Multilane highways are similar to freeways in most respects, except for a few key differences:

• Vehicles may enter or leave the roadway at at-grade intersections and driveways (multilane highways do not have full access control).

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• Multilane highways may or may not be divided (by a barrier or median separating opposing directions of flow), whereas freeways are always divided.

• Traffic signals may be present. • Design standards (such as design speeds) are sometimes lower than those

for freeways. • The visual setting and development along multilane highways are usually

more distracting to drivers than in the freeway case. Multilane highways usually have four or six lanes (both directions), have posted speed limits between 40 and 65 mi/h, and can have physical medians, medians that are two-way left-turn lanes (TWLTLs), or opposing directional volumes that may not be divided by a median at all. Two examples of multilane highway.


The determination of LOS on multilane highways closely mirrors the procedure for freeways. The main differences lie in the speed–flow relationship and some of the FFS adjustment factors and their values. The procedure we present is valid only for sections of highway that are not significantly influenced by large queue formations and dissipations resulting from traffic signals (this is generally taken as having traffic signals spaced 2.0 mi apart or more), do not have significant on-street parking, do not have bus stops with high usage, and do not have significant pedestrian activity.