I read the original Cornell paper which attempted show the effect of security measures on demand for air travel (http://dyson.cornell.edu/faculty_sites/gb78/wp/

I read the original Cornell paper which attempted show the effect of security measures on demand for air travel (http://dyson.cornell.edu/faculty_sites/gb78/wp/airport_security_022305.pdf http://dyson.cornell.edu/faculty_sites/gb78/wp/airport_secur...), and frankly I didn't find it very compelling. But even were one to accept its conclusion that security measures (and not an economic downturn or a change in preference due to a percieved risk) caused the change in demand, no one presents any evidence that the air travel was replced with car travel. It seems quite likely that many trips would have been simply forgone, or along the BOS-NY-WAS corridor replaced with the train.