[OSM-newbies] Intersection tagging redux

[James Ewen]

Okay, I'm still pondering how to tag this intersection properly. The
road network data has been imported from GeoBase, but I feel that the
ways depicting the intersection are not accurate.

The main N/S roadway is a dual carriageway, two lanes each, with
decelleration/accelleration lanes added on the right on either side of
the intersection. There is also a left turn lane added, making the
roadway 4 lanes wide at the intersection. The right hand lanes have
islands, so they should get a separate way around the corner in my
mind. The left hand turn lanes are not separate so I would choose to
not show them as a different way.

The E/W roadways have decorative planters separating the ways as they
approach the intersection, with a single lane each way. However
through traffic is not allowed straight across the intersection. This
restriction is enforced by concrete islands that direct traffic flow.

The GeoBase depiction shows the N/S left turn lanes as separate ways.
The forced left turn lanes on the E/W roadway are depicted as well,
but these 4 turn lanes share 4 common nodes, creating a diamond in the
middle of the intersection.

Would a routing engine possibly mistake these common nodes as a valid
routing choice, and try to get people to follow the routing in an
obviously incorrect manner? Should these ways cross each other without
common nodes? By not having a common node, there would be no way for a
routing engine to make a mistake. These ways do indeed all cross at
the exact same physical level on the pavement, with no grade
separation, but it is not legal to change from one way to another at
that point.


Here's the current OSM depiction.
http://www.openstreetmap.org/?lat=53.53393&lon=-113.26316&zoom=20

Here's a satellite view from Google just for visualization.
http://tinyurl.com/yjmo6o2

Here's a Google Streetview of the intersection.
http://tinyurl.com/y9b7qa2

(gotta love Streetview! Just got it for our area within the last week,
hence the redux)

BTW, GoogleMaps doesn't show the turn restrictions either... I want
OSM to show it properly.

James
VE6SRV