Jovani Julio Diaz, 28, was pronounced dead at 5:45 a.m. after being struck by the tractor-trailer on the westbound side at mile marker 45.1 in Weisenberg Township around 5 a.m., the coroner's office said.
The manner of death was not revealed.
The incident caused hours-long road closures on I-78 westbound Thursday morning, authorities said.
The investigation was being led by Pennsylvania State Police Fogelsville Barracks and the Lehigh County coroner's office.
Click here to follow Daily Voice Lower Merion-Narberth and receive free news updates.