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List:       postgis-users
Subject:    Re: [postgis-users] Making Tiger shapefiles routable
From:       Stephen Woodbridge <woodbri () swoodbridge ! com>
Date:       2012-03-28 23:41:57
Message-ID: 4F73A1C5.5080903 () swoodbridge ! com
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On 3/28/2012 6:58 PM, Hilton Long wrote:
> Has a set of standard queries been developed to make Tiger shapefiles
> routable? It would need to eliminate gaps and ensure that all end nodes
> and intersecting nodes corresponded with each other.

This might be better asked in the pgRouting list, but I'll address it 
here and cc that list.

I have loaded tiger data into pgrouting and you do not need to mess with 
the end points, just run the just process it like any shapefile and it 
will work for want it is worth.

The issue with Tiger is that the data is not really suitable for 
routing, I was using it for drivetime analysis where the results are 
approximate and that worked fine for my use cases.

Here are some of the problems with Tiger data:

* segments are not flagged for oneway streets
* there is no zlevel information at intersections ( so it will generate 
routes like drive to an overpass and turn right onto the underpass )
* the road classifications do not allow you to set the average speed for 
a road class very accurately, although this is minor compared to the 
first two.

-Steve W
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