Study the Effect of Guide Sign Position on Traffic Behavior at Exit Freeway Weaving Areas by Developing Computer Simulation Program (FWASIM)

Abstract

Traffic control devices notify road users of regulations and provide warning andguidance needed for safe, uniform, and efficient operation of all elements of the trafficstream. Traffic control devices have been a part of the roadway system. Researcheshave evaluated various aspects of the design, operation, placement, and maintenanceof traffic control devices.The purpose of this research is to develop a simulation model in order toevaluate the effect of overhead sign position on the traffic performance at exit offreeway weaving area. To achieve that subroutine was developed and added toFWASIM program to compute the sign position and compare it with the driver sightdistance. Following that a proposed example represents an exit weaving area wasexamined with different traffic flow configuration (different percentages of link flowand on-ramp flow) with respect to no sign installed and other three sign positions.Results indicate that the average traffic speed is underestimated when there is no signinstalled, while no significant effect is shown when the sign position is changed withinthe driver sight distance.In conclusion Guide signing is a critical element in the effective, efficient andsafe operation of motorways and expressways. Signing issues must, therefore, be fullyconsidered at the feasibility stage of any project.