Routing errors in London

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Re: Routing errors in London

Postby dknight212 » Sun Jul 28, 2013 8:17 am

woodvale wrote:The information that Twister is producing is wonderful, and I have no idea how it's done :? I do hope it leads to an early resolution of the problem.

Meantime, URs continue to be raised containing postcodes or addresses, presumably failed routing searches. Do we want to keep these for further evidence, or close them?

There also appears to be a spate of "off and on" routings at M25 junctions south of London (I haven't looked elsewhere 'cos that's outside my area), with two in the last three days at J6, Godstone. Are these likely to be related? I know it shouldn't happen - in the US, it appears to be illegal - but it does. Is there a known solution to this problem?

[EDIT - grammatical correction]


I've got an idea how it's done but am still amazed at the skill of some in the UK Waze community. Does anyone have any concerns that Waze HQ won't like calling the routing server so frequently?

The postcode errors do annoy me (and I'm sure the users are annoyed too). I presume most of them are failed routes but having seen some of the replies to UR comments I'm sure some of them are also user error. I'd continue to follow up the errors with each user as you have been doing, at the very least users do get some feedback.

The on and offs seem to be getting more frequent. Not just on motorways either. I presume Waze has somehow adjusted the algorithms and they will have to tweak them some more. Perhaps we should start up another thread (with screenshots).
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Re: Routing errors in London

Postby Twister-UK » Mon Jul 29, 2013 3:05 pm

dknight212 wrote:I've got an idea how it's done but am still amazed at the skill of some in the UK Waze community. Does anyone have any concerns that Waze HQ won't like calling the routing server so frequently?


You can thank Timbones, it's his Livemap navigation script I used as the basis for this one... And quite frankly, if Waze are concerned about one extra routing request per minute, then we've got more to worry about than the number of incomplete routes being returned.

I've now tweaked the script again to capture a bit of extra data based on some thoughts I had regarding the last set of results and why the fastest route might be falling short/failing entirely. Let's see what the next 24 hours brings us results-wise.
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Re: Routing errors in London

Postby dknight212 » Mon Jul 29, 2013 3:30 pm

Twister_UK wrote: And quite frankly, if Waze are concerned about one extra routing request per minute, then we've got more to worry about than the number of incomplete routes being returned.


That's what I would have thought but you never know. It will be so useful for them to see this thread.

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Re: Routing errors in London

Postby dknight212 » Wed Jul 31, 2013 4:33 pm

Chris - any updates on this?
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Re: Routing errors in London

Postby Twister-UK » Wed Jul 31, 2013 10:34 pm

Last testing session ran into some Firefox hassles, preventing the full log from being saved. I did still get a complete 24 hour cycle, but this one runs from 16:00 on Monday to 16:00 on Tuesday, as opposed to the 00:00-00:00 logs of previous tests...

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"Quickest" results - pretty much business as usual here...


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"Shortest" results - business unusual here though, for the first time the routing engine has started returning incomplete routes here too... Notice though how the incomplete routes are all longer, significantly so, than the complete ones - I wonder if there were some temporary road closures that morning, or could this have coincided with a mapping update?


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Endpoint plot - red for quickest routes, blue for shortest and purple for where both types of route had the same endpoint. The black-ringed purple dot lower-left is the true endpoint.
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Re: Routing errors in London

Postby woodvale » Fri Aug 09, 2013 11:19 am

Has there been any feedback from Waze on this?

I'm dealing with a UR at the moment where the user failed to get a route from Croydon Rd, Mitcham to UB7 0HB. I was able to generate a route in the middle of the day - the user informs that they failed to get a routing at around 7:30am and 4pm, which are in the "not working" time slots.

It rather defeats the primary reason for having Waze if it can't provide routes during peak travel periods.
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Re: Routing errors in London

Postby Twister-UK » Fri Aug 09, 2013 10:05 pm

Just noticed that in the request sent from livemap to the routing server, there's a timeout parameter which is set to 60000 (I'm assuming milliseconds). If I generate a modified request with a much shorter timeout parameter (<100) then I get an error response instead of the expected route. Given how long it can take the server to return results during the day, I wonder if the complete failures logged during my earlier testing were requests that timed-out before any routing results could be generated...
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Re: Routing errors in London

Postby Timbones » Sat Aug 10, 2013 9:47 am

It's possible. I've also seen some requests timeout, but after 2 or 3 more tries it sometimes works. It's as if some intermediate data is being cached internally so that subsequent requests are quicker.

You might want to experiment with the nPaths parameter too. Asking for one route might be less likely to timeout.

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Re: Routing errors in London

Postby Twister-UK » Sun Aug 11, 2013 11:20 am

I've just rewritten the routing tester in Delphi, which makes it easier to extract the data of interest as well as providing additional data not available to the scripted version and allowing the request parameters to be modified, so expect some more results to be provided over the next few days...
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Re: Routing errors in London

Postby Twister-UK » Mon Aug 12, 2013 9:55 am

First bit of data from the new routing tester...

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Using our trusty old test route once again, this plot shows the server response time (in milliseconds) to each routing request (grey line) with the usual yellow and red background areas denoting requests where the returned route was incomplete or non-existent. The black line is a 5-point averaging of the raw response times. The plot starts at 00:00 today and runs through to around 10:15.

What's interesting here is that throughout the period where no routes were returned, there's a corresponding drop in average response times, which suggests the server is simply rejecting the requests as they arrive rather than attempting to calculate any routes and then timing-out during the process (the request timeout parameter was set to the default 60000 for this test). Bear in mind that the response times recorded by the test client include network transit times for both the request and response packets, in addition to the processing time of the routing server itself, so the odd spike in raw response times may be down to network congestion rather than server slowdown.

Raw data captured during this test: http://chizzum.com/lmr/test1.zip
Last edited by Twister-UK on Mon Sep 02, 2013 9:06 pm, edited 1 time in total.
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