MS DOT Synthesis of J-Turn Design Standards and Criteria

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Abstract:

Transportation professionals today are faced with the challenge to meet the mobility needs of an ever increasing population with limited resources. One potential treatment to mitigate congestion and safety problems at rural expressway intersections, while trying to avoid signalization or grade‐separation, is the J‐Turn intersection treatment, which has been successfully implemented in Michigan, Florida, Maryland, New Jersey, and Louisiana.

The treatment involves the prohibition of left‐turn and through movements from the side‐street approaches and accommodates them by requiring drivers to turn right onto the main road and then make a u‐turn maneuver at a one‐way directional median opening downstream. Left‐turns from the main road approaches are executed in a manner similar to left‐turns at a conventional intersection and are unaffected. Although this type of intersection treatment is typically considered a corridor‐wide treatment, the concept has been successfully used at isolated intersections to improve traffic flow and enhance safety.

This synthesis presents design guideline recommendations for the implementation of J‐Turn intersection treatments in Mississippi. Specific items addressed in this document include general design elements, cross-sectional elements, intersection and crossover design details, pedestrian accommodations, traffic control devices, lighting, signing, historical safety performance, construction costs and phasing, and public involvement efforts. The recommendations herein should be considered as minimums. The recommendations contained in this document cannot apply to all situations as every project is unique and typically require their own variations to site‐specific conditions.

Many of the design elements recommended for the J‐Turn intersection and MUT crossovers match the current MDOT practices for arterials. All references contained in this document refer to the 2001 edition of the MDOT Roadway Design Manual, which is currently undergoing a major revision. Therefore, the designer should verify that the most recent design criteria is being used prior to beginning a design.  

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