Worker fatigue from too much overtime has been a concern at transit agencies nationwide after major accidents.

In 2004, when a Metro train operator crashed into a train at Woodley Park station, injuring 20 riders, safety investigators blamed a lack of sleep.

The operator was working an overtime shift at the time, his 10th out of the previous 19 work days. In response the National Transportation Safety Board called for requirements to ensure adequate time off between shifts of work.

But the transit industry has primarily focused on making sure train and bus operators get enough rest time between shifts, not the other workers who make the system run.

Metro train operators, for example, must have eight hours off every 24 hours.

Even so, the Tri-State Oversight Committee charged with monitoring Metro's safety has tried to increase the required rest time for train operators so they can actually get eight hours of sleep, not just eight hours off between one shift and the next.

But TOC Chairman Matt Bassett said the transit agency has not been able to successfully negotiate more time with the operators union.