The General Accounting Office reports to Congress. It produced a report on y2k on April 30. In this report, which lists pages of vulnerable government systems, this brief paragraph appeared:
"Another risk associated with the transportation sector was described by the Federal Highway Administration which stated that highway safety could be severely compromised because of potential Year 2000 problems in operational transportation systems. For example, date dependent signal timing patterns could be incorrectly implemented at highway intersections if traffic signal systems run by state and local governments do not process four-digit years correctly."
I have only two words to add to this warning: