Time Pollution (John Whitelegg, 1993)

In his 1993 essay, originally published in Resurgence & Ecologist, the author tries to explain why the more people try to save time, the less time they seem to have. This is true of transportation as well, and he uses travel time as an example of this phenomenon. Regardless of what mode people chose, they tend to average the same amount of time traveling. He also points out that there is a fundamental difference between speed and access.
This is an interesting read when considering performance metrics for transportation systems.
Download a pdf of the article or read the article on-line.