^ "Access Management Manual, Chapter 3 (Guidelines for Public Street and Driveway Connections), 3.4.6 (Restricted Movements and Median Openings)" (PDF).Utah Department of Administrative Services, Division of Administrative Rules. ^ "Title 930 (Transportation, Preconstruction), Rule R930-6-5 (Access Management, Definitions)".^ "Title 930 (Transportation, Preconstruction), Rule R930-6 (Access Management)" (PDF).RIRO configurations generally improve road-traffic safety and efficiency by reducing the number of conflict points between vehicles.Ī RIRO configuration may improve safety and operations at one intersection while consequently worsening them at another intersection upstream or downstream.
RIRO is especially useful where left turns would require crossing in front of oncoming vehicles. To travel in the restricted direction, vehicles must first turn in the permitted direction, then reverse direction in a U-turn, by going around a roundabout or by going left around a block. General types of RIRO road configuration include limited access roads ( divided highways, etc.) and roundabouts. RIRO road configurations are an important tool for access management. In the United States, they are sometimes called Jersey freeways, due to their prevalence in the state of New Jersey, although they are not limited to that state. Such roads are sometimes called RIRO expressways. RIRO roads may also have grade-separated interchanges, but vehicles on these roads do not yield the right-of-way to other vehicles entering the roadway, nor encounter cross traffic. The restriction may also be achieved by signage, but when a median or other barrier is not present in the median of the major road, RIRO configurations have been found to result in significant violation rates. The major road itself often has a median separating the two directions of traffic.
The RIRO restriction typically is enforced through physical barriers such as a traffic island in an intersection to direct vehicles into the permitted turn, and to restrict vehicles from traveling through the intersection. A study applying access management guidelines to the redesign of Missouri Route 763 in Columbia, Missouri illustrates how RIRO, combined with signalized intersections designed to permit U-turns, can accommodate high volumes of traffic with low delay and high safety.
RIRO is an important tool of access management, itself an important component of transportation planning.
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