[Talk-us] Scrubbing route relations

Chris Lawrence lordsutch at gmail.com
Thu Oct 25 00:18:38 BST 2012

On Mon, Oct 22, 2012 at 11:00 AM, Paul Johnson <baloo at ursamundi.org> wrote:
> They use the same shield, and even TXDOT signs Farm Road and Ranch Road
> interchangeably.  They're definitely the same network.

While they use the same numbering sequence (as do State Highway Spurs
and State Highway Loops), they are definitely signed differently (with
either "Farm Road" or "Ranch Road" shields, or "F.M." or "R. M."
advance signage on guide signs), and most (if not all) routes are
either one or the other (there's a vague "zone" in the sense that FM
tends to be east of I-35 and RM tends to be west of I-35, but there
are exceptions based on the local agriculture - i.e. whether ranching
or farming takes place - although below San Antonio it's all FM, even
in ranching areas).

You can check the highway designation file for the correct designation
of specific routes.  If something else is on the sign, the local
district probably screwed up (several TxDOT district offices aren't
exactly known for their scrupulous observance of state standards).

Further confusing matters, some FM and RM roads are technically
designated as Urban Roads, but TxDOT always signs them as FM or RM
roads.  The designation file will probably tell you what it used to
be, which is usually what's on the signs.

Now, some FM roads are listed as Ranch Roads (and vice versa) in TIGER
for reasons I don't understand; probably data quality issues based on
transcribing from other maps (TxDOT's official state highway map, for
example, uses the same rectangular shield design for both route types;
the same [but hexagonal] deal with loops & spurs).

Chris Lawrence <lordsutch at gmail.com>

Website: http://www.cnlawrence.com/

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