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Living in Virginia, I have encountered some small problems regarding public transportation and accessibility. Not only is it a hard to find door to door service, but I am limited by the bus routes and city limits. Several months ago, I was talking to a friend regarding bus trainers where she lives. These are individuals who travel with you, teaching you the in and outs of the bus system. I found the idea quite compelling and so I did some research. Here is another article regarding bus trainers.. I don't know how easy they are to find or whether they're available in all areas.
http://www.disabilityscoop.com/2010/06/28/bus-trainers/9210/