Transport colours

I'll answer the second part of the question, since I've been asked a few times about it.

There are three issues with supporting route colours:

• There's currently no support within mapnik for taking line colours from the database. This is the main reason that it's not done at the moment, since without this support I would need to write a separate rule for every possible colour! There is ongoing work on this in mapnik, so perhaps it will be possible in 2014. See #828 and the expr-v2 branch in the code.
• It's likely to make the map a complete mess of nasty colours! The people who design route diagrams work in isolation from one another, and even within one transport area often choose lurid and clashing colours for the routes.
• I haven't figured out how to show the colours of overlapping routes in an automated fashion.

Each issue has a solution, namely:

• Patience, since things seem to be progressing with mapnik!
• I'm considering approaches to showing the colours beyond just changing the line colour, so that it's useful to viewers without overwhelming them, and also to providing different versions of the transport layer for different sites.
• This still needs an automated approach figuring out! Yvecai currently creates good results on opensnowmap, but that's by manually choosing the line offsets for every overlapping ski route. With things like buses - there are 14 different routes at my nearest stop - I don't think that this approach is yet a complete solution.