Michigan Left - Applicable Traffic Studies

Applicable Traffic Studies

This type of intersection configuration, as with any engineered solution to a traffic problem, carries with it certain advantages and disadvantages and has been subject to several studies.

Studies have shown a major reduction in left-turn collisions and a minor reduction in merging and diverging collisions, due to the shifting of left turns outside the main intersection. In addition it reduces the number of different traffic light phases, significantly increasing traffic flow. Since separate phases are no longer needed for left turns, this increases green time for through traffic. The effect on turning traffic is mixed. Consequently, the timing of traffic signals along a highway featuring the design is made easier by the elimination of left-turn phases both on that highway and along intersecting roadways contributing to the reduction of travel times and the increased capacity of those roadways. Finally it has been shown to enhance safety to pedestrians crossing either street at an intersection featuring the design, since they only encounter through traffic and vehicles making right turns. The left-turning movement, having been eliminated, removes one source of potential vehicle-pedestrian conflict. One minor disadvantage of the Michigan left is that a motorist has to go 100 feet (30 m) or so in the opposite direction before turning left.