>The Bay Bridge here in the SF Bay Area has had to steadily increase
>the cost of the toll
>because their efficiency went negative: it was costing them more to
>maintain the toll mechanism than they were collecting.
In 2000 they stopped collecting a toll on the bridge to the Los Angeles harbor for the same reason.
http://www.dot.ca.gov/dist07/aboutdist7/pubs/inside_seven/pdf/Feb00.pdf