[mkgmap-dev] no_u_turn

Sun Oct 4 18:48:19 BST 2009

>>
>> I feel it's only fair to mention that some of these no_u_turn
>> restrictions are flagged as invalid by JOSM but that is because it
>> (wrongly in my opinion) seems to take the direction of the via way into
>> account.
> 
> Our implementation of turn restrictions does not handle via ways, only
> via points.
> 

Can I make this a feature request then? :) Consider the following

A       B       C
--------+------->
        |
<-------+--------
D      E|       F
        |
        \/
        G
ABC is oneway in direction ABC
FED is oneway in direction FED
BE is twoway but is marked with direction BE

U turns are not allowed for FEBC nor are they allowed for ABED

I have several of these near me and I'm sure they're fairly common (if
not yet in the OSM database). Current mkgmap maps will tell me to make a
U turn (FEBC or ABED)

Cheers

Paul