Safety advice has been issued after a train driver was killed after being trapped between two trains.
The driver had got off a train at Tyseley Depot, in Birmingham, on 14 December and was hit on another siding.
The Rail Accident Investigation Branch (RAIB) said current safety measures may not "effectively control the risks" of walking or working in depots.
West Midlands Trains said it is cooperating with the investigation.
The urgent safety advice issued by the RAIB said the train driver had brought in an empty train and, once it had been shut down, left its cab and crossed the depot yard.
The yard, it said, had a number of sidings, one of which had two stationary trains positioned close together, which the driver tried to pass between.
The report added a second driver was in the cab of one of the trains and attempted to couple them together as the first driver was passing through, trapping him.
The RAIB said it performed a reconstruction which showed the second driver would not have been able to see the first as he crossed the yard and entered the gap.
It has advised that staff who are required to work in depots are made aware of the risk of passing between or close to the end of stationary rail vehicles and that suitable measures are put in place to control the risks, like training.
The RAIB said its full investigation into the death is ongoing.
West Midlands Trains, which runs the depot, said: "We are fully co-operating with the RAIB investigation and will follow any resulting findings and guidance."
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