It is these days.
Apparently a switch that should have been closed, allowing the train moving down the single track to pass the other train sitting in the siding, was left open, thus directing the moving train into the occupied siding and hitting the sitting train. The question is why was this switch open. From what I've just read, this happened on a rail line that doesn't have signals. Instead they are given verbal permission by a dispatcher to write down authority to occupy pieces of track, which they then repeat to the dispatcher to confirm accuracy. Part of this system confers responsibility for switch position. The system works fine as long as everybody follows the rules, pays attention, and doesn't make a mistake.
Unfortunately, without signals(which show track occupancy) and other sensors that show switch position and allow the dispatcher to control the switch, there aren't backup safeguards if someone does make a mistake. Now add in the factor that the railroads are allowed to work many of their employees on a system that doesn't allow for a regular sleep cycle. You can be called to work at 3am, work until 2pm, called back at 8pm to report at 10pm, work until 9:59am, called again at 4pm to report at 6pm, work until 5:30am, called again at 11:30 for 1:30pm, off early at 5pm (but you can't fall asleep), called at 11pm for 1am, work until 1pm, on and on and on. Many of these guys are walking zombies, and crew fatigue is one of the most prevalent factors in railroad accidents. Huge issues that has been allowed to go unrepaired. So the most likely cause is simply crew error, someone reported in the clear in the siding without closing the switch (though not necessarily the crews in the wreck, could have been a prior crew.)
But there have also been cases of tampering with switches by kids or vandals, and it is even possible that it was an act of terrorism, but the latter is very, very, very unlikely given the remote location and relatively sparse population. There are safeguards to prevent unauthorized movements of switches by persons other than railroad workers.
These types of wrecks have happened before, ever since railroads were invented.
I did accident investigation for the old Southern RR, but mostly in the Atlanta metro area . . . and everything here is signalled out the wazoo, if anything there's a chance of confusion because of too MANY signals.
I guess they can't afford to do every siding on the entire main line, but surely the major ones . . . ?!?!?
Thanks for that good explanation.
I don't think there is anything related to terrorism here but it must be SOP to call in the FBI, although local media says they don't have an answer why this was done.