Second Coentunnel

VINCI Construction Grands Projets was mandated to design and build an immersed tunnel (1 x 2 lanes and 2 x 3 lanes, 715 m long) and renovate and rebuild an existing immersed tunnel. In addition to the construction of an immersed tunnel (2nd Coentunnel) and renovation of the 1st Coentunnel, the project calls for: 2 new engineering structures, 12 structured to be widened, 13 structures to renovate, 14 kilometres of roadway to build, and noise-attenuation and anti-pollution barriers to install. This project is part of an initiative to double the number of lanes on motorway A10 (northwest section of the ring road) and the access onto motorway A8 northwest of Amsterdam.

BACKGROUND

Amsterdam’s population increased by more than 10% from 1990 to 2013. In only 20 years, the Dutch capital’s population rose from 700,000 to 800,000.
The Coentunnel, located north of Amsterdam, experiences serious traffic congestion since it is a strategic location providing access to Europe’s fourth-largest seaport. Therefore, it was deemed necessary to renovate the first tunnel and build a second one.
The second 5-lane immersed tunnel below the port of Amsterdam is designed to double the capacity of the existing tunnel and ease traffic flow on the ring road west of Amsterdam and toward the northern part of the country.
This 5-year project was conducted by a consortium consisting of VINCI Construction Grands Projets, CFE, and DEME, which were then subsidiaries of VINCI Construction, as well as TBI, Dura Vermeer, and Besix.

TECHNICAL OVERVIEW

The main objective of the second Coentunnel is to improve access to Amsterdam’s northern suburbs and relieve congestion in the city’s port district. The second Coentunnel was built next to the first and, therefore, runs below the Northern Sea canal. The tunnel consists of 4 immersed components weighed down by concrete ballast.
One of the major stakes in this project was to ensure optimal safety and environmental protection. The goal of the project was to develop a tunnel that allows people to get to their destination quickly and safely.That is why the concrete mix used for this structure meets stringent safety standards, including resistance to fire. As a result, potential hazards to people and materials are minimized.Another challenge was to preserve and upgrade a tunnel built in the 1960s while building a new tunnel less than 30 metres away while minimizing soil-compaction risk during the excavation phases. That is why a temporary underwater retaining structure was implemented. The use of a high-inertia retaining wall enabled the dredging of a provisional trench at the bottom of the canal and installation of the immersed tunnel’s components. These components were built in a basin in Barendrecht in southern Holland and conveyed partly by sea to the North Sea despite major constraints associated with marine conditions.
Work was conducted without reducing the number of traffic lanes in the existing roadway network; however, a complex traffic-phasing system was used to ensure continued roadway use.
The addition of traffic lanes to connect the new motorway and the tunnel required the widening of the road platform (backfill on compressible soil).

This project is the critical feature in a set of initiatives designed to extend infrastructure capacity and improve access to the main road network to the north (“Noordelijke Randstad”), thereby resolving daily traffic congestion that has a negative impact on safety and the environment.

IMPACT

The concession-holder Coentunnel Company, a joint subsidiary of VINCI Concessions, CFE, its subsidiary Dredging International, and their Dutch and Belgian partners, officially launched the second Coentunnel in the Netherlands on Thursday, May 16, 2013, with Melanie Schultz Van Haegen, the Netherlands’ minister for infrastructure and the environment, in attendance.
Today, the structure allows motorists to travel in either direction. The 2 tunnels provide a total of 9 traffic lanes, including 2 reversible lanes designed to optimize traffic flow at set times during the day.
The port district, located west of Amsterdam (between Velsen and Ljmuiden), used to be difficult to access by road. Motorists were almost forced to use motorway A10 to get to their destination. Today, the new structure has eased traffic flow, providing better access to the northern districts and the port to the west. The project has also enabled a connection to the new motorway, A5, which bypasses Amsterdam to the west and carries some of the north-south traffic that used to congest the city’s ring road.
In closing, we can say that this project allowed us to renovate the first Coentunnel after building the second one. Following this renovation, this 40-year-old tunnel is good for another 60 years.

Project participants

Client
Rijkswaterstaat (RWS)

Project management
Coentunnel Company B.V.

Key figures

Implementation dates
July 2008 to July 2013    

Concrete
133,000 m3

Noise-attenuation barriers
3,975 km

Anti-pollution barriers
6,816 km

Testimonial

« User safety was enhanced by bringing the old tunnel up to standards through a renovation made possible by opening the way for a second tunnel. We achieved all this without disrupting traffic. ».

Gilles Cachia, Technical Director

Hallandsås railway tunnels

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