SAFETY IS PRIORITY NUMBER ONE - All Aboard: The Complete North American Train Travel Guide - page 211

Time Off
Every member of the operating crew—meaning the engineers and
conductors—has a limit to the number of on-duty hours he or
she is permitted to work. The employee is not allowed to work
for more than 12 hours, and after that he or she must break for
at least 8 hours before beginning another 12-hour shift. This rule
is strictly enforced. Once that limit is reached, an engineer or a
conductor “goes dead” and cannot continue to operate the train.
That's true even if bad weather or mechanical problems have
delayed the train so much that time runs out before it reaches a
station. In those cases, the crew must stop the train wherever it is
and wait for a new crew to be put aboard. Usually Amtrak will
have been alerted to the problem in advance by radio and will
arrange for a fresh crew to meet the train somewhere en route.
Drug Testing
Railroads have always had strict rules against the use of alcohol
or drugs, but they were self-policed. That all changed a number
of years ago when an accident occurred in Chase, Maryland. A
Conrail engineer, Ricky Gates, ran his locomotive onto the main
line and into an Amtrak train, killing a number of people. Gates
tested positive for marijuana. As a direct result, the federal gov-
ernment began pressing for a universal policy of random drug
testing. Those tests are now administered by the railroads to their
conductors, engineers, and dispatchers.
There has been an additional if somewhat ironic benefit to
come from that accident. The railroad unions and various com-
panies realized that if they didn't work closely and productively
together to find an acceptable and meaningful drug testing policy,
the federal government would probably do it for them. From this
improved relationship between the two traditional adversaries