Study Details

Study Title: The J-Turn Intersection: Design Guidance & Safety Experience

Authors: Hochstein et al.

Publication Date:JAN, 2009

Abstract: A rural expressway is a high-speed, multi-lane, divided highway with partial access control. It is typically divided by a wide, depressed median and consists of both at-grade intersections and grade separated interchanges. Converting undivided rural two-lane highways into expressways is a popular highway safety improvement as expressways make passing easier and drastically reduce the likelihood of head-on and opposite direction sideswipe collisions. However, at-grade intersection collisions on rural expressways are reducing the safety benefits that should be achieved through conversion. The underlying problem seems to be that expressway intersections present challenges to crossing and left-turning minor road drivers attempting to select gaps in the far-side expressway traffic stream. State Transportation Agencies (STAs) have experimented with several intersection safety treatments at problematic two-way stop controlled (TWSC) rural expressway intersections to improve their safety performance while trying to avoid signalization or grade separation. One of these treatments is the J-turn intersection design. This paper describes the J-turn intersection design concept, examines existing design guidance, and documents the experience of the Maryland State Highway Administration and the North Carolina Department of Transportation with this innovative intersection design. The assumed safety benefit of J-turn intersections isthat they reduce the potential for right-angle collisions (particularly far-side right-angle collisions) by replacing direct crossing and left-turn maneuvers from the minor roads at TWSC expressway intersections with right-turns and downstream U-turns. Naïve before-after crash data comparisons conducted at four sites reveal that this intersection design concept can offer superior safety performance as compared to a typical TWSC rural expressway intersection.

Study Citation: Hochstein, J., T. Maze, T. Welch, H. Preston, and R. Storm, "The J-Turn Intersection: Design Guidance & Safety Experience." TRB 88th Annual Meeting Compendium of Papers CD-ROM. Washington, D.C., (2009).


CMFs Associated With This Study

Category: Intersection geometry

Countermeasure: Install J-Turn intersection

CMF CRF(%)QualityCrash TypeCrash SeverityRoadway TypeArea Type
01001 StarFrontal and opposing direction sideswipe,SideswipeAllPrincipal Arterial Other Freeways and ExpresswaysSuburban
0.982.051 StarSingle vehicleAllPrincipal Arterial Other Freeways and ExpresswaysSuburban
0.3663.641 StarAngleAllPrincipal Arterial Other Freeways and ExpresswaysSuburban
0.0892.431 StarAllAllPrincipal Arterial OtherRural
01001 StarAllKPrincipal Arterial OtherRural
01001 StarAllA,B,CPrincipal Arterial OtherRural
0.2575.021 StarAllOPrincipal Arterial OtherRural
01001 StarAngleAllPrincipal Arterial OtherRural
01001 StarAngleAllPrincipal Arterial OtherRural
01001 StarAngleAllPrincipal Arterial OtherRural
01001 StarFrontal and opposing direction sideswipe,Head onAllPrincipal Arterial OtherRural
0.4753.171 StarSingle vehicleAllPrincipal Arterial OtherRural
0.6237.561 StarRear endAllPrincipal Arterial OtherRural
0.3960.571 StarAllAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.8515.51 StarAllKPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.280.121 StarAllA,B,CPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.6336.631 StarAllOPrincipal Arterial Other Freeways and ExpresswaysNot specified
01001 StarAngleAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
01001 StarAngleAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
01001 StarAngleAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.6336.631 StarRear endAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
1.41-40.831 StarAngleAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.8515.51 StarFrontal and opposing direction sideswipe,SideswipeAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
1.27-26.751 StarAngleAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.8515.51 StarSingle vehicleAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
1.67-66.671 StarAngleAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.550.481 StarAllAllPrincipal Arterial OtherNot specified
01001 StarAllKPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.8118.971 StarAllA,B,CPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.3663.641 StarAllOPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.0892.121 StarAngleAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
01001 StarAngleAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.3268.491 StarAngleAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.5743.281 StarAngleAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.955.461 StarFrontal and opposing direction sideswipe,SideswipeAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
1.42-41.811 StarSingle vehicleAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.919.091 StarAngleAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.369.861 StarAllAllPrincipal Arterial Other Freeways and ExpresswaysSuburban
01001 StarAllKPrincipal Arterial Other Freeways and ExpresswaysSuburban
0.4951.031 StarAllA,B,CPrincipal Arterial Other Freeways and ExpresswaysSuburban
0.2872.021 StarAllOPrincipal Arterial Other Freeways and ExpresswaysSuburban
01001 StarAngleAllPrincipal Arterial Other Freeways and ExpresswaysSuburban
01001 StarAngleAllPrincipal Arterial Other Freeways and ExpresswaysSuburban
01001 StarAngleAllPrincipal Arterial Other Freeways and ExpresswaysSuburban
1.96-95.891 StarAngleAllPrincipal Arterial Other Freeways and ExpresswaysSuburban