Analysis of Heavy Vehicle Induced Occlusion of Overhead and Sideway Signs

Traffic signs are used to convey critical information, such as directions, advisories, etc. to drivers however common experience indicates that there exist instances of missing a sign due to visual occlusion. Situation leading to missing a sign typically arise from an obstruction in the cone of vision of the driver because of the presence of a larger vehicle of it. The combination of distance headway, vehicle heights, vehicle speeds and sing characteristics, which may lead to occlusion, have been mathematically analyzed in this thesis. The analysis shows that if a traffic stream is operating in specific regions of a Cartesian apace than larger vehicles will occlude a sing from smaller vehicles following or adjacent to them. While studying such occlusion reading time of signs were also taken into account. Given the expected stream behavior on a road one can determine when vehicles will have trouble reading signs.