Evaluation of the Highway Capacity Manual (HCM) and Thailand’s Department of Highways’ approaches to estimating the capacity of a multilane highway segment via the empirical method
Issued Date
2024-10-09
Resource Type
ISSN
25396161
eISSN
25396218
Scopus ID
2-s2.0-85212771723
Journal Title
Engineering and Applied Science Research
Volume
51
Issue
6
Start Page
747
End Page
755
Rights Holder(s)
SCOPUS
Bibliographic Citation
Engineering and Applied Science Research Vol.51 No.6 (2024) , 747-755
Suggested Citation
Srisurin P., Amprayn C. Evaluation of the Highway Capacity Manual (HCM) and Thailand’s Department of Highways’ approaches to estimating the capacity of a multilane highway segment via the empirical method. Engineering and Applied Science Research Vol.51 No.6 (2024) , 747-755. 755. doi:10.14456/easr.2024.70 Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/102546
Title
Evaluation of the Highway Capacity Manual (HCM) and Thailand’s Department of Highways’ approaches to estimating the capacity of a multilane highway segment via the empirical method
Author(s)
Author's Affiliation
Corresponding Author(s)
Other Contributor(s)
Abstract
This study aims to evaluate the methods used by the Thailand Department of Highways (DOH) and the Highway Capacity Manual (HCM 2010 and HCM 2016) for estimating the capacity of an urban multilane highway segment in Thailand, by comparing these estimates with the empirical capacity derived from a speed-flow plot. Field data were collected from a six-lane urban highway segment in Thailand, followed by documentation of the roadway conditions and analysis of vehicle composition. Capacity estimates were calculated using the DOH and HCM methods prior to comparing them to the empirically measured capacity. The results showed that the empirical capacity was 1,619 pc/h/ln. The capacities estimated using the HCM 2010 and HCM 2016 methods were 34.8% and 35.3% greater than the empirically measured capacity, respectively, while the capacity estimated using the DOH method was 14.1% lower than the measured capacity. These findings indicate significant discrepancies in the estimates produced by the three models, when applied to the multilane highways segment. Given that the DOH model has not been updated in over two decades, this study concludes that its accuracy in capacity estimation may be compromised by evolving factors, such as driver behavior, traffic flow characteristics, vehicle types, and vehicle performance. Moreover, the DOH method's omission of variables (including access point density, median type, and terrain type) may further affect its accuracy. Similarly, since HCM 2010 and HCM 2016 are tailored to the United States, using both models to estimate the capacity of the multilane highway segment of interest may lead to errors due to differences in driver behaviors between Thai and American drivers, distinct traffic flow characteristics, the model’s omission of the percentage of motorcycles, and the overestimation of speed at capacity on the highway segment.