Claude Racine was off-duty and wearing a helmet when the crash occurred late Wednesday on the turnpike's eastern spur in Jersey City.
But the 44-year-old Paramus resident suffered a serious head injury and later died at a hospital.
A female passenger was also thrown from the motorcycle and seriously injured.
But her injuries are not considered life-threatening.
Authorities say Racine was eastbound on his 2006 Harley-Davidson when the accident occurred.
But it's still not clear what caused the crash.
Racine had served for more than 10 years with the Somerville Police Department.
Colleagues there said he was known for his humor, charity work and generosity.
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