THE MARGINAL DECREASE OF LANE CAPACITY WITH THE NUMBER OF LANES ON HIGHWAY

This paper attempts to investigate the impact of the number of lanes on highway capacity. Methodologically, we provide a better understanding of the relationship between highway capacity and its number of lanes upon the statistical analysis of the survey. We employ the variance analysis of single factor for modeling the effect of the number of lanes on capacity. The findings show that average capacity per lane decreases with increasing number of lanes on uninterrupted highway segments. The analysis is based on an extensive field survey of traffic flow in Beijing. The implication of the marginal decrease of lane capacity requires that the manuals of highway capacity should be revised for the better plan and design of road network. In addition, the factor of marginal decrease should be incorporated into the decision on adding lanes or constructing a new parallel road when travel demand exceeds road capacity.