Citation

Chang J, Oh C, Chang M. Transp. Res. Circular 2000; (E-C018): 200-208.

Copyright

(Copyright © 2000, U.S. National Academy of Sciences Transportation Research Board)

DOI

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PMID

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Abstract

The objective of this study is to clarify the relationship between volume to capacity ratios (v/c) and accident rates at various freeway facility sections. These relationships can be used as a basic reference to predict and prevent traffic accidents. The traffic volume and the number of accidents from 1992 to 1997 on Shingal-Ansan freeway in Korea were analyzed in this study. The hourly accident rate and hourly v/c were calculated for each freeway section: the basic freeway section, tunnel section, and toll gate section. The accident rate models, having an independent variable of v/c, were established by regression analysis and compared with each other. The relationship between accident rates and v/c ratios represented a U-shaped pattern for all sections. The accident rates are highest in the low hourly v/c range, decrease with an increasing v/c ratio, and then increase as the v/c ratio increases. The accident rate of the toll gate section is generally higher than that of other sections. Although the accident rate of the tunnel section is higher than that of the basic freeway section when the v/c is above 0.67, there is no significant difference in accident rates between the basic freeway and tunnel sections when the v/c is between 0.5 and 0.8. The basic freeway, tunnel, and toll gate sections have the minimum accident rates when the v/c is 0.78, 0.75, and 0.57, respectively.