A 27-year-old District man was seriously injured yesterday when he vaulted a turnstile at the Benning Road Metrorail station, lost his footing and toppled over a parapet at the mezzanine level onto the tracks below, Metro officials reported.

They said the man, identified as Roger E. Davis, of 307 50th St. NE, fell about 25 feet. He was admitted to D.C. General Hospital, where he was listed in serious condition with head injuries, a hospital spokeswoman said.

Metro spokeswoman Beverly Silverberg said that a man entered the station near Benning Road and East Capitol Street about 6:40 a.m. and, according to witnesses, jumped over a turnstile near a waist-high concrete parapet.

But, Silverberg said, he lost his balance and tumbled onto the westbound Blue Line tracks. He did not contact the live third rail, with its 750 volts of electricity, and there was no train in the area at the time, she said.

A station attendant turned off power on the tracks where the man fell, Silverberg said, and inbound trains were rerouted briefly to the other side of the platform. Trains alternated their stops at the station along a single track while the man was removed by fire department ambulance personnel.