Two Low-Cost Safety Concepts for Two-Way STOP-Controlled, Rural Intersections on High-Speed Two-Lane, Two-Way Roadways

The Federal Highway Administration (FHWA) Office of Safety has identified intersections as one of its safety focus areas. As part of the FHWA efforts to reduce intersection crashes and the related injuries and fatalities, two concepts have been identified: (1) rumble strips on outside shoulders and in a painted yellow median island on major road approaches and (2) channelizing separator islands on side road approaches with supplemental STOP signs. Specifically, the strategies are low-cost countermeasures for intersections at two-lane, two-way roadways with two-way STOP-control (TWSC). The lane narrowing concept (concept 1) features the introduction of rumble strips on the outside shoulders and in a painted yellow median island on the major road approaches.The objective of this first concept is to induce drivers on major roads to reduce approach speeds at intersections by effectively reducing the lane width. The minor road splitter island concept (concept 2) features channelizing separator islands on the side road approaches on which supplemental STOP signs are installed. The objective of the second concept is to provide redundancy of the STOP sign and increase driver-compliance with the STOP sign. A third concept includes the combination of concepts 1 and 2. The concepts have greater potential for effectiveness on intersections of high-speed roadways. However, they can also be applied to intersections with lower posted speed limits. With the cooperation of several transportation agencies, these two strategies were deployed at a limited number of sites in the United States. This paper documents an evaluation of the operational and safety effectiveness of these strategies. The general conclusion from this research is that positive operational and safety effects can be expected with the installation of concepts 1 and 2. The lane narrowing concept is shown to significantly reduce speeds on the major road approaches at rural, two-lane, TWSC intersections. The results are consistent across sites, which are combined in the main analysis. The minor road splitter island concept is shown to improve driver compliance as well as reduce speeds on the minor approaches at rural, two-lane, TWSC intersections. While the results for the minor road splitter island concept are based on just one site, the initial indications are promising. Based on the limited after period, there appears to be a general reduction in crashes associated with the implementation of concepts 1 and 2.