It's a good example of how humans are very bad at things that automatic equipment does well. This is a junction point between catenary and self-powered rail, so the staff are accustomed to changing locos and can do it in a few minutes, ample time not to have to worry about losing air. But here the signal problem tied the train up for 45 minutes, and the staff were so distracted by the signal problem that they forgot how much time had passed. A bit like the airline pilots who got distracted by their computer (they say) and flew past Minneapolis.