How the 'Michigan Left' turn became a thing
Some love it. Some hate it. It's the Michigan Left. Almost as controversial as roundabouts! (This article first appeared in the Morning Report newsletter. Sign up for it here)
In our state, we have a thing called the "Michigan Left," and it has nothing to do with politics.
The unique "left turn" design is a true Michigan thing that every Michigander knows about. But how did it become our thing? And is it anymore effective than a normal protected left turn?
Let's start with the basic description of what it is: Where a Michigan Left is in place, left turns at the intersection are not allowed. Instead, to turn left, you must drive straight or turn right, then make a U-turn at a median crossover, guided by sign like the one at right.
Michigan Lefts have been part of Michigan roadways since at least the late 1960s. They're often called a median U‑turn crossover or median U‑turn. Here are some FAQs I found from MDOT:
Why has the State of Michigan adopted these?
Research and experience have shown that the Michigan Left relieves congestion; it increases safety by reducing the number and severity of crashes. Whenever MDOT plans work on a boulevard (divided roadway), engineers will consider incorporating Michigan Lefts.
How do Michigan Lefts compare in efficiency to conventional intersections?
They provide 20 to 50 percent greater capacity than direct left-turns. They reduce average delays to left-turning vehicles and through-traffic.
What about pedestrians?
Michigan Lefts increase pedestrian safety. Divided roadways are safer for pedestrians in general, since they can cross one direction of the roadway at a time and wait at the median to safely finish crossing. Where direct left turns are prohibited, the traffic signal can remain green for pedestrian crossings longer.
What's the effect on crashes?
On roadways where crossovers and Michigan Lefts have been added, crashes have been reduced 30 to 60 percent overall. The greatest reductions are in rear-end and head-on crashes during left-turns (60 to 90 percent reduction) and right-angle crashes (60 percent reduction). Slight increases are noted for two other crash types. Non-left-turn rear-end crashes increase by approximately 25 percent, and fixed-object crashes increase by approximately 20 percent.
How does MDOT determine where to build a Michigan Left?
Engineers study the crash history and traffic at major intersections along a roadway. Indirect left turns can be built on divided roadways with any number of lanes (i.e., 4-lane, 6-lane, or 8-lane).
Michigan Lefts are most often used in urban situations where congestion and crashes are more common. They are not used on freeways or limited-access roads of any kind. U-turns and other movements through freeway medians are strongly discouraged.