Effects of Inadequate Driveway Corner Clearances on Traffic Operations,Safety,and Capacity

Inadequate driveway corner clearances can result in traffic operational, safety, and capacity problems. These problems can be caused by blocked driveway ingress and egress movements, incomplete turning maneuvers, conflicting intersection turning movements, confusing right-turn signal indications, insufficient weaving and merging section lengths, and various other conflicts. The effects of driveway corner clearances on safety cannot be examined easily through safety records given the current condition of the available crash and system inventory data. This provides incentives for applying theoretical traffic conflict analysis. A simple conflict analysis showed an increase in merging and crossing conflict points for driveways situated near intersections. Inadequate corner clearance can have a capacity-reducing effect. Driveway capacity may be reduced by (a) vehicles on the arterial blocking driveway egress movements and (b) a decreased opportunity for left-turn egress movement on arterial streets designed for platoon progression. Intersection capacity can also be reduced by a decrease in saturation flow rates due to driveway ingress and egress movements.