Analysis of Drivers’ Compliance to Speed Limits Enforced with an Automated Section Speed Enforcement System

摘要

This study evaluated the effectiveness of speed limits enforced with an automated sectionspeed enforcement system (ASSES) through the analysis of compliance after the systemimplementation in the Italian Motorway A3 Naples-Salerno.The speed limits were selected taking into account take both the safety and themobility needs. The system was activated on April 21, 2010 and the driving speeds weremonitored in the two periods April 21, 2010 - May 11, 2010 and March 30, 2011 - April 20,2011. Non compliance to the speed limits was higher for the heavy vehicles (w>3.5 tons) thanfor the light vehicles (w≤3.5 tons). This is very challenging because of the high severity of thecrashes involving trucks, which is further increased by the higher speed. Non compliance ofthe light vehicles was much higher in the sections with the most constrained alignments(sections with speed limit 80 kph vs. sections with speed limit 100 kph, 65% vs. 40%). Anexplanation of this behaviour is that drivers do not adequately compensate for moredemanding driving conditions by reducing speed if the safe speed is much lower than thespeed desired in relation to the highway type and function. Overall, non compliance to thespeed limits was 50.5% in 2010 and 57.4% in 2011. The decrease in the drivers’ complianceover time suggests that a weak enforcement strategy was applied.Higher compliance to the speed limits, according to the authors’ belief, might beachieved by a better strategy of communication and information to the road users and a speedlimit management strategy synergic between the highway agency and the Police who actuallymanages the commitments of fines.