[OSM-talk] How do bridges work?

[Tom Hughes]

In message <E1Ii8I4-0002tE-Sp at streetmap.vm.bytemark.co.uk>
        Rick Collins <gnuarm.2006 at arius.com> wrote:

> Yesterday when I was viewing this section, I could actually see lines 
> drawn to indicate the ends of the bridges.  Now I see nothing like 
> that and even the bridges that look ok can't be distinguished from 
> intersections.

Only the tiles at home layer draws the bridge symbols - the mapnik layer
just draws the roads crossing (but stacked correctly where you can
tell the difference).

> I used a "bridge" = "yes" tag on all of the sections that should be 
> passing on top.  They were not displaying correctly so yesterday I 
> added a "layer" = "+1" tag to each of them.  This looks worse now 
> than it did before I changed it.
>
> Am I still doing it wrong?  How do I get bridges to display correctly?

Add bridge=yes (only use by tiles at home currently) and use layer
tags to indicate the correct relative ordering of the roads. So
normally the road on the bridge is layer=1. Complex interchanges
may need layer=2 etc to get everything stacked right.

Tom

-- 
Tom Hughes (tom at compton.nu)
http://www.compton.nu/