Are you looking to open your transportation agency's data?
Getting Started with Open Data provides the how-to, why-to, and other useful resources for opening transportation and related data. The guide was spearheaded by Sarah M. Kaufman at the NYU Rudin Center for Transportation Policy and Management. OpenPlans Transportation's Jeff Maki contributed to the effort
The guide answers the questions that will arise during the process of opening data: How do you open data? Why does it need to be maintained? What potential obstacles and liabilities are there? And how does the developer community develop around the datasets released?
You can find the pdf here.