why no left turn at intersection

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Re: why no left turn at intersection

Postby bz2012 » Sun Mar 24, 2013 5:40 pm

Agreed, but right, left, straight (long route) would seem longer than straight, left (short route), especially when the long segments are added in, along with waiting for a chance to make that 'U' turn safely.

Granted, there may be a 'right on red after stop' advantage, at that intersection that we are not seeing.
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Re: why no left turn at intersection

Postby bz2012 » Sun Mar 24, 2013 5:29 pm

CBenson wrote:Its a routing algorithm issue.
The live map shows routing algorithm fastest route. But waze routes fine if the navigation type is set to shortest.
Bluebonnet.jpg

Thus, I do not believe that any correction the map is warranted. My understanding of the issue is that with the speed data that waze has, waze has calculated that on average it is faster to take the right/U than it is to wait at the light to make the left turn. Sometimes you can fix this by actually driving the U route so waze gets better data.

I'm not sure that this is considered a "problem" to be fixed, as based on the waze data it seems that it is the fastest route.


Hmmmm That makes sense until I take a look at the actual figures.

I would like to know how they compared the two routes and come out with faster for the longer. Something is seriously wrong with their algorithm!

Neglecting time lost making turns, here is what I calculate for time to get to the node where the left turn is made on the short route:

segment 1 (short route) Length: 15 meters
Average speed for segment*
B->A: 20km/h (12.4mph or 5.543 meters/second) = 2.7 seconds
total 2.7 seconds

segment 1 (longer route)Length: 178 meters
Average speed for segment*
A->B: 54km/h (33.6mph or 15.021 m/s) = 11.85 seconds
segment 2 (longer route) Length: 18 meters
Average speed for segment*
A->B: 6km/h (3.7mph) = 10.88 seconds
segment 3 (longer route) Length: 81 meters
Average speed for segment*
A->B: 11km/h (6.8mph) = 26.64 seconds
segment 4 (longer route) Length: 91 meters
Average speed for segment*
A->B: 9km/h (5.6mph) = 36.35 seconds
total 85.7 seconds

85.7 seconds seems quite a bit slower than 2.7 seconds!

I think another possible 'fix' is to make the 'crossover' on the long route a 'parking lot road'.
Any objections to this?
Last edited by bz2012 on Sun Mar 24, 2013 5:34 pm, edited 1 time in total.
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why no left turn at intersection

Postby bz2012 » Sun Mar 24, 2013 1:04 pm

A user asked:
Problem: why not turn left at light from bluebonnet onto airline
Reported on: March 21
https://www.waze.com/editor/?lon=-91.06 ... TTTFTTTTFT
All turns are allowed (except the U turn).
2013-03-24_073940.png
2013-03-24_073940.png (20.62 KiB) Viewed 4050 times
Road types look OK.
Live map shows the same crazy routing that the driver was getting.
2013-03-24_071736.png
2013-03-24_071736.png (22.51 KiB) Viewed 4053 times


I think the intersection had been working.

Questions:
    have recent changes in routing algorithms broken the intersections?
    What is the 'best way' to fix it?
I am tempted to 'add a left turn lane', perhaps as simple as this,
2013-03-24_072001.png
2013-03-24_072001.png (206.11 KiB) Viewed 4055 times
perhaps starting earlier, where the 'left turn only' pavement markings begin, even though the 'best practice guidelines' frown upon such things.

If I KNEW it was a routing algorithm problem and would soon be fixed, I would just leave it as is and mark it solved.
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Re: why no left turn at intersection

Postby Bigbear3764 » Sun Mar 24, 2013 6:12 pm

bz2012 wrote:
When I drive, I try to avoid making U-turns, even when legal. I would rather go down a side street or into a parking lot to turn around.


Don't drive in Michigan. They make you go past the street to make a left, loop around and come back to make a right. Now most busy intersections have a stop light for the Michigan left.





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Re: why no left turn at intersection

Postby aplycon » Wed Jan 29, 2014 4:44 am

Last edited by aplycon on Mon Feb 03, 2014 1:44 am, edited 9 times in total.
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Re: why no left turn at intersection

Postby aplycon » Wed Jan 29, 2014 1:00 am

sketch wrote:Champs have to submit each occurrence manually, so the best data is gonna come from things you personally experienced. If any of y'all come across one of these yourself, leave a UR and make note of the time/date and your approximate route at that time, then post all that here, if you like.


How about URs that others have posted that fit the same problem?

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Re: why no left turn at intersection

Postby aplycon » Wed Jan 29, 2014 12:24 am

sketch wrote:Staff have actually been collecting data about specific occurrences of this, not sure how much they need, but it seems the more the better. Staff are currently working on a prevention mechanism for this type of thing.


are they collecting said data from this thread? if so, should we keep posting all occurrences we run into?
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Re: why no left turn at intersection

Postby aplycon » Tue Jan 21, 2014 1:31 am

I have examples of this popping up in south Florida as well. I'm glad I found this thread to see how frequent this issue has been occurring. Hoping that CBenson's latest post from Waze staff will prove to rectify this routing issue. Waze should almost always chose the left turn. I think that the driver should make their own decision approaching a light to wait for a long-queued left or a right on red + U turn based on the traffic and their driving style. I drive more aggressively and may chose that right on red "shortcut" but most people I know (and when are my passengers) denounce that practice as impatient and risky.

UR from Jan 1 in Coconut Creek, FL:
Image
That right turn + U turn adds nearly 1km to the route instead of just taking the left. How could that possibly be time-saving?
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Re: why no left turn at intersection

Postby AndyPoms » Sun Aug 18, 2013 7:49 pm

That intersection in Torrington has been causing issues for a while - I finally removed & rebuilt that segment of Christopher Rd as it was showing REALLY bad speed data (like 2mph bad)... Give it some time.
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Re: why no left turn at intersection

Postby AlanOfTheBerg » Tue Oct 22, 2013 5:04 am

CBenson wrote:Why do I get different routes when I ask for the same route at the same time "earlier today?" If I just keep clicking find routes it switches back forth seeming at random.

Could they be doing what I've jokingly suggested in the past and doing some randomizing/round-robin algorithm to simply spread traffic around relatively similar routes?
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