One of the most common problems automatic train control (ATC) techs face is a ‘down track circuit(s)’. That is, a track circuit that is showing false occupancy — it looks like there is a train in that section of track when there is not. That is due to the (usually) fail-safe design of the system. Any failure — loss of power; a broken rail clamp; a bad connection; a faulty circuit board; cracked/broken rail; defective impedance bond; etc, will cause the track relay to drop and indicate that there is a train in the associated circuit (i.e. section of track).
Until recently at least, train movement took priority. If there was a down track circuit during rush hour, Central Control (OCC) generally would not let us go wayside (onto the tracks) to investigate. They were even more reluctant to do so after some employees were killed and new safety rules were implemented. The rules stated that generally ATC techs must install slow (15 mph) speed restrictions before going wayside. OCC knew that would delay trains even more than the down track circuit so they generally denied us permission to work during rush hour — even though if there was a quick fix (like replacing a broken clamp) delays would be minimized.
One day, there was a down track circuit on the outbound track (track #2) just north of the tunnel between White Flint (A12) and Twinbrook (A13). My coworkers requested that Central give them permission to go wayside and OCC refused to do so until after rush hour. When they finally were allowed to go check the wayside equipment they found a broken rail! There was about a 2″ gap at the break and trains full of passengers had been running over it for hours!
That is just one example of what the attitude used to be, and still is to a certain extent.
I recall switch problems that could have been resolved by replacing a fuse but OCC refused to give us even one minute to locate the bad fuse and replace it. Instead, their knee-jerk reaction was to have us go wayside and ‘block’ the track switches (literally putting a block of wood into the switch to prevent it from throwing). As a result, thousands of passengers were unnecessarily delayed until after rush hour when we would be allowed to resolve the problem.