Michigan Left
Encyclopedia : M : MI : MIC : Michigan Left
A Michigan left, sometimes known as a median U-turn, is an automobile traffic maneuver in which a unidirectional 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 in the United States.
Description
Michigan lefts occur at intersections where at least one road is a divided highway or boulevard. Left turns onto the divided highway are prohibited. Instead, drivers on roads that cross the highway are directed to turn right. Within a 1/4 mile (400 m), they queue into a designated U-turn lane in the median. When traffic clears they complete the U-turn and go back through the intersection. For additional safety purposes, the U-turn lane is designed so traffic only flows through it one-way.Similarly, traffic on the divided highway cannot turn left at an intersection with a cross street. Instead, drivers are instructed to overshoot the intersection, go through the U-turn lane, come back to the intersection from the opposite direction and turn right.
Locations
The Michigan left was initially piloted by MDOT at the intersection of 8 Mile Road (M-102) and Livernois Avenue[(map)] in Detroit in the early 1960s. The increase in traffic flow and reduction in accidents was so dramatic that over 700 similar intersections have been deployed throughout the state since then.
The Michigan left is also common in New Orleans, Louisiana[[Citing sources citation needed]], in South Korea[[Citing sources citation needed]], and in Taiwan[[Citing sources citation needed]].
Pros and cons
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
- Traffic flow — Reduces the number of different traffic light phases. Since separate phases are no longer needed for left-turns, this 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)
- More options for turning — At intersections where both roads have Michigan Lefts, there is more than one way to turn left. For example it is possible to either turn right at the intersecting road, and use the U-turn to go left, or go past the intersecting road, use the U-turn on the original road, and make a right on the intersecting road. This is very useful when trying to avoid traffic lights provided there isn't a "No turn on red" sign. It also allows for an alternate path in case of a traffic-blocking incident.
- Cost — U-turn lanes are often already present on divided highways to provide for access to businesses in the opposing direction. Hence the addition of the Michigan left turnaround is essentially free.
Disadvantages
- 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.
- 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.
- Land Use – Michigan lefts are only practical on roads with wide medians.
- Stress – drivers must quickly move across several lanes of traffic when getting into or out of the U-turn, although if traffic does not permit, typically another U-turn is available within less than a mile.
- Safety – while eliminating collisions in the intersection, traffic has to join the opposing traffic flow at the U turn in the fast lane.
- Expense – On high traffic roads, Michigan lefts may require an additional pair of traffic lights at each of the turnarounds.
- Visibility - Drivers inching up in the right lane of a Michigan Left may block the visibility of drivers attempting to make a turn from the left lane. The problem also sometimes happens when there is a backup in an opposing Michigan Left.
See also
External links
| Types of road junction | |
| Interchanges (grade separated) | Cloverleaf - Diamond - Directional T - Diverging diamond Parclo - Trumpet - SPUI - Stack |
| Intersections (at-grade) | Box junction - Continuous flow - Crossroads - Hook turn Jughandle - Michigan left - Roundabout - 3-way junction - Traffic circle |
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