Cycling in Sydney Australia
A placemarker for Kylie's point about accessibility.
I agree paths should be compatible with the need for wheelchair riders to pass.
Additionally, I'll add to this subject catering for people who can ride bikes but who have disabilities. In particular I think there's a need for paths suitable for people with intellectual, vision and hearing limitations.
I did a stint with these guys quite a few years back now. I doubt as an organisation they will add to the campaign, but may be able to provide some insight or names.
On this topic, I know a few people here are handy with tools (and bikes) they always need volunteers to build all sorts of customised stuff.