A teenager was injured while subway surfing in Brooklyn on Thursday, cops said. The 14-year-old boy fell from the top of a southbound B train as it sped past the Ave. J stop near. E. 16th St. in Midwood around 4:12 p.m., cops said. The teen landed on the roadbed as the express train — which does n ot make stops at the Ave. J station — continued down the line, an MTA employee said. “He was on the tracks, bleeding,” said the transit worker. “When they brought him down on the stretcher, he wasn’t moving. He’s lucky to be alive.” Medics rushed the youngster suffering lacerations to his head, leg and arms to Maimonides Medical Center in stable condition, police said. An MTA employee was working at the station when a group of school kids alerted her to the injured teen. Full train service was restored to the southbound B, Q lines at 5:25 p.m., an MTA spokesperson said. The teen’s misadventure in Brooklyn follows two girls who died while subway surfing atop a Queens-bound J train as it rumbled over the Williamsburg Bridge on Oct. 4. The two girls, including 12-year-old Zemfira Mukhtarov, were found sprawled out on top of the last car of a J train after it entered the Marcy Ave. subway stop at Broadway around 3:10 a.m. Each of the girls suffered a head injury and died on the train, cops said. ...read more read less