[Talk-us] US Trunk road tagging

[Minh Nguyen]

Vào lúc 15:03 2021-05-05, Evin Fairchild đã viết:
> On Wed, May 5, 2021, 1:41 PM Minh Nguyen 
> <minh at nguyen.cincinnati.oh.us 
> <mailto:minh at nguyen.cincinnati.oh.us>> wrote:
> 
>     For sure, this would be more reasonable than tagging the whole NHS as
>     trunk. How different would it be from basing trunk on Other Principal
>     Arterials instead? That would simplify the decision tree further and
>     make it more reliable. We already have a hard enough time maintaining
>     state route relations as state routes get realigned and redesignated.
>     For all of the difficulties this community had dealing with NE2, that
>     was one thing they did quite reliably that has been hard to keep up
>     over
>     the years.
> 
> 
> Your idea of using the Other Principal Arterial functional class seems 
> appealing. Do you know if there is a map showing all the functional 
> classes for the entire US like there is with NHS routes? All I've been 
> able to find when I googled it was just maps for individual states. It 
> would be nice if we could all take a look at it to [compare] it with NHS.

I was referring to the Other Principal Arterial class within the NHS, 
which is basically all the roads marked in red in the NHS maps you 
linked to. [1] It seems comparable to FHWA's Other Principal Arterial 
class in some cities I've spot-checked, but I don't know if that's a 
reliable assumption.

I'm still not convinced that either NHS or FHWA is a good primary source 
for highway=trunk, but it's better than potentially including intermodal 
corridors that happen to be Texas Farm to Market Roads or Missouri 
supplemental routes and better than tying road classification to state 
route data that may be outdated in some cases.

FHWA's Highway Performance Monitoring System includes functional 
classifications and is available in shapefile format. [2] However, you 
can also trust the state DOTs' maps. Each state DOT is responsible for 
classifying their roads, other than the ones that are part of national 
systems, based on the detailed guidelines set out by FHWA. FHWA then 
approves the maps.

[1] https://www.fhwa.dot.gov/planning/national_highway_system/nhs_maps/
[2] https://www.fhwa.dot.gov/policyinformation/hpms.cfm

-- 
minh at nguyen.cincinnati.oh.us