The future Westerschelde tunnel will consist of two separated tunnel tubes of 6.6 km in length, one for each direction. The cross-section of each tube is just wide enough to contain two lanes of 3.5 meters wide. Due to financial constraints a separate tube for pedestrians will not be built and the cross-section of the tube does not allow any room for a separated pavement along the side of the road. Therefore, the tubes will be connected by transverse links at intervals of 250 meters. In an emergency situation the doors to the transverse links will be unbolted to allow people to escape to the safe tube. Conflicts between moving traffic and escaping car drivers can result in another unsafe situation. A study was carried out in order to find a way to minimise this safety deficit. In case of a required evacuation, safety measures should also be activated in the 'safe' tube as soon as possible in order to expel traffic from the left lane or even stop the traffic completely. This must be achieved in a save manner for all road users. To analyse safety during evacuations, a study was conducted in three work packages, namely a literature review, a workshop with experts on traffic signalling and evacuation in tunnels, and a driving simulator study. Based on these studies, it can be concluded that moving all the traffic to the right driving lane is preferred over stopping all the traffic in the tunnel tube. Introducing this measure in a rather gradual or a more abrupt manner did not result in too many differences. However, a more gradual introduction (by means of a white arrow before using a red cross) is more in correspondence with current experience. Therefore, this strategy is to be preferred. Using a variable message sign with an indication of a running pedestrian is to be recommended, since this way road users are better prepared for the presence of pedestrians in the tunnel. The results from the questionnaires indicated that in general, subjects understand what kind of behaviour is required. The chances of panic in the unsafe tube are rather small. Especially when road users are informed adequately, they are expected to act calmly. (Author/publisher)
Samenvatting