Not sure what is meant by a "disjointed" section..my guess is the joint came apart...which probably means somehow the bolts came out or a section of rail at the weld failed. The other possibility is that the track was "out of guage" possibly from spikes being pulled (on traditional wooden ties). Running a motor car over the section of track during the daylight is the norm for track inspections. Any track carrying passengers vs freight is subject to much greater inspections (at least in theory). As far as running an inspection train ...xraying welds or Magna fluxing rail..I doubt it is done very often...certainly not once a day or between trains.. As Forrest Gump said..." It happens".....
As far as running an inspection train ...xraying welds or Magna fluxing rail..I doubt it is done very often...certainly not once a day or between trains.. As Forrest Gump said..." It happens"..... My thinking was that if one records the vibrations produced by imperfections in the track every time a train passes over, and compares them day-to-day, it may be possible to detect anomolies before they cause catastrophic failures. With proper software, the effect would be that every time a train went over a stretch of track it would be somewhat "inspected" without extra labor being required. Of course, more detailed inspections should be done periodically as well, but useful trains run over the rails much more frequently than inspectors.