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(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
---|
0 | 100 | | Frontal and opposing direction sideswipe,Sideswipe | All | Principal Arterial Other Freeways and Expressways | Suburban |
0.98 | 2.05 | | Single vehicle | All | Principal Arterial Other Freeways and Expressways | Suburban |
0.36 | 63.64 | | Angle | All | Principal Arterial Other Freeways and Expressways | Suburban |
0 | 100 | | All | K | Principal Arterial Other | Rural |
0 | 100 | | All | A,B,C | Principal Arterial Other | Rural |
0 | 100 | | Angle | All | Principal Arterial Other | Rural |
0 | 100 | | Angle | All | Principal Arterial Other | Rural |
0 | 100 | | Angle | All | Principal Arterial Other | Rural |
0 | 100 | | Frontal and opposing direction sideswipe,Head on | All | Principal Arterial Other | Rural |
0.47 | 53.17 | | Single vehicle | All | Principal Arterial Other | Rural |
0.62 | 37.56 | | Rear end | All | Principal Arterial Other | Rural |
0.39 | 60.57 | | All | All | Principal Arterial Other Freeways and Expressways | Not specified |
0.85 | 15.5 | | All | K | Principal Arterial Other Freeways and Expressways | Not specified |
0.2 | 80.12 | | All | A,B,C | Principal Arterial Other Freeways and Expressways | Not specified |
0.63 | 36.63 | | All | O | Principal Arterial Other Freeways and Expressways | Not specified |
0 | 100 | | Angle | All | Principal Arterial Other Freeways and Expressways | Not specified |
0 | 100 | | Angle | All | Principal Arterial Other Freeways and Expressways | Not specified |
0 | 100 | | Angle | All | Principal Arterial Other Freeways and Expressways | Not specified |
0.63 | 36.63 | | Rear end | All | Principal Arterial Other Freeways and Expressways | Not specified |
1.41 | -40.83 | | Angle | All | Principal Arterial Other Freeways and Expressways | Not specified |
0.85 | 15.5 | | Frontal and opposing direction sideswipe,Sideswipe | All | Principal Arterial Other Freeways and Expressways | Not specified |
1.27 | -26.75 | | Angle | All | Principal Arterial Other Freeways and Expressways | Not specified |
0.85 | 15.5 | | Single vehicle | All | Principal Arterial Other Freeways and Expressways | Not specified |
1.67 | -66.67 | | Angle | All | Principal Arterial Other Freeways and Expressways | Not specified |
0.5 | 50.48 | | All | All | Principal Arterial Other | Not specified |
0 | 100 | | All | K | Principal Arterial Other Freeways and Expressways | Not specified |
0.81 | 18.97 | | All | A,B,C | Principal Arterial Other Freeways and Expressways | Not specified |
0.36 | 63.64 | | All | O | Principal Arterial Other Freeways and Expressways | Not specified |
0.08 | 92.12 | | Angle | All | Principal Arterial Other Freeways and Expressways | Not specified |
0 | 100 | | Angle | All | Principal Arterial Other Freeways and Expressways | Not specified |
0.32 | 68.49 | | Angle | All | Principal Arterial Other Freeways and Expressways | Not specified |
0.57 | 43.28 | | Angle | All | Principal Arterial Other Freeways and Expressways | Not specified |
0.95 | 5.46 | | Frontal and opposing direction sideswipe,Sideswipe | All | Principal Arterial Other Freeways and Expressways | Not specified |
1.42 | -41.81 | | Single vehicle | All | Principal Arterial Other Freeways and Expressways | Not specified |
0.91 | 9.09 | | Angle | All | Principal Arterial Other Freeways and Expressways | Not specified |
0.3 | 69.86 | | All | All | Principal Arterial Other Freeways and Expressways | Suburban |
0 | 100 | | All | K | Principal Arterial Other Freeways and Expressways | Suburban |
0.49 | 51.03 | | All | A,B,C | Principal Arterial Other Freeways and Expressways | Suburban |
0.28 | 72.02 | | All | O | Principal Arterial Other Freeways and Expressways | Suburban |
0 | 100 | | Angle | All | Principal Arterial Other Freeways and Expressways | Suburban |
0 | 100 | | Angle | All | Principal Arterial Other Freeways and Expressways | Suburban |
0 | 100 | | Angle | All | Principal Arterial Other Freeways and Expressways | Suburban |
1.96 | -95.89 | | Angle | All | Principal Arterial Other Freeways and Expressways | Suburban |