Modelling a car safety controller in road tunnels using hybrid petri nets

In the last years, major accidents have occurred in road tunnels with human losses (e.g. Mont Blanc, March ´99, St. Gotthard, Oct ´01 and Frejus, June ´05). The accidents have caused a large debate on how to increase road tunnel safety. One way to reduce risk is to minimize the undesired disturbances of the traffic flow by forcing vehicles to respect speed limits and safety distances. This paper investigates this specific issue and proposes a hybrid modeling approach based on fluid Petri nets (FPN). An FPN is used to represent a controller that keeps track of two consecutive vehicles, controls their speed and distance and issues alarms when the prescribed limits are violated. In the second part of the paper, it is shown that FPN is a valid paradigm to model the dynamics of a car in a detailed way