Many two-lane highways in rural areas experience operational problems related to high traffic volumes, lack of adequate passing opportunities; slow-moving vehicles on grades and in rolling terrain; roadside development that generates turning maneuvers at driveways; and, turning movements at intersections. The report evaluates five operational aids or treatments intended to alleviate these problems including: passing lanes, short four-lane sections, shoulder use sections, turnouts, and two-way left-turn lanes. The report reviews current signing, marking, and design practices used for these operational treatments in 13 States that participated in the study. The study concluded that each of the five types of operational treatments that were evaluated can be effective in improving traffic operations on two-lane highways. Passing lanes, short four-lane sections, and two-way left-turn lanes were also found to improve safety while turnouts and shoulder use sections were found to have no effect on safety.
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