[mkgmap-dev] removal of parallel lines

Hi all, At low resolutions I would like to be able to remove parallel lines so that (for example) only a single motorway carriageway or railway track is shown instead of two or (in the case of the West Coast Main Line) four lines, which due to different Douglas Peucker line simplifications end up crossing each other, look messy and add unnecessary lines to the overview. Has anyone done this before or have any ideas about how I might go about it? Cheers, Mike