The spectacular 3D drawing in Eduard van Beinumstraat shows where we will be building the A10 Tunnel over the next decade: several metres below ground level and between the A10 and the adjacent buildings. There will also be a tunnel tube on the south side of Amsterdam Zuid station, but it is on the north side where space is particularly limited for a construction pit measuring a kilometre long and 30 m wide. ‘Between the tunnel construction pit and the A10, space will soon be limited to just 3.5 m, with as little as 2.5 m leeway at the tightest point on the north side.’
Tracks and A10 closer together
Marc Taken, Zuidasdok design manager explains the situation. ‘Things are already tight, and before that we first need to move the A10 slightly closer to the tracks in 2027. On the south side, we’re only doing this to the east and west of the station, whereas we’re also moving the entire section alongside the station on the north side. It’ll be the first thing that people notice when the tunnel’s being built.’ On the north side, there is only just enough room for the 30 m wide tunnel, in-between the A10 and the buildings. Taken: ‘By moving the orbital ring road further away from the buildings and the construction pit, we’re killing two birds with one stone. First of all, we’re creating the space we need to build. We also don’t need to close the A10 during the work every time, because it’ll always be at a safe distance.’
Use of space
We are also creating space underground, as colleague Frank Schuitemaker from construction company VolkerWessels explains: ‘Such a huge construction pit at the heart of Zuidas is definitely quite a challenge, and not just because of the underground anchors, cables and pipelines.’ He points out the embankment alongside the A10 on a map: ‘After moving the A10, we’ll also be removing what’s left of the Atrium garage, including the underground basement floor and foundation piles. Were currently assessing how much space we need for that; will there be enough room for manoeuvre to take out the old piles or will the viaduct above Parnassusweg get in the way?’
Tolerances
According to Taken, this is not the only tricky calculation facing the designers: ‘On paper, the sheet piling for the construction pit will be inserted upright. However, in practice, 25 m sheet piling will never be completely level, which is why we need an additional 10 to 20 cm of space underground. In construction, these kind of deviations are referred to as tolerances. ‘Tolerances for inserting sheet piling, however small, have consequences in terms of where exactly within the construction pit we can start on the tunnel wall and the carriageway. That’s why we need to calculate this with the utmost precision.’
Station and buildings accessible
Ideally, the kilometre long tunnel would be built consecutively bit by bit, in sections 30 m wide and 25 m long. That works the fastest. ‘But, in this busy area, the station needs to remain accessible and the same applies to the surrounding buildings. On the south side of the station, where there’s slightly more space, that’s easier to do than on the north side’, says Schuitemaker. ‘Having a 30 m wide construction pit there would swallow up all the public space. That’s why we’re cutting the construction pit in two lengthwise on the north side and building the half of the tunnel on the side where the office buildings are first. As a result of this, the construction pit is only half as wide and there’s enough space left over for users of the area and our own logistics. We’ll build the other half of the tunnel after that.’
This is the second in a series about the design of the tunnel in the A10 Zuid and about the techniques and challenges involved. The first article was about the construction team working on the design the construction team working on the design.
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