Modeling the Effect of Heavy Vehicles on Sign Occlusion at Multilane Highways

The research presented in this paper is concerned with modeling the occlusion of ground-mounted traffic signs by heavy vehicles on multilane highways. It is part of a more extensive research effort to examine the different factors that determine the effect of heavy vehicles on the visibility of traffic signs. An analytical tool was developed where road geometry, traffic sign, and moving entities are simulated over space at any point in time. This tool dynamically models the movement and location of passenger cars and trucks on the facility upstream of the subject traffic sign and verifies the continuity of sightline between the subject driver and traffic sign. Besides roadway and sign geometry, the model accounts for other traffic conditions such as traffic level, percentage of trucks, lane utilization, and average speeds of passenger cars and trucks. The occlusion of ground-mounted traffic signs by heavy vehicles is estimated using two measures. The first measure is the probability of a traffic sign being occluded by heavy vehicles under certain traffic and geometric conditions. The second measure estimates the likelihood of a passenger car driver missing the sign based on the minimum time required for the driver to detect, recognize, and read the message.