Improved Analysis of Two-Lane Highway Capacity and Operational Performance

The objective of this research is to (1) identify appropriate performance measures for operational and capacity analyses of two-lane highways and develop models to produce these performance measures in an Highway Capacity Manual (HCM) context, and (2) develop or modify a simulation-based analysis method for two-lane highways and offer guidance for when to apply a simulation versus HCM methods.

Two-lane highways account for a very significant portion of the national highway system and serve an essential function for the movement of people and goods. As urban areas continue to see growth further away from the central cities, two-lane highways in previously less developed areas are experiencing increases in traffic demand. Although adding additional lanes to a two-lane highway will often address operational deficiencies with two-lane highways, such construction projects are very expensive. Having good and accurate analysis methods for two-lane highways may allow roadway design and traffic engineers to identify ways to make significant improvements to the operational performance of a two-lane highway without resorting to a full multilane configuration.  The standard reference in the U.S. for traffic analysis techniques is the Highway Capacity Manual (HCM). The HCM 2010 contains a chapter that provides an analysis methodology for twolane highways. Unfortunately, the HCM analysis procedure falls short in several respects of providing roadway design and traffic engineers the methods they need for performing accurate and comprehensive two-lane highway facility evaluations.   The objective of this research is to (1) identify appropriate performance measures for operational and capacity analyses of two-lane highways and develop models to produce these performance measures in an Highway Capacity Manual (HCM) context, and (2) develop or modify a simulation-based analysis method for two-lane highways and offer guidance for when to apply a simulation versus HCM methods. The resulting methods will lead to a two-lane highway facilities procedure suitable for incorporation into a future edition of the HCM.