Michigan left
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Michigan_lefts.jpg
A Michigan left, sometimes known as a Michigan left turn or a Superstreet, is an automobile traffic maneuver in which a U-turn and a right turn replace a prohibited left turn. The term comes from the fact that the arrangement is quite common along Michigan roads and highways, and extremely rare anywhere else.
Michigan lefts occur at intersections where at least one road is a divided boulevard or highway. When left turns in the intersection are prohibited, drivers on major roads that cross the highway are instead directed to turn right. Within 1/4 mile, they go into a designated U-turn lane, and when traffic clears they complete the U-turn, and go back through the intersection.
Similarly, traffic on the highway does not turn left in the intersection. Instead, drivers overshoot the intersection, go into the U-turn lane, come back to the intersection and turn right.
The Michigan left was initially developed along Telegraph Road (U.S. Highway 24) and 8 Mile Road (Michigan State Highway 102) in Detroit in the 1960s, with over 700 similar intersections deployed throughout the state since then.
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Advantages
- Safety - eliminates many collisions in the intersection, although accidents may happen from cars leaving the U-turn and crossing several traffic lanes to turn right
- Reduces traffic light phases - increases green time for through traffic, and prevents backups in left-turn lanes (which can be replaced with backups in U-turn ramps and the lanes leading to them)
Disadvantages
- Stressful - drivers must quickly move across several lanes of traffic either when getting into or out of the U-turn, though separate traffic lights are sometimes provided at the U-turn ramps
- Safety - while eliminating collisions in the intersection, traffic has to join the opposing traffic flow at the U turn.
- Inconsistent - not all intersections use the system, so drivers approaching an unfamiliar intersection don't necessarily know whether to be in right or left lane, although signage is generally placed in advance of intersections requiring such a maneuver.
- Confusing - since the scheme is rare outside of Michigan, it is confusing to visitors, who expect to be able to turn left from the left lane
- Requires more land - if a new road is being designed, including Michigan lefts requires a wider median
- May require an additional traffic light to allow traffic a chance to exit the turnaround.
See also
External links
- The Michigan Left-Hand Turn (http://www.michiganhighways.org/indepth/michigan_left.html)
- North Carolina DOT - proposed "Superstreet" in Chapel Hill (http://www.ncdot.org/projects/Superstreet/optionc.html)