Superstreet

For the air combat maneuver also known as the "J-turn", see Herbst maneuver. For the driving maneuver also known as the "J-turn", see J-turn.

This article reflects countries that drive on the right. For countries that drive on the left, reverse right and left.

At a superstreet, all traffic on the side road must turn right, where it can access a U-turn ramp. Traffic on the main road can turn left directly. The opposite applies for countries that drive on the left.

A superstreet, also known as a restricted crossing U-turn (RCUT), J-turn, or Reduced Conflict Intersection, is a type of road intersection that is a variation of the Michigan left. In this configuration, traffic on the minor road is not permitted to proceed straight across the major road or highway. Drivers wishing to turn left or go straight must turn right onto the major road, then, a short distance away, queue (wait) into a designated U-turn (or crossover) lane in the median. When traffic clears they complete the U-turn and then either go straight or make a right turn when they intersect the other half of the minor road.

This requires four traffic light-controlled intersections, and most traffic must pass through two of them, but each light has only two phases, greatly increasing average traffic flow; there is no need for numerous left-turn phases where most traffic is waiting for only a few cars to clear the intersection.

Practicality

Superstreets are not very common because they require substantial Right of Way to provide a median that can accommodate truck traffic. Inconvenience to traffic on the minor road is mostly a perception issue and does not represent additional delay in most cases. However, superstreets are cheaper than limited access freeways with interchanges and help traffic on the major road.

Usage

In North Carolina, five superstreet intersections were included as a part of U.S. Route 17's recent upgrades near Wilmington, North Carolina (). There are also three superstreet intersections in Holly Springs along the NC 55 bypass.

In Texas in 2010, several intersections on US 281 were converted to superstreet in the northern San Antonio neighborhood of Stone Oak, north of Loop 1604, to relieve rush hour congestion. In northwest San Antonio in 2011, two intersections on Loop 1604, north of State Highway 151, were converted to superstreet. In Austin, a superstreet is being phased in starting February 19, 2013, at the intersection of SH 71 and Farm to Market Road 973 east of Austin-Bergstrom International Airport not far from the eastern boundary of the Austin city limits. This becomes the city of Austin's first superstreet and the second city in Texas to feature this intersection design.

Troy, Michigan has a superstreet on West Big Beaver Road at Lakeview Drive.

Benefits

A study showed a 20 percent overall reduction in travel time compared to similar intersections that use conventional traffic designs; intersections experience an average of 46 percent fewer reported automobile collisions – and 63 percent fewer collisions that result in personal injury.

See also

• Michigan left
• Pittsburgh left

External links

• Federal Highway Administration, Alternative Intersection Treatments - Superstreet Median Crossover
• North Carolina DOT - proposed superstreet in Chapel Hill (note: this project does not include the left turns from the main road)
• Brunswick Beacon article Superstreet considered for U.S. 17
• Information on two superstreets in San Antonio, including detailed illustrations of the various traffic flows.
• FHWA: RCUT Case Study – Bypass 55 Corridor in Holly Springs (North Carolina), published July 31, 2014