A volume warrant for the permitted phase of protected-permitted phasing

摘要

Protected plus permissive (P/P) phasing is currently used at approximately 29 percent of thernsignalized intersections in the United States. P/P phasing has a higher number of accidentsrncompared to protected-only, but is good for low to moderate traffic volumes. However, P/Prnphasing increases the efficiency of the intersection, so a tradeoff between safety and efficiencyrnwill be made if using this phasing. If safety is a primary concern, the use of P/P phasing shouldrnbe avoided. In this paper, we develop an analytic equation based on gap acceptance theory tornpredict the opposing volume at which the permitted phase of P/P phasing becomes ineffective. Inrnthe study intersections, the equation identified opposing volumes that were several hundredrnvehicles higher than the current rules of thumb. While additional intersections should be tested,rnpractitioners will find it a useful alternative to consider in making decisions regarding the use ofrnprotected plus permitted phasing.