Subject: [GRASSLIST:659] Drive time analysis in GRASS?
Date: Tue, 8 Jul 2003 19:41:32 -0400 (EDT)
From: Brian McEntire <brianm@fsg1.nws.noaa.gov>
To: grasslist@baylor.eduHello folks,
I am interested in using GRASS/GIS to draw 5 minute driving time or
driving distance contour lines around a point. I believe a good amount of
road information is available in either of these sources:1) National Highway Planning Network - "(NHPN) is a 1:100,000 scale
network database that contains line features representing just over
450,000 miles of current and planned highways in the U.S. The NHPN
consists of interstates, principal arterials, and rural minor arterials."
[The file is available in ARC/INFO Interchange (.e00) format.]or 2) US Censes TIGER/Line 2k maps from the US Census
Does anyone know if a GRASS module has already been developed to
implement this? Or if implementing this in GRASS is a good idea to begin
with? I don't want to reinvent the wheel, but I haven't turned up any
open source or low cost applications that can do this.Thanks for any ideas!
Brian
Brian,
Your driving time contour problem seems to be a variant of the shortest
distance problem, which has a solution that keeps track of the cost of
getting to nearby vertices from a specified starting vertex. Maybe that
will help in your search for open source or low cost applications.
Also, I've written a vector library but haven't contributed it to GRASS
yet.
Concerning your data sources, I've worked a little with TIGER data and
am not aware of it containing road speed limit information. On the
other hand TIGER data has lots of CFCCs (Censor Class Feature Codes) for
roads that you could associate with assumed speed limits.
Greg