[Talk-us] "highway" tags in the US
hawke at hawkesnest.net
Tue Mar 4 23:32:45 GMT 2008
Karl Newman wrote:
> On Tue, Mar 4, 2008 at 10:26 AM, Alex Mauer
> Hmm... Then why are all the generic roads from TIGER marked as residential?
DaveH answered this one.
> Other roads change speed as they enter urban places (e.g. primary roads
> may go from 55 down to 25 to pass through a hamlet) Why shouldn't
> tertiary be the same? It's all about the relative status of a road to
> the roads around it.
> But the residential road is slow for its entire length, whereas your
> hamlet example is only slow while in the town.
Regardless of speed limit (for which we have a separate tag anyway)
there are some residential/commercial/industrial/rural roads which are
more significant than the ones around them. I see no reason to simply
discard the existence of the tertiary tag just because it's a
residential area which is being mapped, and because the speed limit is
the same. The speed limit is not the only distinguishing factor.
You appear to be suggesting that a road with a 25 mph speed limit cannot
be tertiary, but a primary road can be 25 mph for part of its length.
That doesn't make sense to me.
> Hmm...it seems to me that perhaps you're writing this from a perspective
> of "what a driver using the road might expect", while I'm coming from a
> perspective of "how should this road be tagged". Is that the case?
> "How should this road be tagged" needs to consider the expectations of a
> driver/bicyclist/pedestrian. I've always been uncomfortable with the "if
> it looks like a motorway, then tag it as such" for a couple reasons.
> First, does it meet the standards for a motorway in terms of height
> restrictions, turn radius, restricted access, etc.
Yep, that's the question, "does it meet the standards?". It's a hard
question to answer at a glance.
> Second, over what
> distance are you going to consider the road characteristics? Part of my
> commute route follows a state highway that looks like a motorway in
> isolated sections--dual carriageway, 60 MPH, restricted access, etc.,
> but it has stoplights at grade intersections every mile or so, sometimes
> more often. Also, if you continue on the road, it peters out into a
> 2-lane highway wit h slow tourists and grinds through pedestrian-clogged
> tourist-trap towns. Not a motorway.
I would consider the characteristics over any portion of the roadway.
To use your example, and assuming that by "restricted access" you mean
"bicycles/pedestrians prohibited", I'd tag it as trunk for most of the
length (the dual carriageway/high speed section) and secondary once it
drops to two lanes.
There's no reason that a road must be tagged the same throughout its
length; the state/county -> secondary, US->primary guidelines just give
a minimum for those administrative classifications. If a highway meets
the relevant specifications it should absolutely be tagged as a
motorway, as long as you know it meets them. If it doesn't meet them,
then the physical layout of the road (dual-carriageway, possibly ramps,
etc.) as well as the speed limit tags and access restrictions give a
hint to the map user how closely this will resemble a motorway.
-Alex Mauer "hawke"
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