[Talk-us] [Talk-us-newyork] Highway classification guidelines for New York State

[Minh Nguyen]

Vào lúc 13:55 2021-09-17, Eric Patrick đã viết:
> *If I'm not mistaken, the code you linked to is specifically a set of
> penalties for transitioning to a lower-classed road. [1][2] This is what
> I was referring to earlier as "heuristics around avoiding the use of
> *
> *lower-classed roads once you're on a higher-classed road until you get
> *
> *close to the destination". For example, each transition from a
> highway=trunk to a highway=primary penalizes the route by 40 seconds (5
> seconds with the shortest-route engine), so the routing engine would
> prefer a different route that stays on the trunk road for another 30
> seconds based on its speed limit.*
> *
> *
> Yes, but those values are assigned to the same road type within the 
> code. A trunk road isn’t going to have a value of 5 in one place and a 
> different value somewhere else. Doing that will make routing do some 
> funky things.

I'm not suggesting that a router needs to apply different heuristics for 
a highway=trunk in an urban area versus a highway=trunk in a rural area. 
Rather, I'm pointing out that Principal Arterial covers a variety of 
roads that *should* be handled differently by renderers and routers, so 
we should represent that distinction in the highway=* tags we choose. 
Assigning these roads the same tag is what would lead to funky things, 
as I have already illustrated. If the FHWA functional classification 
system doesn't help us make the distinctions that matter for our use 
case, then unfortunately we'll have to base our decisions on something else.

Function versus looks is missing the point. State DOTs invest a lot of 
effort into FHWA functional classifications, but even they don't use 
this specialized system in the official highways maps they publish for a 
lay audience. Why should this particular functional classification 
system enjoy prominent placement in the highway=* key while another, 
perhaps better suited system should go untagged?

-- 
minh at nguyen.cincinnati.oh.us