Michigan Highways: Since 1997.

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The Michigan Left

Contents: Introduction | How it Works | History | Photos & Plans | Other Thoughts

Often maligned, often misunderstood, the Michigan Left turn is an operation which causes much consternation among out-of-state drivers and nary a second thought from locals. Developed in Michigan in 1960 (see History), these turning set-ups exist across the entire state, from Niles to Escanaba and from Detroit to Marquette. (Yes, the Upper Peninsula has Michigan Lefts! At last check, about 30 individual turnarounds.) As of 2010, one MDOT document noted, "In Michigan, there are more than 425 miles of median with directional crossovers on the state highway system."

Michigan Left SignsThe Michigan Left was developed to avoid the interlocking left-turn movements along divided highways. In this way, the only turning movements allowed at such an intersection are right-hand turns. Traffic lights can be placed at busier Michigan Left intersections if warranted. For the most heavily-used "crossovers," specialized traffic signals may be placed to ensure traffic does not back up on the highway waiting to turn left.

The Michigan Left is often railed against by visitors and those moving to Michigan from other areas. While it is often contrasted with other intersection improvement solutions, such as the New Jersey Jughandle, New England Percentage of crashes by driveway movement.rotaries, the standard roundabout, and even grade-separated interchanges, studies over the past 50 years keep proving the Michigan Left's worth. Those studies show the average wait times at Michigan Left intersections are much shorter than if that same intersection had a traditional four-phase traffic signal with protected left-turn movements. Plus, the types of collisions which occur at Michigan Left intersections cause less damage, fewer injuries, and costs drivers less. Additionally, the National Highway Institute Research Center reports that "nearly 75% of all access-related crashes [to and from driveways from the main highway] are left turns. The left-turn movement into a driveway, without the benefit of a signal, accounts for 47% of the crashed associated with driveways. Twenty-seven percent of the crashes were turning left out of the driveway. Only 26% of driveway crashes are right-turns (with 16% in and 10% out)." (See graphic at left.)

As for those who constantly complain and insult the traffic engineers who continue to install Michigan Lefts, think about it this way: If Michigan Lefts were truly judged to be more dangerous or ineffective at their purpose, why are they still proliferating a half century later? And why are so many more states and other nations around the world using them or slight variations of them? Hmmm...

How it Works

Michigan Left Turn Image
 

Red Line traffic on the divided highway cannot turn left directly at the crossroad intersection. To accomplish the left turn, the divided highway traffic moved to the left lane, continues past the crossroad, and turns left into a "median crossover," usually placed about 660 feet beyond the intersection. When traffic clears sufficiently, the left turn onto the opposite direction of the divided highway is completed. The driver then moves to the right lane and turns right onto the crossroad, thus completing the traffic movement.

Green Line traffic on the crossroad wishing to turn left onto the divided highway first turns right onto that highway, moves to the left lane and turns left into the "median crossover" approximately 660 feet from the intersection. When traffic clears sufficiently, the left turn onto the opposite direction of the divided highway is completed.

History of the Michigan Left

The following is excerpted from the publication "The State of Michigan Trunk Line Story," Third Edition, by Stanley D. Lingerman, P.E. Fellow Member, August 15, 1996. From the second chapter titled "U.S. and Super Highways," Mr. Lingerman relates just how the Michigan Left came to be:

The Super Highway, which was originally designed for use in the Detroit area as part of the United States Highway Program of the late 1920s, proved with time to have some operational problems that developed from the traffic growth following World War II.

In 1960, in order to avoid the interlocking of left-turn movements, a number of major intersections along Telegraph Road [US-24] in Wayne County were designed as Super Highway with directional crossovers. The purpose of the directional crossovers was to remove the left turns from the major intersections. The crossovers were placed in the median island about 350 feet from the cross street. Joseph Hobrla, the Department's Signal Engineer, was dissatisfied with the traffic flow characteristics of these intersections on Telegraph Road. He and Joseph Marlow, the District Traffic Engineer [for the State Highway Department], decided to experiment with the westbound Eight Mile Road [M-102] left turn at Livernois Avenue in Detroit. A directional left-turn crossover was constructed in the median of Eight Mile Road at a point 660 feet west of Livernois. A traffic signal was placed on eastbound Eight Mile Road at Livernois to handle the right-turn movement. The operation has proved to be so successful that 700 directional crossovers have been constructed on the trunk line system throughout the state.

The Michigan Left turn treatment continues to be implemented around the state whenever deemed necessary to improve the flow of traffic. In the early 1990s, for example, M-44/East Beltline Ave in the Grand Rapids area, from I-96 northerly to Plainfield Ave, was completely reconstructed as a divided highway with Michigan Left crossovers. Also in West Michigan, US-31 from Holland to Grand Haven is slowly being upgraded to include Michigan Lefts at the busier intersections.

Although Michigan has been using the Michigan Left treatment for over five decades, other states had been slow to experiment with this type of traffic control. However, in recent years other states and municipalities have begun to implement Michigan Lefts due to shrinking transportation budgets and increasing traffic congestion. For example, the North Carolina Department of Transportation has been actively implementing Michigan Lefts as a part of their "Superstreet" program and municipalities in Arizona have gone so far as to rename them as "Arizona Boulevard" turns.

Photos & Plans

Other Thoughts