Investigating the effects of access road intersections on freeway congestion

The research involved the development of a model to identify exit ramps for their severe congestion conditions due to the location of access road intersections. The storage space between the points at which the exit ramp merges with the access road and the stop line at the downstream intersection is expressed in terms of number of vehicles it can accommodate and is compared with the total number of vehicles retained per signal cycle. The exit ramp volume, through traffic volume, number of lanes approaching the intersection, cycle length and green time at the signalized intersection during a peak hour are the parameters used. The model concludes that a particular exit is problematic if the storage space is not adequate to store the vehicles approaching the intersection in one cycle thereby leading to traffic congestion. Geometric and signal timing modifications are recommended accordingly.