The Virgin East Coast driver sheltered next to his cab just three seconds before the high-speed train passed.
The 3 August incident happened 12 miles (19.7km) north of York station.
A report said it was the result of a lack of "clear understanding" between the driver and a trainee signaller over whether a line blockage was in place.
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The Rail Accident Investigation Branch report said the driver was attempting to carry out tests on the 07.55 BST Inverness to London King's Cross train when it experienced a loss of power at Kyle Beck, near Tollerton.
It said the driver contacted the signaller - a trainee working under the guidance of an experienced colleague - to request trains on the adjacent lines be stopped in order to carry out the checks.
After communicating the request, the signaller said he would call the driver back to confirm the line blockage.
But, the report found, the driver stepped down from his cab before receiving the confirmation.
A CCTV image taken from the front of the passing train showed the driver sheltering next to his vehicle. The driver was unhurt.
"It is possible the driver may not have heard what the trainee signaller said or that he had misunderstood what he was being told," the report said.
"The driver and the trainee signaller did not reach a clear understanding about stopping trains on the adjacent lines and the driver subsequently alighted from the driving cab of his train, incorrectly believing it was safe to do so."
A train driver narrowly avoided being hit by a second train travelling at 105mph (169km/h) when he was investigating a power failure.