Michigan left

A Michigan left is an at-grade intersection design that replaces each left turn at an intersection between a (major) divided roadway and a secondary (minor) roadway with the combination of a right turn followed by a U-turn, or a U-turn followed by a right turn, depending on the situation.

For the Arkells album, see Michigan Left (album).
Standard design on a wide median.[1]
Stylized depiction of the design in Grand Haven, Michigan, at US 31 and Robbins Road (north to the right), showing the additional area necessary to make a turn on a narrow median.[1] 43°2′40.18″N 86°13′12.57″W

Terminology

This intersection design was given the name "Michigan left" due to its frequent use along roads and highways in the U.S. state of Michigan since the late 1960s.[2] In other contexts, the intersection is called a median U‑turn crossover or median U‑turn.[1][3][4] The design is also sometimes referred to as a boulevard left,[5] a boulevard turnaround,[6] an indirect left turn,[2][7] a Michigan loon,[8] a P‑turn or a "ThrU Turn" intersection.[9][10]

Description
Two versions of signs posted along an intersecting road or street at an intersection
Top: most commonly used; state of Michigan standard[11]
Bottom: lesser-used variant

The design occurs at intersections where at least one road is a divided highway or boulevard, and left turns onto—and usually from—the divided highway are prohibited. In almost every case, the divided highway is multi-laned in both directions. When on the secondary road, drivers are directed to turn right. Within 1⁄4 mile (400 m), they queue into a designated U-turn (or cross-over) lane in the median. When traffic clears they complete the U-turn and go back through the intersection. Additionally, the U-turn lane is designed for one-way traffic.

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.

When vehicles enter the cross-over area, unless markings on the ground indicate two turning lanes in the cross-over, drivers form one lane. A cross-over with two lanes is designed at high-volume cross-overs, or when the right lane turns onto an intersecting street. In this case, the right lane is reserved for vehicles completing the design. Most crossovers must be made large enough for semi-trailer trucks to complete the crossover. This large cross-over area often leads to two vehicles incorrectly lining up at a single cross-over.

A Michigan left generally allows through traffic on the minor crossroads to proceed straight across the major road or highway, especially on the more heavily-traveled minor roads.

Its design also is promoted as part of the Federal Highway Administration's Every Day Counts initiative which started in 2011.[12]

Variations

Narrow median

When the median of a road is too narrow to allow for a standard Michigan left maneuver, a variation can be used that widens the pavement in the opposite direction of travel. This widened pavement is known as a "bulb out"[9] or a "loon" (from the pavement's aerial resemblance to the aquatic bird).[8] Such a design is sometimes referred to as a Michigan loon; in Utah, as a ThrU Turn, where you pass through the intersection before a U-Turn.[9]

Grade separation

In Guadalajara, Mexico, there is a grade-separated variation of this setup at the intersection of Mariano Otero Avenue and Manuel Gómez Morín Beltway (20.630666°N 103.434981°W / 20.630666; -103.434981).[13] Traffic flowing through Mariano Otero Avenue is routed onto an overpass above the beltway, with two access roads allowing right turns in all four possible directions; the U-turns, meanwhile, are built underneath the beltway and allow the left turn movements from Mariano Otero Avenue to the beltway.

Superstreet
Main article: Superstreet

A variation of the Michigan left that prohibits through traffic on minor roads from crossing the major road or highway, is most commonly called a superstreet or a "restricted crossing U‑turn" (RCUT).[14] In contrast to the standard Michigan left, left turns from the major road or highway to minor roads are usually allowed, although there is a variation that prohibits such turns.

Examples

Angola

The capital city of Angola, Luanda, makes widespread use of a simplified variant of this type of intersection on its two- and three-lane, median-separated throughways instead of using traffic lights. Larger junctions use this intersection type instead of much more costly grade-separated interchanges.

Australia

In Australia, where traffic drives on the left, the Victorian state government introduced the "P-turn", similar to the Michigan left, at one intersection in 2009. This requires right-turning vehicles to turn left then make a U-turn. As of May 2015, the intersection in the southeastern Melbourne suburb of Frankston remains the only one of its kind in the state, and local residents have called for its removal.[15]

On April 16, 2018, a P-turn will be introduced at the intersection of Hoddle Street and Johnston Street in Abbotsford, Victoria. Additional P-turns will be added along Hoddle Street to attempt to ease congestion.

Brazil

The Michigan left is a commonly used design in Brazil especially in São Paulo and Paraná.

Canada

The design has been proposed in Toronto, Ontario, to relieve motorists who wish to make a left-turn on roadways that will contain a proposed streetcar line by the Transit City project.

In Ottawa, Ontario, a Michigan left exists to proceed from Bank Street to Riverside Drive in both directions.

In Calgary, Alberta, a Michigan left allows motorists to access northbound Crowchild Trail from eastbound Bow Trail via 10 Ave SW.

Another Michigan left exists in Windsor, Ontario, on Huron Church Road, just north of the E.C. Row Expressway, where a narrow-median variant put in place years ago is now seldom used due to the realignment of the expressway in conjunction with the construction of the Herb Gray Parkway.

Hong Kong

This is the design at some busy junctions in Hong Kong. In Hong Kong Island examples include the junction of Fleming Road and Harbour Road in Wan Chai North, and the junction of Hennessey Road and Canal Road Flyover in Wong Nai Chung. In Kowloon this design exists between Cheong Wan Road and Hong Chong Road/Salisbury Road.

Mexico

U-turn intersections are very common throughout Mexico, particularly in Mexico City.

United Kingdom

A similar style P-turn is used in the junction of the A4 Great West Road and A3002 Boston Manor Road in Brentford, England.

United States

In 2013, Michigan lefts were installed in Alabama for the first time, in several locations along heavily traveled U.S. Route 280 in metro Birmingham.[16]

Tucson, Arizona, began introducing Michigan lefts in 2013, at Ina/Oracle and on Grant Road. Their reception has been mixed.[17]

In November 2018, the Ada County Highway District completed work on a ThrU-turn intersection at the State Street/Veterans Memorial Parkway/36th Street intersection in Boise, Idaho.[18]

The design is relatively common in New Orleans, Louisiana, and its suburb Metairie, where city boulevards may be split by streetcar tracks,[19] and suburban thoroughfares are often split by drainage canals.[20] Some intersections using this design are signed similarly to those in Michigan, but with more descriptive text,[21] however in some cases the only signage is "No Left Turn" and drivers are left to figure it out for themselves.[22]

Since the redevelopment of the intersection between University Boulevard (MD 193) and Colesville Road (US 29) in Silver Spring, Maryland, a Michigan left has been used to increase efficiency of traffic through an otherwise underdeveloped and congested intersection. Due to its proximity to the Capital Beltway, heavy traffic is handled more safely and efficiently.

The Michigan Department of Transportation first used the modern design at the intersection of 8 Mile Road (M-102) and Livernois Avenue[23] (42.4461°N 83.141°W / 42.4461; -83.141 (M-102 (8 Mile Road) at Livernois Avenue))[24] in Detroit in the early 1960s. The increase in traffic flow and reduction in accidents was so dramatic (a 30–60% decrease[25]) that over 700 similar intersections have been deployed throughout the state since then.[26]

North Carolina has been implementing Michigan lefts along US 17 in the southeastern part of the state, outside Wilmington.[26] In 2015, a Michigan left was constructed at the intersection of Poplar Tent Road and Derita Road in the Charlotte suburb of Concord.

Columbus, Ohio introduced a Michigan left at the intersection of SR 161 and Strawberry Farms Boulevard in 2012.

At least two Michigan lefts have existed in Texas. One was located at the intersection of Fondren Road and Bellaire Boulevard in Houston from the 1980s through 2007, when it was replaced with conventional left-turn lanes. Another was built in mid-2010 in Plano at the intersection of Preston Road and Legacy Drive.[27] In January 2014, the city announced plans to revert the turn to a traditional intersection as a result of drivers' confusion. A section of State Highway 71 east of Austin-Bergstrom International Airport at FM 973 in Austin, Texas did have a signalized Michigan U-turn that was constructed in 2014—this was a temporary fix until the SH71 tollway over SH130 (including the re-routing of FM973) was completed in early 2016. There are multiple Michigan left turns currently being used along US 281 north of Loop 1604 in San Antonio. These were adopted as a short-term solution for traffic issues as development expanded north, but will likely be phased out as US 281 is elevated.

The city of Draper, Utah, a suburb of Salt Lake City, announced in 2011 that it would be building Utah's first "ThrU Turn" at the intersection of 12300 South and State Street, just off Interstate 15 through Salt Lake County. Construction began in summer 2011 and was completed in fall 2011.[9][28][29] Other similar intersections were implemented in South Jordan[30] and Layton.[31]

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. Because 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.[1]

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.[1] One minor disadvantage of the Michigan left is the extra distance required for the motorist to drive. Sometimes the distance to the turnaround is as far away as 1⁄4 mile (400 m) past the intersection. This design leads to each motorist driving an additional 1⁄2 mile (800 m) to make a left turn. It also results in left-turning vehicles having to stop up to three times in the execution of the turn.

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See also

References
  1. Federal Highway Administration (August 2004). "Alternative Intersection Treatments". Signalized Intersections: Informational Guide. Federal Highway Administration. Archived from the original on May 10, 2009. Retrieved August 1, 2011.
  2. Michigan Department of Transportation (July 19, 2010). "Michigan Lefts". Michigan Department of Transportation. Retrieved December 20, 2010.
  3. Federal Highway Administration (August 2014). "Median U-Turn Intersection Informational Guide" (PDF).
  4. North Carolina State University (August 1, 1999). "Unconventional Left-Turn Lanes Reduce Traffic Accidents, Congestion" (Press release). North Carolina State University. Archived from the original on March 25, 2007. Retrieved December 20, 2010.
  5. Indiana Department of Transportation. "Traffic Operations: Median U-Turns". Indiana Department of Transportation. Retrieved June 24, 2017.
  6. City of Farmington Hills, Michigan (October 18, 2001). "Minutes, Planning Commission Public Hearing, September 20, 2001" (PDF). City of Farmington Hills, Michigan. Archived from the original (PDF) on September 27, 2007. Retrieved August 1, 2011.
  7. Hall, Jocelyn (September 18, 2015). "M-20 Traffic Restrictions at Leaton Road Starting Sept. 23" (Press release). Michigan Department of Transportation. Retrieved February 4, 2019. Indirect left turns, or Michigan Lefts, near the intersection will be available.
  8. Hughes, Warren; Chappell, Debra; Chen, Shyuan-Ren (Clayton) (January 2005). "Geometric Design Treatments". Innovative Intersection Safety Improvement Strategies and Management Practices: A Domestic Scan. Federal Highway Administration. Retrieved August 17, 2013.
  9. Utah Department of Transportation. "Overview". Thru Turn Intersection. Utah Department of Transportation. Archived from the original on June 23, 2012. Retrieved September 24, 2011.
  10. Doctor, Mark; Shaw, Jeff; Merritt, George (April 4, 2013). "Intersection and Interchange Geometrics" (PDF). Every Day Counts 2 Spring Virtual Summits - 21st Century Solutions (PDF). Federal Highway Administration. Retrieved August 17, 2013.
  11. Michigan Department of Transportation, Traffic and Safety division (2012). "Standard Highway Signs: Route Marker Signs". p. 101. Sign M8-5.
  12. Schroeder, Bastian; Cunningham, Chris; Ray, Brian; Daleiden, Andy; Jenior, Pete; Knudsen, Julia (August 2014). Diverging Diamond Interchange Informational Guide (PDF). Washington, DC: Federal Highway Administration Office of Safety.
  13. Google (December 20, 2010). "Mariano Otero Avenue and Manuel Gómez Morín Beltway, Guadalajara" (Map). Google Maps. Google. Retrieved December 20, 2010.
  14. Federal Highway Administration (August 2014). "Restricted Crossing U-Turn Intersection Informational Guide" (PDF). p. 10.
  15. Tatman, Christian (May 15, 2015). "Roads Minister Luke Donnellan says Frankston's P-turn will remain". Frankston Standard Leader. Retrieved January 7, 2015.
  16. Smith, Mike (September 5, 2013). "US 280: 'Michigan Left' U-turn at Valleydale Scheduled to Be in Effect for Friday Morning Commute (animation)". The Birmingham News.
  17. "Little Love for Michigan Left". Arizona Daily Star. October 14, 2013. Retrieved March 3, 2014.
  18. "State Street/Veterans Memorial Parkway/36th Street Intersection". Ada County Highway District. Retrieved March 11, 2019.
  19. Google (May 17, 2013). "S Claiborne Ave and S Carrollton Ave, New Orleans" (Map). Google Maps. Google. Retrieved May 17, 2013.
  20. Google (February 1, 2013). "W Metairie Avenue and Cleary Avenue, Metairie" (Map). Google Maps. Google. Retrieved February 1, 2013.
  21. Google. "W Metairie Avenue near Cleary Avenue, Metairie". Google Street View. Google. Retrieved February 1, 2013.
  22. Google. "Northbound on S Carrollton Ave at S Claiborne Ave, New Orleans". Google Street View. Google. Retrieved May 17, 2013.
  23. "Revisiting the Origin of the 'Michigan Left'". Michigan Radio. September 15, 2014. Retrieved November 26, 2017.
  24. Google. "8 Mile Road and Livernois Avenue" (Map). Google Maps. Google.
  25. Klinefelter, Quinn (October 5, 2015). "CuriosiD: Where Did the Michigan Left Come From?". Detroit: WDET-AM. Retrieved November 25, 2017.
  26. Sweeney, Kate. "The Michigan Left Superstreet: Heading Eastbound: A Midwestern traffic pattern takes a detour to North Brunswick County". North Brunswick Magazine. Retrieved November 26, 2017.
  27. Kim, Theodore (March 23, 2010). "Officials Worry that 'Michigan Left Turn' at Plano Intersection Will Confuse Drivers". Dallas Morning News. Retrieved December 20, 2010.
  28. Davidson, Lee (November 11, 2011). "Newfangled Intersection to Open Monday in Draper". The Salt Lake Tribune. Retrieved August 17, 2013.
  29. "U-Turns Replace Left Turns at Draper intersection". KTVX. November 14, 2011. Retrieved August 17, 2013.
  30. "'Thru Turn' in Effect at Bangerter and 7800 South Intersection". West Jordan Journal. Archived from the original on February 9, 2013. Retrieved June 11, 2012.
  31. Utah Department of Transportation. "Layton Improved UDOT Open House Presentation". Utah Department of Transportation. Archived from the original on July 1, 2014. Retrieved March 3, 2014.
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