Copenhagen Metro, Line M4 (Sydhavn)

Doubling the Copenhagen metro’s capacity – that’s the target for the network-extension programme in the Danish capital on which VINCI Construction Grands Projets is deploying its expertise in underground works. Our consortium was awarded the design-build contract for the Copenhagen metro’s fourth line. Works include: two tunnels each 4.4 km long (bored using earth-pressure TBMs), civil engineering for five underground stations and switching shafts, sub-trades, electrical and mechanical systems, architectural interior works for the stations, and ventilation in the tunnels.


This southbound extension of the underground system in Denmark’s capital (named Sydhavn or M4) will be connected to the main ring line (Cityringen) and opened for service in 2024. The new M4 line will complement the initial lines, M1 and M2, which are currently in operation (total length of 20 km) as well as Line M3, also under construction (with service entry set for 2020).
Once these projects have been completed, the capacity of Copenhagen’s underground system, featuring conductor-less trains, will jump from 240,000 to 460,000 passengers a day.

Technical overview

The southbound extension of the Copenhagen metro system is part of an urban reconversion project. On the surface, station and shaft sites are diverse. The line’s configuration is mainly in two parts: the first part consists of artificial fill embankments (residential buildings under construction) and in the second part, office and residential buildings have already been built.
Both tunnels will have an interior diameter of 4.9 metres and an exterior diameter of 5.5 metres. Boring operations – mainly through limestone – will be carried out using two earth-pressure TBMs. Locally, the TBMs will cross the Carlsberg fault, which is well known in the region. Each TBM will be serviced by trains. In addition, a conveyor belt for each tunnel will be used to evacuate mucking. Daily environmental tests will be conducted, and a buffer loading zone will be used to store mucking until pollution analysis test results are available.
The five station sites (three of which are very deep below the surface and two moderately deep) will be excavated in glacial deposits and/or fill embankments for the first few metres and in limestone thereafter. This will mainly be an open-pit construction process carried out on the sheltered side of a secant-pile wall. One of the objectives is to minimise the lowering of the groundwater level behind the secant piles. Groundwater must be maintained at its current level outside the excavation area so as not to jeopardise the foundations of existing buildings.
The electrical and mechanical systems will involve installing 11 lifts and 48 escalators, 14 ventilators to aerate the tunnels, air-conditioning, fire protection (pumping station, 10 km of piping, 300 hydrants), drainage, flood protection, electrical distribution, lighting, fire detection, and SCADA.

 “We won the call for tenders in consortium with out partner Hochtief. The client has multiple expectations on this project, including compliance with the plans and timetable, respect for local residents by minimising nuisances, competitive pricing, environmental protection, implementation that safeguards the groundwater network, and high-quality architecture in harmony with the existing stations,” says Sébastien Bliaut, Director, Northern Europe sector.


With this new project, the client (a consortium consisting of Denmark’s ministry of transport and the municipal authorities of Copenhagen and Frederiksberg), is striving to further the development of an effective underground system to provide the city with better service.
Thanks to this new design-build contract, VINCI Construction Grands Projets is consolidating its presence in Denmark, 18 years after delivering the Øresund tunnel and two years after being awarded the Femern tunnel contract. VINCI Construction Grands Projets is renowned for its expertise in transport infrastructure, particularly underground systems around the world, including: the Cairo metro (Lines 1, 2 and 3 since 1981), the Shatin to Central Link line of the Hong Kong metro, London’s Crossrail, and the Paris metro.

Project participants


Project management

Key figures

Implementation dates
March 2018 to June 2024

Tunnel: length (beyond stations): 2 x 3,960 linear metres, excavation tunnel: 210,000 m3, segments: 39,750 m3

Earthworks: 514,000 m³

Stations: civil engineering works: 13,200 m³, secant piles: 56,500 linear metres, concrete: 73,800 m³, formwork: 101,000 m², reinforcement: 16,200 t, waterproof membrane: 54,500 m², concrete coating: 13,200 m²

Cairo Metro Lines 1, 2 and 3