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The Effect of Highway Gradient on Passenger Car Equivalents (PCE) of Two-Lane Highways in Thailand

Bhawat Chaichannawatik 1, and Tassana Boonyoo 2
1. Department of Civil Engineering, Faculty of Engineering, Kasem Bundit University, Bangkok, Thailand
2. Traffic and Transport Development and Research Center (TDRC), King Mongkut’s University of Technology Thonburi, Bangkok, Thailand

Abstract— This paper is aimed to introduce the effect of highway gradient on Passenger Car Equivalent (PCE) values of the 13 types of vehicles on two-lane highways in Thailand. The study began with a literature review of PCEs, and then 12 sections of two-lane highway were intentionally selected and traffic data collected by using digital video cameras during 6:00 A.M. to 6:00 P.M. for two days for each site. After decoding video signals to identify traffic volumes, speeds, and time headways for all vehicle types. Next, the Lagging Time Headway (LTH) method was selected and applied to find the average 15-minute PCE values for every site. The analysis results showed that a highway gradient is a significant factor related to the PCE value. Moreover, the recommended PCE value of a two-lane highway under uninterrupted traffic flow according to the highway gradient was proposed in this study.
Index Terms— Highway gradient, Two-lane highway, Passenger car equivalent, Lagging time headway, Uninterrupted traffic

Cite: Bhawat Chaichannawatik, and Tassana Boonyoo, "The Effect of Highway Gradient on Passenger Car Equivalents (PCE) of Two-Lane Highways in Thailand," International Journal of Structural and Civil Engineering Research, Vol. 8, No. 4, pp. 333-339, November 2019. doi: 10.18178/ijscer.8.4.333-339