Friday, July 25, 2008
Avoid Highways
I often hear the question, "I want to plan a scooter trip: Is there a map service that will plot me a route that doesn't exceed 40mph?" Well, there isn't. Yet. The data just isn't there. This article from CNN explains the problem. It doesn't mention scooters, but the issue is the same. Sites like Mapquest were built for cars. And scooters, bikes and walkers follow different rules than cars. Different from each other, too. The demand for other modes of transportation wasn't anticipated, so the data wasn't collected. The data doesn't distinguish the many different speed limits on "local roads". But it sounds like that's going to be corrected. Eventually.
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The companies (Navteq, Tele Atlas, etc) that provide the map data store hundreds of parameters for each geographical coordinate that is mapped. It seems very unlikely that a fundamental parameter such as speed limit would be omitted. I don't think missing data is the problem. I think that the services offered by Mapquest and Google Maps are demand driven, and up until recently there just wasn't that much demand for these alternative routing options. Now that demand has increased Mapquest and the like will begin making better use of those huge map databases that they purchase.
Interesting all around. I checked the MapSource software that came with my Garmin GPS and there are various options in terms of vehicles with which to plan routes. Cars and motorcycles, however, are grouped together, and though there are settings for pedestrians and bicyclists, there's nothing, per se, for scooters. The options to avoid highways (interstate types) and toll roads work pretty well, though, to plan viable scooter routes.
Mr. Anonymous, Who told you that? Your GPS salesman? Perhaps I should elaborate and add the information I almost wrote in the entry.
My job is in the GIS profession. I work for an engineering and surveying company that has done some field work for one of the data collectors. I’ve seen the attributes. There aren’t “hundreds“. You exaggerate.
Check out this article: http://appdomains.slashgeo.org/application_domains/06/10/02/136255.shtml and the articles it links to. The points are collected by sub-contractors (like our company) at intersections. Those are used to periodically georeference existing data. Other than the X and Y, attributes collected are the street signs on each corner to confirm the names of the streets. That information is supplemented with aerial photographs (can’t read the speed limit signs there). They also use video footage provided by DOT’s to read signs between intersections. PennDOT does have this footage, but only for their roads. In PA, most back roads aren’t PennDOT roads. So who is going to find that speed limit sign on Becker Road?
Those back roads are owned and maintained by local municipalities with tiny budgets. Those back roads have not been video taped. Have you ever noticed the speed limit change along a road, at places other than intersections? 2000’ up a road is a heck of a time to find out that the speed limit is going up to 55. That is the information we scooter riders are most interested in. And that’s the data that isn’t collected. It’s a particular problem in PA.
Navteq's website says: "NAVTEQ maps provide a highly accurate representation of the detailed road network including up to 260 attributes...".
I would say that qualifies as "hundreds."
And I would say that "Up to" isn't "each geographical coordinate that is mapped". I'm sure they have some limited areas of very impressive data. But it isn't helping us in Lancaster County, which what this blog is concerned with.
One good place to find maps of back roads that don't have tons of traffic is www.Mapmyride.com. Using Google maps, cyclists from all over have posted maps and descriptions of decent routes. This site is great to use when I'm traveling somewhere and looking for a bike ride.
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