Mistakes by a Metro supervisor and a train operator are to blame for the death of a 47-year-old track worker who was hit by a train last month, according to an internal safety investigation conducted by Metro officials.

The failures were so serious that Metro has taken the unusual step of requiring about 4,000 track and operations workers to complete refresher training in safety procedures. About 100 employees have so far been retrained.

The investigation found that several Metro employees failed to follow key safety procedures Oct. 1, when Michael Waldron and fellow crew members were working along the Yellow and Blue Line tracks near the Braddock Road stop in Alexandria. The crew members were working on the inbound track, and its electric third rail had been turned off. Trains in both directions were sharing the outbound track.

Members of the crew were finishing for the day about 4 p.m. and were throwing tools from the track where they had been working over the working track to the platform, said Michael Waldron's widow, Betty. Michael Waldron was the last man on the tracks and was about to leave when he spotted a cord on the working track and bent over to pick it up, she said. He was sideswiped by a Yellow Line train, which was traveling at a normal speed of 25 to 35 mph.

He was hospitalized and died of his injuries two weeks later, the first workplace fatality at the transit agency in eight years.

The investigation found that the supervisor of Waldron's crew violated basic safety rules by failing to inform Metro's control center, which monitors all train movement, that workers were on the track bed. Because they didn't know about the crew, controllers did not warn train operators to watch out for workers on the track. The supervisor also left the work site before the rest of the crew and was not there at the time of the accident, another safety violation.

The operator of the Yellow Line train that hit Waldron also broke safety rules by failing to blow his horn when he saw the workers on the tracks, according to Metro officials. Operators are required to sound a horn when they see track workers and to stop their trains if they don't receive acknowledgement in the form of a hand signal. The operator of a second train that passed through the area after Waldron was hit also failed to blow his horn, the investigation found.

In addition, the work crew had been unsafely crossing the working track all afternoon, taking a dangerous shortcut instead of a route that would have kept them out of the way of trains, investigators found.

The supervisor, whom Metro officials would not identify, was fired last week. He had worked for Metro for 20 years. The two train operators face disciplinary action, but Metro officials would not comment further and would not answer questions about the investigation.

Metro spokeswoman Lisa Farbstein would not permit the Metro official who led the investigation, Assistant General Manager Fred Goodine, to speak publicly about the report. "We're going to let the press release speak for itself," she said. Metro Chief Executive Richard A. White was unavailable, she said.

Betty Waldron said she was unsettled by the results of the investigation. "It's just beyond comprehension," she said. "I just knew that it wasn't Michael's fault. He was always so careful about safety. . . . This is just very upsetting."

She said she had heard nothing from Metro about the investigation. "At least they could have let me know," she said. "They didn't even call me."

Waldron lived in Riverdale with his wife and their 13-year-old son and had worked with Metro's track and structures department since 2002. Betty Waldron said she wants more details about why her husband died. "I would have more closure if I knew what happened, that my husband wasn't at fault and that someone has been reprehended for the fault," she said. "We're not at peace. We're having a very difficult time."

Safety procedures around track work are especially important because Metro is performing an increasing amount of work midday and on weekends, when trains are running.