'You don’t want them driving into the construction pit'

‘Look, the nine’s already starting to fill up more’, says road traffic coordinator Kim Robinson pointing at one of her screens. ‘Obviously I mean the A9. Sorry about the jargon’, she laughs. It’s around 10.00 on the morning of Monday, 7 August 2023. It’s almost two days since the A4 and A10 Zuid were closed from the Badhoevedorp interchange to the S109 Rivierenenbuurt access road. During that time, we are moving two huge sections of the roof for the new passenger tunnel at Amsterdam Zuid into position. For eight days, traffic is being diverted via the A9 and the north-western Netherlands’ traffic control centre in Velsen is carefully monitoring whether the diversion routes are becoming congested. ‘Closing the road on Saturday evening went smoothly’, says Robinson. ‘I did see quite a few vehicles stopping along the roadside, but that’s nothing unusual. There are always some surprised motorists checking their satnavs at the last minute.’

Not only for the red crosses

Closing a major traffic artery like the A10 not only has significant local, but also regional and even national impact. It requires an enormous amount of preparation and Rijkswaterstaat is also closely involved in that. ‘People often think that we’re only there to put red crosses above the road at the crucial moment’, says Robinson. ‘But it involves much more than that. It’s our job to ensure that everything runs safely from start to finish. We monitor continuously: are all the systems working? Or is there an overeager contractor already starting to close off the road? Are there any motorists getting out of their cars to remove the fencing?’ And then, after a brief pause: ‘You’d be surprised, but it actually does happen. And, of course you don’t want them driving into the construction pit.’

Induction loops and matrix signs

Slightly later, we are perched on a kind of balcony behind glass, overlooking the entire traffic centre. Beneath us, we can see around eight massive desks, each with around five computer screens and a large display with views from dozens of roadside cameras behind them. ‘Every desk is monitoring a different area. That there is the Coentunnel, and that’s the Zeeburgertunnel. And there’s the A10 orbital ring road.’ Robinson points at one of the camera images showing a clear view of the hole in the A10 Zuid. ‘We receive a lot of information via vehicle detection induction loops (copper wires in the road surface). They tell us how fast people are driving, when something gets stuck and even if there’s someone driving in the wrong direction. By switching cameras, we can quickly see what’s happening. And we can then respond accordingly, for example by adjusting matrix signs over the road, sending out a road inspector or deploying the emergency services.’

Lessons learned from the 2022 summer closure

Fortunately, this has not been necessary so far, according to Niels van den Brink, traffic manager at Zuidasdok. In addition to the Rijkswaterstaat traffic control centre, there is also an operational team closely monitoring the situation. ‘It helps that the closure is happening in the middle of the summer holidays, rather than at the start as in 2022’, says Van den Brink. ‘We also began communications well in advance, which has real advantages. In the early Monday morning rush hour, we had a delay of around 30 minutes at the Schipholtunnel – which is only to be expected and not nearly as bad as it could have been. After all, we’re warning of delays of up to an hour.’ In addition, the team has learnt a lot of lessons from the 11-day closure of the A4 and A10 in the summer of 2022. ‘Back then, we gained a very clear picture of which traffic lights on the diversion routes needed adjustment, by setting them on green for longer, for example. We’ve put that data to good use this year: we’ve adjusted around 50 sets of traffic lights across Amsterdam. We’ve done it in De Boelelaan, for example.’

Visual inspection