Flashing warning lights at the crossing illuminated 39 seconds before the crash, and the gates came down a few seconds later, Sumwalt said. That would leave about 30 seconds that the SUV was inside the gates.
    Investigators haven't found any problems with the warning signals or the nearby traffic lights, which are synched to let drivers clear the crossing when a train is coming, Sumwalt said. The crossing also had painted warnings on its pavement, and a sign 65 feet from the rail warns drivers not to stop on the tracks, he noted.
    The agency hasn't mapped out how far before the crossing the engineer hit the emergency brakes on the train, which takes about 950 feet and 30 seconds to stop, Sumwalt said.
    After the impact, flames enveloped the SUV and part of the train, and the electrified third rail pierced them. Hundreds of passengers scrambled through spreading smoke and fear, some helping each other to escape despite their own injuries.
    Trains hit cars on the tracks many times a year, but such crashes rarely kill train riders. Investigators have emphasized that they want to figure out why this one did, becoming the deadliest accident in the 32-year history of one of the nation's busiest commuter railroads.
    Investigators are looking for any elements that may have intensified the fire, which they believe was ignited by the SUV's gas tank. The NTSB has been examining such factors as the adequacy of emergency exits, the crashworthiness of the train cars and the unusual design of the Metro-North line's third rail.
    The agency also is looking into how familiar the SUV driver was with her car and her route, whether she was using a cellphone and whether the backed-up traffic played a role.
    Passengers returned, some with hesitation, as service resumed Thursday on the line where the crash happened, after workers rebuilt about 500 feet of the third rail.
    Julie Garla was feeling "very lucky and still a little scared" as she rode the Harlem Line. But since the passengers who died were in the first car, she's no longer going to sit there, she said.
    But Bill Peterson is.
    "I believe the Lord's going to protect me," he said, and "the chances of it happening again are probably tiny."