[OSM-talk] Advanced highway tagging

[Dair Grant]

Simon Hewison wrote:

>Okay, so one of them (A26) is an autoroute péage, and one 
>(A16) doesn't charge a toll. The distinction is obviously there 
>in the underlying Tele Atlas database; and someone at Google 
>decided to render a french autoroute péage in a darker orange 
>than non-péage.

If you google for "multinet shapefile format specification" 
you'll find the spec for the data Google use. Page 19 documents 
the "network table", which is the road/ferry layer.

I have written a renderer that uses TeleAtlas data to produce 
very similar results to Google Maps, and I strongly suspect 
their appearance is driven purely by the FRC value (the 
"functional road class", an integer from 0 to 8 that classifies 
roads by "importance").


The TA approach is to provide two descriptions of "road type" - 
one for rendering (FRC), and one for routing (NET2CLASS).

The routing hierarchy roughly follows the FRC classification, 
but allows local roads to be promoted when they're important for connectivity.


It might be useful for OSM to take a similar approach, 
separating the "importance" of a road (for either rendering or 
routing) from its legal status/surface 
characteristics/country-specific classifications.

The highway tag is a bit of mixture at present: importance 
(motorway/trunk), surface (unsurfaced/track), or legal (bridleway/cycleway).


-dair
___________________________________________________
dair at refnum.com              http://www.refnum.com/