Effect of traffic speed variations on safety of rural highways

Highway safety can be maximised by applying the highest geometric design standards. The highway geometric design standards of India are presently based on the design speed concept. However, due to constraints resulting from physical, right-of-way, and environmental features, uniform operating speed cannot be guaranteed. In order to make informed decisions to ensure highway safety, the combined effects of roadway design elements and traffic flow characteristics need to be studied. In the present paper, a continuous section of 56 km of State Highway-17 connecting Bangalore and Mysore in Karnataka, India, has been chosen. An attempt has been made to study the effect of variation of speed (speed change coefficient) between successive highway stretches on accidents at these stretches under mixed traffic flow conditions. The relationship between the speed change coefficient and change in the usable roadway width (width change coefficient) has also been investigated. Based on the study, it was observed that the number of accidents observed increased as the speed change coefficient deviates from a value of 1.00. Also, it was observed that the greater was the change in the width of usable roadway between successive road stretches, the greater was the speed change coefficient. For the covering abstract see ITRD E136183.