December 20


Are U-Turns Safe?

By Mike Spack

December 20, 2016

Safety, Transportation Research Board of The National Academies Access Management Manual, U-turn, Wisconsin DOT

You want us to make a U-turn? In some situations the answer is yes. Requiring single occupant vehicles to make U-turns and subsequent right turns instead of direct left turns is a well-documented strategy for improving safety and minimizing delay along arterial corridors. According to the Transportation Research Board of The National Academies Access Management Manual, “U-turns are generally safer than direct left turns. A study of the safety and operational implications of U-turns versus direct left turns on multilane arterial roadways with a nonreversible median was conducted in Florida in 2000. The analysis of 250 sites revealed that right-turn plus U-turn maneuvers on six lane arterials exhibited a 17.8% lower crash rate and 27.3% lower injury/fatality rate than direct left turns. The study also found that U-turning drivers experience less delay than those making a direct left turn from a drive-way under high-volume conditions. The findings were statistically significant at a 95% confidence level.”

Minnesota’s State Statute (169.19 TURNING, STARTING, AND SIGNALING. Subd. 2. U-turn) says:

No vehicle shall be turned so as to proceed in the opposite direction upon any curve, or upon the approach to or near the crest of a grade, where such vehicle cannot be seen by the driver of any other vehicle approaching from either direction within 1,000 feet, nor shall the driver of a vehicle turn the vehicle so as to proceed in the opposite direction unless the movement can be made safely and without interfering with other traffic.

To summarize – if you can see down the road far enough to make a U-turn, it is safe and can help the overall operation of the roadway corridor.

  • We need to distinguish u-turns at signalized intersections from those at mid block non signalized intersections. I tend to believe u-turns at signals are less safe due to conflicts with opposing thru and x-street right turns. I will look at the Florida study and the TRB access manual to see if they did differentiate between signal and non-signal intersections.

  • A concept to address U-Turn risks was presented in the following article: Automobile Turn Indicator

    This article is based on a presentation (U-Turn Indicator) in the finals at the national (India) level Innovation Contest organized by National Geographic Channel in 2009-10.

    Automobile turn indicators currently in use have limitations in communicating the actual intended manoeuver a vehicle is likely to perform. For example, a vehicle intending to perform a U-Turn manoeuver uses the same indicator as that used for either a right or a left turn depending on whether a LHT (Left Hand Traffic) or a RHT (Right Hand Traffic) regime is in operation in the region in which it is moving. The same indicator is also used for indicating changing of lanes or permitting a passing (overtaking) manoeuver to a following vehicle on request. Some thoughts are presented in this article to overcome these and other limitations by using coloured LEDs to display the intended manoeuver.

  • The common confusion/risk of u-turn is who has the right of way against opposed turns, i.e., u-turn vs. right turn in USA/Canada, etc. or u-turn vs. left turn in UK/NZ, etc.

    I concur with Albert’s comment and am interested to know how authorities differentiate the rules for various intersection types.

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    Mike Spack

    My mission is to help traffic engineers, transportation planners, and other transportation professionals improve our world.

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