[mkgmap-dev] [PATCH v2] Advanced restrictions

Fri May 14 16:51:21 BST 2010

> What are via ways in restrictions? Could you give some practical example 
> of what they do and what they are needed for?
>
> Would they increase the maximal routing distance? Or maybe it the fact 
> that they are missing the reason for our intertilerouting in Mapsource 
> which is not working correctly?
>
>   
This is something I brought up a while ago. 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 but all other turn are allowed

In this situation the "via way" is BE and you create a no_u_turn trstriction from FE, to BC, via BE. Up until now mkgmap would ignore this restriction as it couldn't handle it.

There are loads of these near me and I suspect in many other places as well

Cheers

Paul