto “Copenhagenize"- the best European example of urban intermodality suitable for bicycles.
The new Cityringen, fully underground and completely automated, can sustain a traffic of 350,000 passengers every day, 24/7 for a total of 130 million users a year. The design goal is that the city must be accessible by anybody from a subway station in the radius of 500 metres. This way, it is calculated to increase the share of users of the public service by an additional 25% with consequent, drastic leaning of the urban traffic and reduction of CO2 emission. The subway loop will contribute to make Copenhagen, the first “carbon neutral” capital in the world by 2025.
The contract of over 2 billion 850 million Euros was awarded to the top Italian companies: Copenhagen Metro Team consortium led by Salini Impregilo for civil works; Ansaldo STS for railway works, signalling, maintenance and rolling stock. GCF - Generale Costruzioni Ferroviarie was awarded the task to build an innovative railway system along the entire track and an additional northern extension of Cityringen.
Metro Cityringen, Copenhagen
Denmark and the subway loop of the century
It is considered as the project of the century in Denmark. Not only because it is one of the major contracts for public works that has ever been stipulated in Denmark. Cityringen loop subway will bring a real infrastructural revolution to Copenhagen: the biggest in the last 400 years, since the famous Christianshavn District was built.
Two twin galleries, of diameter of almost 6 metres, run parallel for about 16 km underground until a depth of 40 metres, higher than the Tower of Copenhagen. The two tracks form a double loop that crosses 3 large “service stations” featuring exchanges and parking tracks and 17 new stations fully underground, excavated to an average depth of 20 m beside monuments, churches, historic buildings, squares and streets among the liveliest and crowded of the city.
The new loop will feature various connection points with the existing intermodal transport system: at Kongens Nytorv and Frederiksberg stations with the two subway lines M1 and M2 inaugurated in 2002; at Copenhagen H, Østerport and Nørrebro stations with the railway network and in particular, the 7 S-tog lines – metro railway networks that connect the city and hinterland.
An additional double section of about 2 km connects the subway link to the CMC, the Control and Maintenance Centre; on an area of 90,000 square metres, there are the Headquarters, offices, washing centre, manoeuvring and parking areas of vehicles. Lastly, a North-East section develops the subway connection for an additional 2.3 km of line towards Nordhavn area.
Below: Cityringen Construction sites in Copenhagen, lowering of GCF portals in the tunnel
The innovative choices for the railway construction.
The railway construction is fully entrusted to GCF. It was opted for two building types. A traditional railway construction technology on ballast was implemented for the ribbing inside the area of the Control and Maintenance Centre (CMC). The only exception is the tracks inside the buildings which are made with an embedded track technology within the concrete floor.
The subway line instead, with regards to the connection section and tracks in the two single loop sessions, was built with the innovative Slab Track technology made with LTV blocks (Low Vibration Tracks) embedded in locking concrete casting.
A building type recently adopted also by the Swiss construction site of Generale Costruzioni Ferroviarie that will look after the railway construction of the Galleria di Base del Ceneri, on the high-speed flat line connecting North and South Europe. “It is a coherent and effective choice – explains Engineer Francesco Costa Medich, from Turin, Director of GCF’s construction site – in line with the design goal to minimize vibrations and therefore, the noise caused by the transit of vehicles below sensitive city areas".
Below: Pre-assembly of the track in CMC construction site. Cityringen Copenhagen.
An innovative construction site: method, organization, machinery.
Building method, process phases, equipment and machinery used: each element of GCF construction site was designed, evaluated and chosen based on manoeuvring spaces, overall sizes of the work and difficult logistic conditions. “GCF team – underscores Engineer Costa Medich – proved to be extremely skilful and flexible in studying and defining in the finest details, with the client, the best building method according to the design. Since the beginning, the goal was to find solutions to minimize risks of lack of production since it is fundamental for a challenging project like Cityringen, to comply daily with the provisional programs despite the great logistic and coordination difficulties”.
Many technical and organizational solutions conceived and developed by GCF for the construction site of the Danish capital. For example, the construction external pre-assembly system that allowed ensuring stock in Copenhagen and therefore, to keep constant the daily production in the tunnel, also during unforeseen situations. The concrete casting procedures and techniques, for which special “portals” were developed that, fed by cement mixer circulating on the already built track, allowed avoiding to pump concrete in the tunnel: “The only possible access points - explains the Site Manager - were consisting of the future stations, 1 km away from each other. This would have implied horizontal pumping for lengths up to 600-700 m: a high risk option that we preferred to avoid”. A similar system, properly modified and “boosted” in terms of power, was adopted successfully by GCF for the high-speed railway construction in the Base del Ceneri Tunnel.
Below: installation and construction of the track
Last phase: construction of the third track
Adjustment of the track and concrete casting before the last phase of GCF’s activity to build the Copenhagen subway: construction of the third track. An additional loop of about 16 km that runs parallel to the track in each of the twin tunnels, feeding Cityringen’s automatically driven vehicles.
Its construction is a delicate and complex operational phase for GCF’s construction site, based on the meticulous prior patting of temperatures detected point by point in the tunnel. “After building the third track - explains the Team leader Gaetano Franciosa - the individual adjustment of each of the 350 joints was calculated on this map that, inserted at a distance of 120 m from each other, will allow compensating the dilations due to thermal changes”.
Cityringen’s construction site is a lively village in the city: 22 external construction site areas that end up in the city centre and over 1,500 employees that work every day in the double tunnel which has a single access point, fairly crowded by manoeuvring vehicles, for the supply of “heavy” building materials. Over 4,000 rails were handled for the railway construction, each mounted on 26 LVT blocks: about 20,000 tons of materials.
The Site Manager, Engineer Costa Medich, has no doubts when asked to mention the most challenging aspect of Copenhagen construction site: “Certainly the great organizational effort required daily to coordinate all stakeholders and relative work programs, synchronising and rendering lean and constant, through the only access door, all the supply and handling operations of the countless machines and large quantities of materials”. Along the "Functional Section" of the Cityringen, subway vehicles are already in operation since a few months for the strict preliminary test phases.
Cityringen, the civil work awarded to GCF
Cityringen, the adjustment phases of the track and concrete casting
Cityringen, Last phase of GCF’s activity: the construction of the third track
Inauguration: a festival for Italian excellence
The new underground railway line Cityringen was inaugurated before a big crowd on Sunday 29th September 2019 by the Queen of Denmark, Margrethe II, at the presence of the top politicians of the Country and city of Copenhagen.
In the Danish capital, 85% of the citizens will have a metro station in the radius of 600 metres. A fleet of 39 driverless trains, completely automated and without driver, will carry up to 75 million passengers a year, with a frequency up to 75 seconds. The work, one of the most important European projects of sustainable mobility that candidates Copenhagen to become by 2025, the first carbon neutral capital in the world, was universally greeted by the media as the “result of the union of Italian excellences in the building and civil works sector (Salini Impregilo, leader), in the railway armouring sector (GCF) and technological innovation sector (Hitachi Ansaldo Sts)”.
The management of Copenhagen metropolitan network will also be entrusted to an Italian company, Società Metro Service A/S, held by ATM (ATM Azienda Trasporti Milanesi) with 51% shareholding and by Hitaci Sts, for the remaining 49%.
Cityringen, the inauguration day and the first trip of the metropolitan loop
GCF in video: work phases of "Cityringen" railway construction
Cityringen Subway of Copenhagen: Additional information
- The intermodal transport system in Copenhagen
- Cityringen: executive phase of the railway construction.
- Excavations and civil works
- The expected benefits for the environment
The intermodal transport system in Copenhagen
"Copenhagenize" is the slogan according to which Copenhagen promotes its urban mobility system at international level. It is based on three elements.
The existing subway. Automatically driven, of Ansaldo Breda type, it was opened in 2002. It features two lines (M1 and M2) that follow a parallel path in the city and are divided at Christianshavn into two different sections, a western line towards the airport and an eastern line towards Orestad. They are 21 km long -10 km in the tunnel, 11 on raised track – and intersect 22 stations. There are 34 trains operating 24/7. The average speed is 40 km/h.
The S-Tog, in operation since 1934, represent the arteries of the metro railway Service. Overall 7 lines in loop for a total extension of 170 km and 85 stations. The average transit frequency is 1 train every 10 minutes; 3 high-speed lines that serve 17 stations of the city centre, reaching a frequency of 1 train every 5 minutes during rush hours.
Bicycles. The main means of transportation in Copenhagen: 140 km of continuous bicycle tracks, raised above the road level and strictly separated from the sidewalks and walkways, make the bicycle the quickest and most efficient means of transportation, therefore the favourite and mostly used. All trains and subway vehicles feature spaces and racks to easily carry bicycles. All stations are equipped with stairs with “grooves” to hand-push bicycles.
Today, 40% of citizens reach work by bicycle. With the new Cityringen in operation, the percentage will grow remarkably.
Cityringen: executive phase of the railway construction.
The first phase, between fall 2013 and summer 2014, with the construction in CMC area for an extension of 4 km of tracks on ballast.
Second phase: construction of the first tunnel section between CMC, Copenhagen H station and Nørrebroparken station: 14 km of single track built between fall 2015 and early 2017. The section is called “Functional Section” since it is already in operation from September 2017- while works are being executed- to test the vehicles in the pre-commissioning phase.
Third phase: completion of the railway construction in the remaining section of Cityringen loop between Nørrebroparken well, Øster Søgade well and Copenhagen H station. The section consists of about 18 km of single track and was built by GCF in May 2017 with double operating phase to meet the deadlines that foresee the conclusion of the works by March 2018.
Fourth phase. In addition to Cityringen loop, the project includes Nordhavn extension to the north-east, which was awarded to GCF with an additional contract. The extension consists of an underground section and an end section on viaduct. It features a total length of about 2,220 m of line, equivalent to an overall length of about 4,500 m of track, and its construction, which began in March 2018, will be concluded by the end of the year.
Excavations and civil works
The two Cityringen parallel tunnels were excavated in limestone at a depth of 40 m, by 4 TBM (Tunnel Boring Machines), each one operated by teams of 10-15 highly specialized workers.
They weigh 800 tons each and they are long 110 m (the size of a football field) and were lowered from the wells and mounted directly in the tunnel. The cutting head of each TBM features a diameter of 6 m and a depth of 11 m; it rotates up to 5 rev/min. 32 hydraulic cylinders push the TBM with a pressure up to 3,000 tons. The feeding speed is 14 m a day.
The TBM, in operation since August 2013, were called as per tradition, with feminine names, choosing the names of the first four telephone stations in Copenhagen that for the first time connected the residents: Nora, Tria, Minerva and Eva.
The tunnels consist of pre-shaped cement loops, each consisting of six segments and 1.4 m long. 130,000 loops were used overall. All the new 17 stations were excavated in the sub-soil up to a depth of 30 m.
Over 3.2 million m3 of soil were removed and transported- with 90,000 fully loaded vehicles – in Nordhavn to extend the seafront and expand the district by over 100 hectares with a new area, the size of 140 football fields.
The expected benefits for the environment
In addition to the special solutions adopted during the railway design and construction phase to reduce vibrations and therefore, sound pollution, the new Cityringen in Copenhagen paid utmost attention to reduce energy consumptions. For this reason, the loop track consisting of two sections follows an undular altimetric path with stations located on small hills: the high position naturally reduces the energy consumption of vehicles when accelerating and braking.
With the opening of the Cityringen, it is estimated that the number of citizens who will choose to walk, use the bicycle and public means of transportation will increase by 75%. 8,800 passengers will use the subway station of the Town Hall square every day.
Each subway vehicle, fully automated, is able to transport 300 passengers. If all 34 trains are full at the same time, it means that 10,200 passengers can be transported in a single run. The commercial operating speed will be 40 km/h and the travelling time for a complete loop will be about 24 minutes.
The Subway is an eco-friendly transport choice for Copenhagen: CO2 emissions are reduced by 75% for each person who uses it instead of the bus; emissions are reduced by 83% if used instead of cars.
Cityringen, conceived in view of full bicycle+train-metro intermodality is fundamental for Copenhagen intermodal transport policy, in addition to the constant implementation of bicycle tracks in the city network, currently long 400 km. Thanks to Cityringen, the ambitious goal established by the CPH Climate Plan 2025 is being reached, meaning to reduce CO2 emissions and transform the city in the first “carbon neutral" capital in the world.