EFFECT OF SHOULDER CONDITION ON HIGHWAY CAPACITY AND TRAFFIC OPERATION

Abstract

Shoulder is an important element of a highway system. Well designed and properly maintained shoulders are essential for safe and smooth traffic operation. Shoulders are necessary on rural highways with any appreciable volume of traffic. However, shoulders are one to the most neglected elements of roadway and are very poorly maintained in India. Shoulders play a very important role in the full development of the capacity of the road because they create a feeling of openness to the drivers and allow both passing and overtaking manoeuvers of vehicles safely and conveniently which are most difficult on single lane road. In the present study, the placement of vehicles form the pavement edge has been taken as the governing factor to determine the effect on roadways capacity. Assuming, that the vehicles would make use of full width of pavement if good type of shoulders are provided on either side of the road. Data was collected on different section of SH-45, SH-12, MDR-121W and MDR-131W, where shoulders were in a bad shape or not provided at all. It was found that the poor maintenance of shoulders results in loss in effective width of carriageway for traffic movement. It varies from 10 to 20% depending upon the total width of the carriageway. The speed of a vehicle was considerably reduced during crossing manoeuver on sections where shoulders were either completely damaged or not properly maintained during overlaying. The speed of heavy vehicle was found to have reduced form 57.3 Kmph to 46.3 Kmph on a 6.5 m wide road. On a single lane road, speed reduction was as high as 52.8%.