[Talk-us] US highway classification
Nathan Mills
nathan at nwacg.net
Sat May 28 03:41:34 BST 2011
On Fri, 27 May 2011 21:26:53 -0500, John F. Eldredge wrote:
> I have driven on quite a few highways here in the USA that vary, mile
> by mile, in the number of lanes, how well they are graded, whether or
> not driveways connect directly to the highway, etc. This usually
> reflects their having been upgraded one piece at a time. Sections
> that pass through difficult terrain are often the last to be
> upgraded.
> Of course, whether or not a local politician has friends or relatives
> in the road-construction business makes a difference as well.
>
> If you classify these highways according to their importance to the
> transportation grid, then long sections, with variable physical
> characteristics, will be classified the same.
Obviously some element of judgment is required no matter what. As you
correctly point out, there is substantial variability in how roads are
built in the US. If the substandard section is small, one could perhaps
overlook it. If the upgraded section is small relative to the rest of
the highway, perhaps it should not be used in determining the
classification of the road. The intent here is not to classify solely on
physical characteristics, but there is clearly a difference in the
suitability of a road for long distance travel depending on whether it
is 2 lane or 4 lane divided, and that should be reflected on the map,
not just in tags.
I wouldn't downgrade a rural Interstate from motorway just because
there are two driveways in three hundred miles that might see use three
or four times a year. Nor would I upgrade a hundred miles of US highway
from primary merely because of a mile of divided highway and one grade
separated interchange.
Besides, if importance to the route network is the only consideration,
we ought not be using trunk at all or all US highways ought to be
classed as trunk. It seems obvious to me that neither can possibly be
the sole consideration.
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