[Talk-us] US highway classification

[Nathan Mills]

 On Fri, 27 May 2011 12:17:53 -0400, Nathan Edgars II wrote:

>> The 'major intercity' road ought to be tagged as primary unless 
>> there's
>> a specific reason to upgrade, IMO. That leaves the data more useful 
>> to
>> end users.
>
> Actually that leaves it less useful for users in cities, as then
> there are only two classifications for non-intercity highways,
> secondary and tertiary.

 Uh, what are you on about? Motorway itself doesn't necessarily imply 
 intercity or intracity, and neither do any of the other classifications. 
 I can think of several intercity county roads that ought not qualify for 
 anything beyond unclassified (they're old routes with several bypasses) 
 and several intracity routes that definitely ought to be classified as 
 trunk or motorway. It comes down to how the highway is built and what 
 the highway is.

>> Also, I don't know how major a road between Dumas, TX and Texline, 
>> TX
>> really is. If it weren't a US highway, I'd probably demote it all 
>> the
>> way to secondary.
>
> It's on the National Highway System, meaning the FHWA considers it to
> be a major road. It's probably the best route between Kansas City and
> Albuquerque.

 I'm going to assume you mean 'best non-Interstate route'. Most of it 
 isn't even four laned yet, although Texas has some of it under 
 construction. Same goes for the segment between Clayton, NM and I-25, 
 although there New Mexico is upgrading the road to four lane divided in 
 one whack. Which, as an aside, makes for one incredibly long 
 construction zone.

 Talking solely about relatively rural areas, it seems to me that by 
 default the best non-motorway route between two regionally important 
 cities should be tagged primary unless there's a reason to upgrade it to 
 trunk based on the physical characteristics of the road. To me, trunk 
 implies a divided 4 lane at worst, or arguably including a true super 2, 
 of which I've seen a couple in Kansas (I think one of Oklahoma's 
 turnpikes might also be a true super 2, but I haven't driven it 
 personally). It just makes sense to me based on the way we build our 
 roads here in the US.

 I maintain that tagging both two lane and four lane divided roads as 
 trunk (not to mention the cases where it's used for a 
 not-quite-a-motorway) makes the map much less useful for planning a 
 route at a glance. Obviously, software can take the maxspeed and lanes 
 tags into account when available but if I'm, for example, looking at 
 some rendered tiles, that information is not available.

 We already have four other tags to indicate importance in a route 
 network, so I don't see the downside to limiting trunk to roads where 
 the physical characteristics imply a higher classification, as we 
 already do with motorway.

 -wierdo