A system and a method for determining the average time taken by vehicles to travel along road sections are described, in which a plurality of peripheral units (12, 14) distributed along a road network is used to detect the transit of vehicles by interrogating an on-board apparatus (B) of said vehicles, in particular an on-board apparatus designed for interfacing with land-based apparatus of an automatic toll collection system.
The peripheral units (12, 14) are connected to a central processing unit (20) which collects the data relating to the identification codes of the on-board apparatus (B) of the vehicles and the associated moments of transit past at least one pair of peripheral units (12, 14) and determines the average travel time of the section on the basis of the travel times of a plurality of vehicles detected passing by said peripheral units (12, 14).