(CNN)-Only four of the nation’s 41 rail systems required to implement lifesaving technology to prevent train accidents met Monday’s deadline, according to the Department of Transportation.
The others — including Amtrak — have either applied for or been granted extensions of the deadline.
The technology, called positive train control, can prevent collisions and derailments. It involves installing equipment on locomotives and tracks that communicates information about the train’s speed as well as the position of the train and track switches.