advertentieThe works on the A4 and the 2nd Coentunnel, which started on July 11 and 12, 2025, are progressing well and on schedule. Traffic disruptions remained within expectations, thanks to road users adjusting their travel behavior. Below we will elaborate on the first period of both projects and look ahead to the continuation.
A4
On the A4, an underpass (culvert) for water has been replaced by a new concrete culvert under the road towards Amsterdam. Due to the project Replacing bridges and viaducts A44, where the detour route runs via the A4, the replacement of the culvert has been brought forward.
Experienced Traffic Disruption
Together with our partners (other road managers and emergency services), we monitor the situation on the road daily. It turned out that the traffic disruption in the first period remained within the expected maximum of 1 hour, both on the A4 and on the smaller roads nearby. At certain times, there were 10 to 15 percent fewer cars than normal. A nice first step! If more people adjust their travel behavior, we can further reduce the inconvenience together.
On July 15, an accident occurred, causing the road towards Amsterdam to be completely closed. This resulted in about 60 minutes of delay. Such incidents show how vulnerable the situation is, especially when road work is also taking place.
In the coming days, the temporary lanes will be adjusted. The 6 narrowed lanes towards The Hague will be moved to the road towards Amsterdam. We will do this at night to cause as little disruption as possible.
Expectations for 2nd Phase A4
In the 2nd phase of the works on the A4, there will be more closures, making it busier, also on the surrounding roads. This will also affect the accessibility of Schiphol during this holiday period. Therefore, we also call during the 2nd phase: do not travel, travel differently, travel together. Various discount actions for public transport and shared transport are available through Amsterdam Bereikbaar.
2nd Coentunnel
The works in the 2nd Coentunnel are also progressing well and on schedule. The replacement of the software went well. Old systems such as lights and announcement and ventilation systems have been dismantled and removed. We have also started applying a new coating to the walls and ceiling panels.
Experienced Traffic Disruption
On the highways, the disruption from the works was as expected, between 30 and 60 minutes of delay. At 2 locations outside the detour route, there has been significant delay. At the Hempont, where between 12 and 20 vehicles fit per crossing, there was a significant traffic jam of 1.5 km. Therefore, we deploy extra traffic controllers and there are signs advising: Avoid the ferry. One of the 2 supply routes to the ferry has also been closed. The ferry is primarily suitable as an alternative for scooters and bicycles, not for cars. With the closure of the Hemweg for regular car traffic, the underlying industrial area is again accessible.
On the S102 in Amsterdam, from Sloterdijk station to the IJ tunnel, it was busy. This was partly due to the works on the S103/Haarlemmerweg. There is now less traffic disruption since the S103 has reopened, but we are keeping a close eye on the situation.
What Can You Do as a Road User?
We have seen that it really helps if people do not travel or travel differently. So continue to choose consciously how and when you travel. Work from home if possible, travel outside peak hours, arrange to carpool, or take the bike or public transport, for example with the discount actions from Amsterdam Bereikbaar . From August 25 to September 12, 2025, extra buses will run between Zaandam and Amsterdam Sloterdijk and from Purmerend. With the bus, you can travel back and forth through the 2nd Coentunnel.