Disclaimer: most of these links are now broken
Markos Papageorgiou (1991) Concise encyclopedia of traffic & transportation systems. ISBN:0-08-036203-6
Advantage: This book covers all the major (and most minor) topics on traffic and transportation systems. Depending on the topic, it lists different techniques used and gives technical designs, theories and equations for existing systems. It has an organised layout and information is easy to find.
Disadvantage: It is a little dated (10 years old) and has much information on particularly air but also sea traffic which is irrelevant for this project.
Drew, D.R. (1968) Traffic flow theory and control. New York: MacGraw-Hill
Intelligent Transport Systems:
Traffic simulation sites:
Traffic papers (that I've read)