New York (CNN) -- A National Transportation Safety Board investigation has revealed new facts about the Bronx crash that killed 15 people in early March, with the head of the NTSB issuing renewed calls for changes in bus safety and regulation of bus companies. One of the primary findings of the investigation so far is that contrary to bus driver Ophadell Williams statement to authorities that a tractor-trailer may have clipped the bus causing the accident, the NTSB engineer who examined the bus found no evidence to indicate that a truck had come into contact with it, NTSB chairman Deborah Hersman told CNN.
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Fifteen people died in a Bronx bus crash in early March
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The bus was headed to Manhattan from a Connecticut casino.
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An NTSB investigation does not support the bus driver's claim that a truck clipped the bus
Investigators determined that the bus was traveling at 78 miles per hour at some point between leaving the @placeholder casino and the scene of the accident, while the speed limit at that stretch of roadway was 50 miles per hour for commercial vehicles, Hersman told CNN.