[Talk-us] US Trunk road tagging

[Minh Nguyen]

Vào lúc 12:53 2021-05-06, Zeke Farwell đã viết:
> On Thu, May 6, 2021, 3:25 PM Minh Nguyen 
> <minh at nguyen.cincinnati.oh.us 
> <mailto:minh at nguyen.cincinnati.oh.us>> wrote:
> 
> 
>     In traffic engineering jargon, "freeway" refers to a controlled-access
>     divided highway, while "expressway" refers to a limited-access divided
>     highway or sometimes a controlled-access undivided highway ("super
>     two").
> 
> 
> Minh, can you further explain the distinction between "limited-access" 
> and "controlled-access"?  To me these terms seem synonymous.

As I understand it from a North American point of view:

Controlled-access highway:

* No abutters or driveways
* No at-grade intersections
* Typically divided

Limited-access (also known as partially controlled-access):

* No direct abutters, but there may be shared driveways few and far between
* Often divided
* At least some at-grade intersections, whether signalized or 
unsignalized; however, there may also be some grade-separated 
interchanges with ramps

(The last point is a frequent source of conflict, where a mapper 
exuberantly upgrades a very short, isolated section to highway=motorway 
right around the one grade-separated interchange, even though it isn't 
conceived of as part of a longer project to upgrade the road to 
Interstate standards.)

-- 
minh at nguyen.cincinnati.oh.us