Robert Magruda, 38, of Pricedale, Rostraver Township, died about 2 p.m. Thursday in Mercy Hospital, Pittsburgh, where he was flown after the accident in the city's Black Diamond section.
The Allegheny County Coroner's office ruled Magruda died from blunt force trauma, a spokeswoman for the medical examiner's office said Friday.
The manner of death is still under investigation.
The northbound Norfolk Southern engine was sounding its horn when the truck pulled into its path along a railroad crossing at the entrance to the Metals Management scrap yard, police said. The truck was carrying an empty trailer. Witnesses said Magruda apparently did not see the train.
The truck went airborne and landed against a tanker car containing more than 23,000 gallons of a molten corrosive chemical, none of which leaked.