It happened in the area of the Route 412 interchange in Lower Saucon Township, near the border with Bethlehem.
State police say a driver was merging onto I-78 westbound from the Route 412 ramp when he crossed both lanes of traffic and hit the truck. The truck then veered off into the median and through a guard rail.
The truck then went into the eastbound lane, hitting and killing a motorcyclist, a 53-year-old Bethlehem man.
The view from Chopper 6 HD showed the motorcycle wedged under the front of the tractor trailer.
Meanwhile, three other cars were involved in a crash in the backlog.
The flatbed tractor trailer involved stopped in the opposite side of the highway, facing oncoming traffic.
The roadway was completely reopened by 8:00 p.m.
This comes after a tractor trailer driver from Easton, Pa. was killed in a fiery crash that closed the eastbound lanes of Interstate 78 in Northampton County for nearly 11 hours Thursday.
Mario Chacon, a father of five children, died when he got out of his broken-down truck and was struck by a car.