The Piet Hein Tunnel in Amsterdam is undergoing a large-scale renovation. The work involves modifications to the bracing structure, the retaining walls for the sheet pile walls, the central tunnel channel, and the traffic control and technical tunnel systems. The tunnel’s road design does not form part of the renovation scope. The modifications do, however, affect the roads in and around the tunnel, and as such they affect traffic safety.

For this reason, the municipality of Amsterdam asked Witteveen+Bos to conduct a traffic safety assessment and assess whether the work might result in any high-risk situations. Witteveen+Bos employs multiple traffic safety auditors who are certified to assess all kinds of roads, from dirt roads to motorways. Our auditors combine extensive knowledge of the relevant guidelines with expertise in traffic-related and behavioural psychology, and they use this as a basis for identifying and assessing risks and proposing appropriate mitigating measures. For this assignment, the following aspects were focused on: speed behaviour/credible speeds; safe design of verges and walls; light/dark transitions; the comprehensibility of information; and the complexity of the driving task. A key aspect of the tunnel is that there are only a few places where information about the junctions lying immediately beyond the tunnels can be displayed. Witteveen+Bos identified several risks that had not yet been considered.

The municipality accepted the recommendation of incorporating several of the proposed measures into the tunnel’s reconstruction project. These included applying a modified wall pattern on the retaining walls, aiming to reduce the clustering of signage, and installing extra shielding in the verges. Several measures will also be retained for future maintenance of the road lanes.

^{Image: Tom Feenstra}