Adapting V-ISA Technology: Driver Behaviour along Interchange Ramp and Merging/Diverging Terminals

An original in-vehicle Intelligent Speed Adaptation System for Visibility (V-ISA) was designed to promote compliance with real-time speed management. The functionality of V-ISA is based on the prevailing sight conditions along the road, and operates in two variants: (i) providing visual information, and (ii) vehicle speed intervention. A road scenario with the driver performing merging and diverging manoeuvres in a motorway section was designed. A within-subject experiment involved 32 participants and a vehicle equipped with the two variants and the system off (baseline condition) under two traffic flow conditions. V-ISA had a significant positive effect on the drivers' longitudinal performance along ramps. This change in behaviour along ramps had no effect on merging and diverging manoeuvres. V-ISA had a positive impact on driver speed behaviour in such complex road environment and assisted drivers to modulate the operating speed towards the safe dynamic limits.