The tunnel environment influences the hazards of road traffic in a specific way:
Hence in tunnels there is a trend towards less frequent, but (much) more severe incidents.
Tunnel safety studies typically focus on significant incidents, which have the potential to develop into events with serious consequences, mainly with collisions and fires. Furthermore, the manifold hazards potentially caused by dangerous goods require special attention. As an unrestricted availability of underground traffic infrastructure is crucial for economy as well as mobility, in particular on major transport axis and in areas with high traffic loads like big cities, events potentially causing significant traffic interruptions are additionally put into the center of attention. In this context security aspects have been gaining importance in the recent years.