One path for the shape, offset that path twice to make 3 tracks, then use multiple stroke styles? Nice! Did you place the numbers manually?
One Illustrator holygrail trick I haven't figured out how to do yet is to have a path with multiple stroke styles but also with text along it. It would be awesomely useful for street maps. If Illustrator had anything like 3DSmax's instanced geometry, it'd be simple (if if if).