An investigation of the 85th percentile operating speed models on horizontal and vertical alignments for two-lane rural highways: A case study

Abstract

The number of accidents in Malaysia increases relatively from year to year, although there are many programmes organised by the authority to reduce them. There are several factors that lead to serious accident problems which are human behaviour, vehicle’s condition, weather condition, road surface and road alignments (vertical and horizontal curves). This research paper presents an empirical research and presents design consistency models to estimate the 85th percentile operating speed models for the horizontal and vertical alignments at two-lane rural highways. The speed data were carried out by using a laser gun metre detector to obtain the spot speed data in the selected location along the Lenggong to Sauk two-lane rural highway in Perak. Multiple linear regression analysis was conducted to develop the 85th percentile speed models by combining the operating speed data and geometric elements data from different selected horizontal and vertical alignments. Finally, the horizontal and vertical alignment models have successfully developed in the paper. The findings are hoped to provide a starting point towards the national design standard for the highway designer and planner to improving the consistency geometric design elements of the two-lane rural highways