Study of the literature on three-lane highways

The conflict in design principles arises particularly in the horizontal alignment and the vertical curved arc. The curved arcs frequently used in motorway design may create problems with overtaking visibility and therefore with road safety in general on single-lane highways. The guidelines specify a three-lane highway with alternating use of the central highway as one of the possible solutions to these conflicts. To gather information on three-lane highways a literature study was undertaken, of which the findings are presented in this report.