BILL HEMMER, CNN ANCHOR: Engineers trying to figure out what caused a pedestrian walkway collapse in North Carolina have found some clues there. They're focusing on steel reinforcement within the concrete girders. The accident occurred as fans were leaving late Saturday night from a Nascar race in Concord, North Carolina. More than 100 people were injured on the ground there. And from the ground, here is CNN's Brian Cabell with more.</s>BRIAN CABELL, CNN CORRESPONDENT (voice-over): What caused the sudden collapse of the pedestrian bridge? One government engineer has a possible answer.</s>DON IDOL, N.C. DEPT. OF TRANSPORTATION: I did observe some of what appeared to be corrosion of some of the pre-stressing strands.</s>CABELL: In other words, the structural support of the bridge may have been weakened. Engineers will continue to investigate the cause as the debris is cleared. Inspections are required on bridges like this every two years. The president of the speedway, which also owns the bridge, says he's not certain when the structure was last inspected. The bridge collapsed Saturday night, shortly after the race ended. Witnesses said pedestrians were shoulder to shoulder on the almost 20-foot high bridge when it suddenly cracked without warning. Chris hill, who suffered a gash on his head, was one of the victims.</s>CHRIS HILL, VICTIM: Just like any bridge you go over any day or any walkway so, I mean, do you ever give it a second thought?</s>CABELL: His daughter Carissa suffered some scrapes in the fall. His father Jim fared worse, a broken ankle.</s>UNIDENTIFIED MALE: I came through it pretty good considering a lot of other people that I was looking at laying there in that pile.</s>CABELL: Engineers are also inspecting a second footbridge to the race track, checking there for any sign of weakness. (on camera): As for the racetrack itself, its schedule will continue unchanged. Qualifying for the next race is on Wednesday. The two footbridges will not be used. Brian Cabell, CNN, Concord, North Carolina.
North Carolina Investigators Focus on Steel Reinforcement as Cause for Pedestrian Bridge Collapse