‘We’re building the A10 tunnel section by section'

Ideally, the kilometre-long tunnel would be built consecutively bit by bit, in around 40 sections 25 m to 30 m long and 30 m wide. That works the fastest. ‘But in this busy area, it’s important that the station and surrounding buildings always remain accessible’, says Frank Schuitemaker from construction firm VolkerWessels. ‘That’s particularly challenging on the narrow north side of the station. Having a 30 m wide construction pit there would swallow up all the public space. So we’ve come up with a different solution.’

To the north of the station, where the traffic heads west in the direction of the De Nieuwe Meer junction, we are therefore dividing the tunnel into two long, narrow strips roughly half of the width. We are first building the half on the side where the office buildings, such as the WTC, are. When that has been completed, the kilometre-long strip alongside the tracks will follow. According to Schuitemaker, phasing the work in this way has its advantages: ‘As a result of this, the construction pit is only half as wide and there’s enough space left over during construction for users of the area and our own logistics.’

The reason why we are starting to build the tunnel on the side adjacent to the office buildings is because of the structure of the tunnel. It consists of a main tube with four lanes on the station side, a central tunnel channel with evacuation route and maintenance corridor and a narrower tube in which there will be two lanes for local traffic. In other words, several ‘tunnels within a tunnel’. We are starting construction on the central tunnel channel and the tube for local traffic on the side adjacent to the office buildings. This is because the central tunnel channel will also need to support the roof of the main tube with four lanes. This is why that main tube can only be built later.

There is only limited space there, especially between Parnassusweg and Zuidplein. This will create challenges when the existing entrance to the station is being thoroughly renovated starting in 2027 and the new Brittenpassage is being used instead. We also plan to apply the ‘walls-roof method’ there. Schuitemaker: ‘In that case, we won’t be digging a construction pit, but will first build the tunnel walls and insert foundation piles into the ground. We will then build the roof on top of that, enabling pedestrians to make use of the street above it while we continue to dig the tunnel underneath and build up the tunnel floor and walls’.