tertiary roads, TIGER and history

Posted by Dion Dock on 26 June 2012 in English (English)

I've heard some debate on the mailing lists about whether importing TIGER census maps into the US was a good idea. The con argument is people look at the map and figure it's good enough. The pro side is it put a lot of useful data in place.

Unfortunately, the quality of the TIGER data needs some improvement. For one thing, the highway= tag does not cover much ground between residential and motorway. There are lots of preferred roads, especially away from the cities, and you can't just look at a TIGER map and know which one to take.

I've been applying the highway=tertiary tag to lots of the backroads in Oregon. One thing I particularly like finding are roads that have been re-routed (which is a really neat thing to look for on old maps). Take a look at the underlying Bing! image and see how Seven Mile Hill Road used to take a bit of a meander to the south.

Comment from Paul Johnson on 29 June 2012 at 20:04

Generally speaking that should be OK for county and the main forest service routes. Secondary might be a better baseline if it's a state highway.

Comment from Tom Layo on 1 July 2012 at 13:23

At this point in the US map, the tag is less important than the road/feature being correctly placed on the map. While the map does look deceptively good only from a high zoom, the TIGER data is a net improvement. It would take many years for users to drive or bike every road to name streets, as already done by TIGER. And I grudgingly admit that most of the data regarding naming is good, and is now available to be fixed from a user anywhere.

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