[canonuk]

I had that problem. It happens when the RGB value you used in map_t isn't quite right, and the map puts an unconnected piece of road in. When ai road piece is unconnected that's how it looks.

I haven't tried deleting those in FMB yet since I only heard about asheshouse's technique the other day, but I had to go into Photoshop/gimp and manually change the RGB value of the affected pixel. You can spot them because they're much brighter than the surrounding road/rail pixels.

Also, I've found that road and rail is able to be laid over water, but vehicles don't use them.