I have seen this before. It's common problem for train crews, longhaul truckers and people who drive for long periods. It's not "sleep" per say but a fringe where one nods for a few seconds. If you have ever driven on a long trip and get that feeling of "heavy lids" and head nods. Attention is serverly reduced but still alert enough to handle those routine task like blowing for the crossings, but may not have reqonized the RED signal as his. I am not condoning the engineers condition only confirming that this does happen. This issue of having enough rest before being required to return to work has been an issue with the Unions ,Carriers, and Federal Agencies for a long time. The trucking Induistry just had it's rules changed in favor of longer rest periods this past January. This past winter on several occasions, I was working 12 or more hours (including deadheads which are counted as rest) return home for 3-4 hrours and back at work. Example: I take a train from Rochester NY to Buffalo NY, get off my train after 12hrs on duty at Buffalo and wait at the terminal for 1-2 hrs for a cab to take us back to Rochester NY. (My rest actually started when relieved of train service) Now a 2 hr Cab ride to Rochester, then about a 1/2 hr drive home. About 4 1/2 hours of my rest has been spent getting home. The Railroad can call me back on duty in 3 1/2 hrs. 3 hrs at home 1/2 hr drive back to work. Even when receiving a max. 10 hr rest after 12 hrs of duty that still only equals 5 hrs at home in a bed.
I personally would like to see a required 10 hrs rest after each work period.