Copenhagen has one of the most advanced and cohesive public transport systems in Europe. The Cityringen project forms a new circular line in the city centre and consists of two 17.4km tunnels and 17 new stations (two of which are transfer stations) all at 30 metres below ground level.

From a technical point of view the project was extremely complex, since the city is at sea level. Tunnel excavation was made by TBM. A cut and cover service tunnel was also built for the connection to the operation and maintenance centre.

The fully automated driverless metro system operates 24 hours a day, with a minimum frequency of 100 seconds, guaranteeing efficient mobility for 72million metro passengers a year.

For Copenhagen this new metro line represents a rapid, safe and environmentally sensible means of transportation.

The project involved the construction of 17 stations and 5 shafts, including civil and electro-mechanical works, together with a double tunnel, excavated using 4 TBMs (EPB) with a diameter of 5.80m. The excavation was mainly through calcareous rock with varying degrees of fracturing and, in some sections, loose soil predominately glacial in origin, of varying granulometry, and large boulders. The tunnel lining was built using prefabricated concrete blocks. The project included 4 ventilation, extraction and TBM-assembly shafts, and 1 ramp connecting the maintenance and control centre, built using the cut and cover method. The stations and shafts were constructed bottom up, apart from Marmorkirken Station and the new Havnenholmen shaft .

Challenges of the project

Of extreme importance in building this metro was the capacity to be able to work within a populated urban centre, while drastically reducing any inconvenience for its residents and for circulation, and also eventual risks for the historical buildings near the works. Particularly challenging were the works concerning the station located near Frederiks Kirke (Marble Church or Marmorkirken), an 18th century church, and the fact that the tunnel passes under the 19th century historical site of the main Danish Department store chain, Magasin du Nord, at Kongens Nytorv.​

Client: Metroselskabet I/S

Under the CPH Climate Plan 2025, Copenhagen intends to become carbon neutral by 2025. The metro system – and public transportation in general - supports the aim to achieve carbon neutrality by 2025 as part of the CPH Climate Plan. Thanks to the new line and its connections to the existing network, residents are able to move by foot, bike or public transport for 75 percent of their trips. 

The fully automated Cityringen line is driverless and provides a 24-hour transport system that guarantees the mobility of 72 million passengers a year.

Innovation

The secrets of an ambitious project

Building Cityringen, with its high level of technology and innovation, was not an easy task. Copenhagen Metro Team I/S (or CMT - the fully owned Salini Impregilo - now Webuild Group - company that built the infrastructure) worked for over 8 years to complete the project – quite an achievement if we consider other similar projects in Europe taking into account their different location and conditions of implementation. 

One of the greatest challenges of building Cityringen was having to do it in highly urbanised areas where historic buildings were located. Since the line crosses some of the Danish capital’s most densely populated neighbourhoods with commercial and historic areas, great effort was made to carry out the work without disrupting people’s lives or damaging any buildings. 

An example of this is the case of Magasins Du Nord - one of the city’s landmark buildings - where the tunnel-boring machine (TBM) excavated a mere one and a half metres below its foundations without obliging the shops to have to close. The excavation was carried out using innovative techniques. The TBMs did the tunnels 4.9 metres in diametre at an average depth ranging from 20 to 35 metres.

Sustainability

Focus on people

From the very beginning of the project, the use of local workforce for at least 50% was a priority. The project promoted new employment opportunities, also paying great attention to gender distribution: female employment represents a quarter of the project’s personnel.

Cityringen was built by people from 24 countries, including England, Ireland, Romania, Italy, Bulgaria and Portugal. It was an example of multicultural Europe that not only created thousands of jobs but also displayed the highest level of technical skill in the industry. 

All personnel received training, with courses aimed at developing technical and managerial skills.

Cityringen and the environment

The project oversaw the clean-up of previously contaminated soil in a number of areas. A careful management of chemical substances avoided infiltrations in the water table and an advanced monitoring system ensured that materials used on the project were compliant with environmental regulation. Wherever the contaminated soil was found, a process to treat and remove it was implemented with the greatest care.

• 25,000 tonnes contaminated soil excavated, treated and removed from stations and shafts
• 5,000 hours of planning, supervision and reporting

Safety in the Worksites

Safeguarding safety has always been an imperative for CMT to guarantee the wellbeing of everyone who worked in the worksites. The best international best practices were implemented for safety purposes, while new training and communication initiatives were also provided to make workers more aware of this topic. 

Webuild Group promoted an awareness and training campaign aimed at developing a culture that greatly focused on health and safety issues. 

In 2018, the Lost Time Injury Frequency Rate scored 0 during many months, reaching 1 million worked hours without accidents, becoming a best practice in Denmark. It was a record that demonstrated the high level of attention paid to health and safety. In fact, the accident rate was five times lower than Danish average - further evidence of how the project had always respected the standards of excellence.

Local communities

Building large infrastructure in densely populated urban areas involves many challenges, not only technical ones, but also in terms of interacting with the surrounding environment. Local communities were involved in every phase of the project with the aim of fomenting greater understanding of the complexity of the work and the benefits to be gained from it once completed.

Since 2013, in Copenhagen, specific information campaigns were organized to engage local communities, inviting them to visit our worksites so that the Group could explain the technology used and how the works were progressing.

Among the activities used to promote communication with citizens, a specific email address was provided for reporting purposes, while an SMS notification system was also introduced to inform citizens of eventual extraordinary works impacting upon acoustic pollution levels or mobility.

• more than 40 public events in the worksites
• more than 65,000 visitors