Effect of Pavement Condition on Multilane Highway Free Flow Speed

Multilane highways are highways with two or more lanes in each direction that are either undivided or divided by medians or two-way left turn lanes. Free flow speed (FFS) was adjusted to a non-ideal road condition in the Highway Capacity Manual (HCM) from the early 1990s. The HCM methodology for multilane highway level of service (LOS) analysis depends mainly on the FFS estimation.