[Tagging] Access restrictions and expressway=yes
Minh Nguyen
minh at nguyen.cincinnati.oh.us
Sat Feb 20 20:50:58 UTC 2021
Vào lúc 12:39 2021-02-20, Minh Nguyen đã viết:
> Conventionally, U.S. road maps distinguish between "expressways"
> (limited-access or partially controlled-access roads) and "freeways"
> (controlled-access roads) with a different color and/or line pattern.
> [2] (The term "limited-access" refers to the presence of abutters and
> at-grade intersections, not access keys like foot=*.) Unlike in other
> countries, the distinction between expressways and freeways is not
> consistently expressed by law or signage, and it also doesn't neatly
> align with the global highway=* definitions in OSM, especially when it
> comes to substandard roads.
>
> From a traffic engineering standpoint, an expressway differs from a
> surface street by meeting most of these criteria:
>
> * Designed for high speeds (doesn't necessarily have a high speed limit)
> * A dual carriageway
> * Frontage roads consolidate driveway access
> * A mix of ramps and at-grade intersections
>
> An expressway doesn't meet all the criteria of a freeway, for example by
> having a few signalized or unsignalized intersections with cross
> streets. An expressway may be a relic of an older time before freeways,
> a political compromise between motorist and environmental interests, or
> a surface street being gradually upgraded to a freeway in stages as
> funding allows.
I should point out that usage of highway=trunk in the U.S. is often
based on similar criteria, since there isn't an obvious definition of a
trunk road in the U.S. But we've endured years of edit wars between
ardent road classificationists because some expressways are far too
short or insignificant to be tagged as highway=trunk. expressway=* is
one approach to resolving the disagreement, but it's imperfect for other
reasons -- namely, that it lacks support from data consumers.
--
minh at nguyen.cincinnati.oh.us
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