Citation

Trout RS, Loutzenheiser RC. Transp. Res. Rec. 1976; 615: 28-29.

Copyright

(Copyright © 1976, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

This comparative study made paired observations of service level calcualtions by the critical movement summation (CMS) and the Highway Capacity Manual (HCM) methods, at selected at-grade intersections, to determine the similarity of the service levels. The HCM method and the CMS method produced different results for intersection analyses as indicated by the Wilcoxon statistical test. The service levels calculated by the HCM method for intersections are usually inferior to those calculated by the CMS method. The service levels calculated by the HCM and CMS methods appear to be closer when the intersection is signalized and flowing at levels E (1451 to 1600 vehicles/h) or F (greater than 160). A questionnaire survey revealed that the majority of respondents used the HCM method or related charts for at-grade service level determination; the sampling techniques used by most respondents for determining various HCM factors were single sample and judgement; exposure to the CMS method is very limited and exists primarily in the eastern U.S.; and those who use CMS method judge it easy to use and to communicate.