Terry,
Depends how much you want to show the motion of the vehicles. This one:
http://www.worldphotographyforum.com....php?photo=303
was 20 seconds, f/16, ISO 200.
Faster shutter speed (and wider aperture) will give less movement. It costs nothing to experiment, you'll learn a lot in the process, and you'll be a better photographer for it. Tray a range of different settings. Without knowing what you want, and I don't think YOU know what you want yet, it's difficult to advise what the best settings will be.
A tripod is pretty much essential for this kind of picture.