Asuperstreet[a] is a type ofroad intersection that is a variation of theMichigan left. In this configuration, in contrast to the Michigan left, traffic on the minor road is not permitted to proceed straight across the major road or highway. Drivers on the minor road wishing to turn left or go straight must turn right onto the major road, then, a short distance away, queue (wait) into a designatedU-turn (or crossover) lane in themedian. When traffic clears, they complete theU-turn and then either go straight or make a right turn when they intersect the other half of the minor road.
The superstreet typically requires fourtraffic 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. Turning movements on roads with lower cross-traffic volumes may be controlled withstop oryield signs for turning traffic rather than with signals.
A (standard) RCUT, in contrast to a Michigan left, typically allows left turns from the major road to minor roads. A variation, designated by the USFederal Highway Administration (FHWA) as abasic RCUT, prohibits such turns, restricting movements toright-in/right-outs and medianU-turns only.) When the median is relatively narrow, a "bulb-out" or "loon" protrudes from the roadway, opposite from the median crossover, to accommodate a U-turn by a long vehicle, such as atractor trailer.[3]
Superstreets are not very common because they require substantialright-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.[citation needed] However, superstreets are cheaper to construct thancontrolled-access highways and improve the flow of traffic on the major road.
InPort St. Lucie, Florida, the first superstreet in Florida was opened in late 2019 at the intersection of Crosstown Parkway and Floresta Drive.[4]
In May 2015, a superstreet was constructed onUS 41 atSR 114 on the border betweenMorocco andBeaver Township inNewton County, Indiana. The state of Indiana makes a distinction between an RCUT, which it defines as having a traffic light-controlled main intersection, and a J-turn or RCI, which it defines as having the main intersection controlled by stop or yield signs.[5] Two examples of what Indiana calls a "J-turn" opened on June 30, 2016 at the intersections ofUS 231 withIN 62 andIN 68 nearDale. Traffic on the state roads at both intersections can only turn right, while US 231 traffic can turn left at both intersections.[6]
Troy, Michigan has a superstreet on West Big Beaver Road at Lakeview Drive (42°33′41″N83°10′53″W / 42.561383°N 83.181310°W /42.561383; -83.181310). A simpler implementation is seen inWashington Township, Macomb County, Michigan at M-53 and 30 Mile Road (42°46′21″N83°00′33″W / 42.7726°N 83.0091°W /42.7726; -83.0091).[citation needed]
Cadiz, Kentucky has a superstreet at the intersection of US 68 and Highway 139 ( 36°50'37.97"N, 87°49'30.61"W).[7]
Lake Elmo, Minnesota has a superstreet intersection onMN 36 at Keats Avenue (45°02′08″N92°54′14″W / 45.0356°N 92.9038°W /45.0356; -92.9038).[citation needed]
InNorth Carolina, five superstreet intersections were included as a part ofU.S. Route 17's recent upgrades nearWilmington, North Carolina (34°12′58″N78°01′08″W / 34.21603°N 78.018969°W /34.21603; -78.018969).[citation needed][when?] There are also five superstreet intersections inHolly Springs along theNC 55 bypass.[8]US221 from the South Carolina stateline north to the US74 interchange is of superstreet construction
In 2011,Ohio State Route 4 Bypass inButler County, Ohio, was reconfigured with three superstreet intersections.[9] TheOhio Department of Transportation (ODOT) is also planning to build a superstreet onUS 127 at Kruckeberg Road inGreenville Township, Darke County beginning in summer 2019. ODOT materials make a distinction between the project's standard RCUT design, which ODOT terms a "partial RCUT", and what the FHWA calls a "basic RCUT", which ODOT terms an "RCUT" or a "full RCUT".[10][11]
InTexas in 2010, several intersections onUS 281 were converted to superstreet in the northernSan Antonio neighborhood ofStone Oak, north ofLoop 1604, to relieve rush hour congestion.[12][13][14] This superstreet was removed in 2019 following the start of construction to convert US 281 into a full freeway. In northwest San Antonio in 2011, two intersections on Loop 1604, north ofState Highway 151, were converted to superstreet.[15][16] These intersections, however, were also removed when 1604 was upgraded to freeway status in the area. InAustin, a superstreet was built on February 19, 2013, at the intersection ofSH 71 andFarm to Market Road 973 east ofAustin-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.[17] This superstreet was removed in 2019[18] following the construction of the SH 71 Toll Lane. Another superstreet exists in Austin onLoop 360 between the intersections ofLoop 1 andUS 290 which provides access to Barton Creek Plaza. This superstreet allows southbound traffic on Loop 360 to travel from Loop 1 to US 290 without going through any traffic lights. Three new superstreet intersections are being constructed in College Station along FM 2818 (Harvey Mitchell Parkway) at FM 2347 (George Bush Drive), Luther Street, and Holleman Drive.[19]
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.[20]
This design also is promoted as part of the FHWA'sEvery Day Counts initiative which started in 2011.[21]