Samenvatting
The paper traces the development of the U.S. two- lane highway traffic capacity concepts and analysis methods from the original U.S. 1950 Highway Capacity Manual, through the 1965 Manual, to the 1985 version. The major difference in the 1985 version from its predecessors are the 2800 pc /h capacity value, the use of platooning as a level- of- service criterion, and the more realistic truck equivalencies for specific grades.Similar research developments in Australia are reviewed.