Advice please on restricting u-turn for a UR

[SteveSnail]

Hi all

After some advice on the following UR please:

https://www.waze.com/editor/?env=row&lon=-0.76256&lat=52.03675&layers=11173&zoom=6&mode=0&mapProblemFilter=0&mapUpdateRequestFilter=1&venueFilter=0&update_requestsFilter=truemaar&problemsFilter=false&u pdate_requestsFilter=false&lo%20...%20ueFilter=0&apProblemFilter=0&%3BapProblemFilter=0maar&mapUpdateRequest=7352342

The issue is that the intersection of Avebury Boulevard and Witan Gate should not allow u-turns but due to the nature of the roads there I’m unsure how to restrict these to achieve this. Restricting a right turn on the segment in one direction to prevent the u-turn then affects the right turn from a different direction if that makes sense. On checking streetview, it looks like the u-turns are restricted from all 4 directions.

Can somebody advise further please?

Thank you

[atrophicshiner]

This junction is set up correctly to trigger Waze’s built in u-turn prevention, it meets all 3 requirements;

• Three segments: The U-turn is a reversal of driving direction through three segments:
  an incoming segment (A), a single median segment (B) and an outgoing segment (C).
• Short median: The median segment (B) is shorter than 15 meters (49.21 feet).
  As a safety margin, leave a 1 m buffer zone by using 14 meters (45.93 feet) or less.
• In/out parallelism: The in and out segments (A and C) are within ±5° of parallel to each other.

That being said I’m not sure how reliable this is immediately after Waze make a route recalculation.

You might try a bow-tie setup but that might be as complicated, it’d look something like this…

[PealRinger]

I believe in the UK the median segments need to be <10m to trigger the u-turn prevention, so bringing the roads slightly closer together at the junction may do the trick.

This has worked for me in the past. See this thread U-turns on dualled roads - anything changed?

[Timbones]

@PealRinger

I believe in the UK the median segments need to be <10m to trigger the u-turn prevention, so bringing the roads slightly closer together at the junction may do the trick.

This wiki page says that the threshold is <15m (49 ft).

[PealRinger]

@Timbones

This wiki page says that the threshold is <15m (49 ft).

True, but it’s said that for a long time.

I’m only going on what a very respected editor once suggested to me in another thread, saying that the wiki might be wrong and to use 10m instead. Worked for me at the time.