[Talk-us] Better routing through better tagging?

[Tod Fitch]

Hi,

My experience the using OSM based routing has been that if the end points have good identifiers (names or addresses) and the roads are properly tagged, especially with correct maxspeed=* values, then the routes selected by http://www.yournavigation.org/index.php or http://map.project-osrm.org or the off line routing in OsmAnd are pretty good and the timing estimates fairly accurate.

I recently drove from the San Francisco bay area to Mammoth Lakes on the east side of the Sierra Nevada. Naturally I checked the above OSM based routing engines. Interestingly, they did not all agree on the route. Disappointingly they ignored the fact that the routes picked were closed for the winter. The big G competitor routed around the closed roads. :(

So I make a point of adding end point addresses and recording speed limits and tagging them. In this case, in addition to recording the speed limits on the route I took I also side trips up the east side of the closed roads to the gates and marked the gate locations. I also attempted to tag access information indicating that the route is unlikely to be open from November through May.

I attempted to follow the tagging suggested at http://wiki.openstreetmap.org/wiki/Key:seasonal and http://wiki.openstreetmap.org/wiki/Conditional_restrictions

I waited until the above routing engines had a chance to update and I built a new .obf file for OsmAnd. But the routes picked still ignore the seasonal access restriction.

Did I tag the seasonal access condition correctly? Here is one of the highways: http://www.openstreetmap.org/way/185218303

Do any of the OSM based routing sites or programs support seasonal access?

While CA-120, CA-108 and CA-4 are generally closed from the first snowfall (generally October or November) until Memorial Day weekend there is significant variation from year to year. CalTrans has online information about this but it is not easily tied into OSM. For example CA-108 is currently listed as "closed from 13 mi east of Strawberry (Tuolumne Co) to 5.3 mi west of the jct of us 395 /Sonora Pass/ - for the winter - motorists are advised to use an alternate route." See http://www.dot.ca.gov/cgi-bin/roads.cgi

I don't see a viable way of automatically updating OSM data per that type of report and don't think that it would be a good thing if it was possible. But maybe a permanent tag of some sort could give a link to a status provider so that routers could determine if the highway it usable.

I did not see a tag that looked like it could be used by a router to automatically check the highway status. Is there such a tag?

A bit off topic, but it is my understanding that all states now share road status information into a national database of some sort. This belief is bolstered by seeing that the CalTrans "QuickMap" at http://quickmap.dot.ca.gov shows current vehicle speeds on highways all the way to the east coast. Is there some way that that real-time information can be accessed by an open source based router?

Sorry for the long message and thanks for the feed back on tagging.

-Tod
-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/pkcs7-signature
Size: 1648 bytes
Desc: not available
URL: <http://lists.openstreetmap.org/pipermail/talk-us/attachments/20140329/95934aa8/attachment.bin>