In the field ofroad transport, aturnaround is a type ofjunction that allows traffic traveling in one direction on a road to efficiently make aU-turn (to reverse course and travel the opposite direction) typically without backing up or making dangerous maneuvers in the middle of the traffic stream. While many junction types permit U-turns, the termturnaround often applies to road junctions built specifically for this purpose.
The following road junction types are designed specifically to allow U-turns.
TheTexas U-turn allows traffic traveling on one direction of a one-wayfrontage road, running parallel to a highway, to cross the highway (via agrade separation) and turn onto the other frontage road, traveling in the opposite direction. The term refers to roadworks which are specially built for this purpose; it does not refer to use of an intersecting roadway to navigate between frontage roads.[1]
A junction resembling a "backwardjughandle" is sometimes found, allowing U-turns. According to the U.S.Federal Highway Administration, this is actually just a variant of a standard median U-turn crossover, built to accommodate roads with medians too narrow to otherwise permit a U-turn to be made safely.[2] Traffic wishing to turn around executes a turn across oncoming traffic (left in countries where trafficdrives on the right; right in countries where traffic drives on the left) onto the at-grade ramp (sometimes called a "bulb out" or a "loon"),[3][4] but rather than merging onto a crossing road, the "bulb out" turns back and merges onto the road the traffic just left, in the opposite direction.
Examples on a controlled-access highway withfrontage roads are on the Manuel Gómez Morín Beltway, just north and south of Mariano Otero Avenue inZapopan, Mexico, just outsideGuadalajara.[11][12][13][14] Here, traffic travels to a frontage road, whose inner (left) lane leads to a U-turn ramp which descends and forms an underpass below the beltway; traffic then ascends and joins the inner (left) lane of the opposing frontage road.
Other examples on a controlled-access highway are on theDamansara–Puchong (E11) Expressway (also known by itsMalaysianacronym, LDP), between exit 1114 (the Puchong Jaya Interchange) and exit 1118 (the Puchong Intan Interchange), inPuchong, Malaysia, nearKuala Lumpur.[15] Traffic drives on the left, and the outer (left) lanes serve as hybrid entrance or exit lanes and frontage roads. In each direction, outer-lane traffic can travel to a U-turn ramp which forms anoverpass above the LDP. The U-turn ramps come close to each other, but remain separate; no roadway surface is shared by opposing traffic.
An example on anundivided highway is on theSanibel Causeway, connectingSanibel Island with the mainland in South Fort Myers,Florida, United States.[16][17] Traffic traveling toward the mainland can exit onto a U-turn underpass, then return on the causeway to Sanibel Island.
In some countries, acul-de-sac allows a smooth turnaround at the end of a dead end street.
The following junction types typically permit U-turns but are not designed specifically for that purpose.
Normalat-gradeintersections on divided highways often allow traffic traveling on the divided highway to perform a U-turn, often when there is a green light for traffic turning onto the side road, crossing the opposing lanes (left turns in countries where trafficdrives on the right; right turns in countries where traffic drives on the left).
Traffic at at-grade intersections withjughandles can usually use the jughandle ramps and side roads to turn back onto the original road in the opposite direction.
Many freewayinterchanges withsurface streets are configured so that traffic on the freeway can exit onto the surface street, and re-enter the freeway in the opposite direction.
Thecloverleaf interchange permits turning around by navigating two consecutive "leaves" of the clover pattern.
On 8 de Julio Avenue, just north of the Manuel Gómez Morín Beltway inTlaquepaque, Mexico, just outsideGuadalajara, there is a U-turn junction formed from two other types of junctions.[18][19] First, traffic wanting to turn around travels onto what theNew Jersey Department of Transportation in the United States defines as a "Type B"jughandle (one used where there is no cross street, allowing a U-turn or a turn onto a side street).[20] Then, U-turning traffic crosses the road and travels along a narrow median variant of a median U-turn crossover, completing the turn. The entire junction resembles a grade-separated turnaround ramp as described above, except this one is at-grade.
Some so-calledright-in/right-out expressways,left-in/left-out expressways andJersey freeways have overpass or underpass roads which connect to side roads accessed byright-in/right-out or left-in/left-out turns from the highway. While not strictly junctions, these road configurations serve a turnaround function analogous to freeway interchanges with surface streets, as described above. They can also be used by traffic entering the highway farther back which lacks a turnaround of its own.
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