A SNCB passenger train collided with the back of a freight train, killing three.
http://www.theguardian.com/world/2016/jun/06/belgium-train-crash-dead-injured-passenger-freight
The first of hundreds of unanswered questions - what kind of traffic control system was in place for a Passenger Train operating at 55 MPH to run into the back of a freight train.
Amazing how little information about this incident has been made available through the worlds news sources.
http://www.nbcnews.com/news/photo/high-speed-passenger-train-slams-freight-train-belgium-n586651
Based on that news story, very possibly none.
Of course, that begs the question - were signals somehow stuck showing green (or maybe amber), or were they dark?
Current speculation involves a lightening strike rendering the signals inoperative.
Which raises an even bigger question about operating practices over there. In the US a Dark or otherwise inoperative signal is to be acted up as displaying it’s most restrictive indication - in the US that is normally Restricting at a Intermediate Signal and Stop at a Absolute Signal. Nowhere in the US would a train be authorized to operate at 60 MPH with an inoperative signal system.
Taking a signal system out of service account damages from Mom Nature is a BIG DEAL and causes another Operating System to be placed in effect - a system that crews that operate in normally signalled territory are very wary of because they aren’t used to the rule set that gets placed into effect.
Rereading reports indicates that the signal problem was apparently resolved before the crash occurred. The questions that follow are if the problem was actually entirely resolved (false indication?), if the engineer switched back to normal operations as planned or not, or if the lightning had anything at all to do with the accident. Certainly seems like a SPAD of some sort.
Video associated with this BBC report seems to show that the passenger equipment had much more structural integrety than the freight equipment.
According to a local source,
the train acknowledged a restricting signal of some sort but did not begin braking before the freight train was in sight, according to the event recorder.