[Talk-us] Freeway directions
steveaOSM at softworkers.com
Sat Oct 19 09:05:33 UTC 2013
>On Thu, Oct 17, 2013 at 3:39 PM, Brad Neuhauser
><<mailto:brad.neuhauser at gmail.com>brad.neuhauser at gmail.com> wrote:
>"In the numbering scheme, east-west highways are assigned even
>numbers and north-south highways are assigned odd numbers. Odd route
>numbers increase from west to east, and even-numbered routes
>increase from south to north (to avoid confusion with the U.S.
>Highways, which increase from east to west and north to south),
>though there are exceptions to both principles in several locations."
>Field signage is sometimes inconsistent with the official rules; for
>example, US 68 is mostly (entirely?) signed north-south, and I-69
>becomes east-west between Lansing and Port Huron. States may have
>their own rules; some states (MS, FL) follow the even-odd rules that
>the national routes do, some use an opposite pattern (even N-S, odd
>E-W), and some have no pattern at all (GA, TN).
>There are also cases of signage by loop nesting ("inner"
>clockwise/"outer" counterclockwise for RHD) - I-495 around
>Washington and I-440 around Raleigh NC are examples, along with GA
>10 Loop around Athens GA. And in Canada the QEW is "directionally"
>signed by destination (Toronto on the clockwise carriageway, Niagara
>and then Fort Erie on the counterclockwise one). There may be a few
>more oddballs I've missed.
>IMO preferred practice should be a relation for each continuous
>cardinal direction, to keep validation simple; undivided roads
>should use forward/backward roles to distinguish which relation
>applies to the underlying way's forward/backward traversal. It
>shouldn't be too terribly hard to come up with an algorithm to fixup
>the existing single-relation cases, particularly for the ones where
>the routes are entirely dual carriageway, although occasionally the
>heuristics will be wrong and need a manual edit.
Well said, Chris. +1, lands right in the middle of where it might, imho.
Manual edits on exceptional cases means that somebody, somewhere is
paying attention. In a big set, with careful management, that's to
be expected. Good show.
Encore, author. This is a serious project which aims to accurately
map "what is." Nice job so far, everybody. I very much like this
crowd-sourced map. It only keeps getting better and better.
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