The day after a deadly D.C. metro train wreck, the entire system was operating on "manual," according to an AP report (via Forbes). This precaution, according to reporters Karush and Westley, was being taken because the train that probably caused the crash was in "automatic mode" at the time of the accident. According to the report, this means that the train "was controlled primarily by computer."
The report doesn't clarify whether the issue may have been software, impaired sensor signalling or faulty wiring. Computerworld's Patrick Thibodeau pointed out that the software in question was specifically designed to avoid rear end collisions. Possible computer-related causes could include incorrect configurations, security breaches, human error in interacting with the system, or hardware failure. Thibodeau does not mention whether the introduction of such automated systems reduced the incidence of rear end collisions and near-collisions.