Darrin Robinson, 23, was headed westbound on a Suzuki motorcycle when he struck the back of a Honda motorcycle operated by Altaron Robinson, 26, in Bethlehem Township around 7:20 p.m., NJSP Sgt. Philip Curry said.
The Suzuki overturned and the Honda ran off the road, ejecting both riders near mile post 8.8, Curry said.
The motorcyclists -- both of Allentown, PA -- were airlifted to St. Luke's for treatment.
The 23-year-old motorcyclist was seriously injured while the 26-year-old was moderately injured, according to Curry.
The right two lanes of Route 78 westbound were closed for approximately three hours.
Click here to follow Daily Voice Highland Lakes-Vernon and receive free news updates.