Seems like a risky policy to me but maybe it is typical:
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www.nytimes.com]
"Paul Oversier, assistant general manager of operations for BART, said on Saturday that it was not yet known who was operating the train, but he confirmed that “a number of people” were on board.
Mr. Oversier said the two employees inspecting the track had “simple approval,” meaning they could work in a restricted area as long as they did not interfere with the normal operation of trains or equipment. Workers with such approval are not allowed to work directly on the track unless they are able to move to a safe location at least 15 seconds before a train moving at top speed arrives.
The maximum speed for trains where the accident occurred is 70 miles per hour, according to BART documents."