SPACING AND SPEED OF VEHICLES IN ROAD TUNNELS

The importance of appropriate driver behaviour in tunnels is emphasised. Safe distances between vehicles and speed limits should be displayed at the entrances to tunnels. The effect of vehicle spacing and speed on the capacity of a tunnel are described. Use of the chevron carriageway marking system to encourage correct vehicle spacing is considered. Traffic regulations for the tunnels in France are outlined. Justification of distances between vehicles in relation to smoke movement and the risk of fire spreading from vehicle to vehicle is described. Driver behaviour in tunnels usually fails to respect recommended vehicle spacings unless tunnels are divided into sections using traffic signal, light-emitting diodes or illuminated warning signs.