PERCENT TIME-SPENT-FOLLOWING MODEL FOR SINGLE CARRIAGEWAY ROAD

Percent time-spent following (PTSF) is an important parameter in determining level-of-service of a single carriageway road but the current performance measure adopted in Malaysia is based on volume over capacity (v/c) ratio. Therefore, this study aims to develop a new PTSF model that is suitable for single carriageway roads in Malaysia. Traffic flow at 32 sites in various states in Malaysia were recorded using CCTV and video camera. Image processing software was used to extract volume, speed and headway data. Surrogate measure which is the percentage of vehicles travelling with headway threshold values of 3.0 and 5.0 seconds were used in estimating PTSF in the field. Initially, the base PTSF (BPTSF) model was developed and subsequently used to develop six different PTSF models using headway threshold values of 3.0 and 5.0 seconds and different variables. Analyses and performance indicators showed that the model developed based on the headway threshold value of 5.0 seconds with the inclusion of percentage of no-passing zone, opposing flow rate and percentage of heavy vehicles is the best model. This model was determined as the best fit as it has the highest score of 15, which is the maximum score based on performance indicator analysis.