I'm trying to track down a routing problem which I believe is caused by "dodgy" data and will be pleased if you could offer some advice.

I'm trying to route from Squamish in B.C., Canada, to somewhere in North Vancouver using OSM data via maps from http://garmin.na1400.info/routable.php. (The coordinates are from Squamish at N49.70157 W123.15088 to Vancouver at N49.32185 W123.10776.) Both Garmin Map Source (GMS) and my Garmin 62CSX GPS fail to route in this direction. GMS gives me a cross country route and the GPS locks up at 100% calculating. However routing in the inverse direction works fine. By a series of routing origin binary chops in GMS I believe I've narrowed the problem down to this area in OSM (http://www.openstreetmap.org/?lat=49.401703&lon=-123.243516&zoom=18&layers=M). I've gone in to Potlatch2 and inspected the ways and relations of Highway 99 around that point but can't see anything that's obvious to me.

Any ideas or suggestions? Many thanks...

asked 03 May '11, 04:53

vagabond's gravatar image

vagabond
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edited 03 May '11, 16:13

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stephan75
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Another way to narrow it down is to try routing through some other source. e.g. An online map like http://maps.cloudmade.com/. Try routing between 2 points along the same road and check where it fails. That is, work out until you find a section it won't route past.

One thing to check with motorways is that you don't have one way sections going the wrong way. You probably can't see the oneway arrows on every section, even when zoomed in with Mapnik. Trying to route along what you think should be a straight section of road might show it up though.

For the link you gave, one of the bridges is missing the oneway tag, but the other is fine. (A missing oneway tag is probably not your issue though.)

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answered 03 May '11, 05:52

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Ebenezer
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3

I had a bit of a look around, and couldn't find any routing problems there, so maybe the problem has been fixed. The Garmin maps generated from that site can be a week or two older than the most recent data in OSM.

(03 May '11, 05:58) Ebenezer

When you have a routing problem on a specific hardware or software platform it can be useful to test the desired routing in other services or apps.

So have a look at Routing and try all other available websites (online) and apps (offline) that you can use and retry your route.

But also pay attention to the age of te mapping data belonging to each service, some may be outdated. ANd not all services or apps can deal with turn restrictions.

Problem still there?

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answered 03 May '11, 16:18

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stephan75
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I tried Cloudmade as suggested and that seems to route OK through the "dodgy" area. I inspected the edits in that area and some changes were made on 5 March 2011 with the author's comment "routing error on sea-to-sky. dualized carriage way.". I believe my dataset is from earlier than this date (12 Feb 2011) so that looks like the answer. I'll have another go at routing through there next time I refresh my map(s).

Many thanks for your suggestions.

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answered 04 May '11, 00:01

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vagabond
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You also have the OSM-based routing from user Lambertus, at http://www.yournavigation.org/ that is quite efficient; I'd recommend trying routing there if there is still a problem

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answered 04 May '11, 10:31

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Herve5
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question asked: 03 May '11, 04:53

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last updated: 04 May '11, 10:31

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