Braintree police are investigating the cause of a late night motorcycle accident on Quincy Avenue that occurred at 11:21 p.m. on Sunday.
According to police, the operator of the motorcycle, a 53-year-old Weymouth man, suffered serious head and neck injuries. He was transported to South Shore Hospital and later transferred to Brigham and Women’s Hospital in Boston.
According to a witness, who was traveling north on Quincy Avenue in the right hand lane, the victim came up behind him and tried to change lanes in an effort to pass the witness, when he crashed onto its side.
The witness could not estimate the motorcycle’s speed.
A second witness told officers that he heard the motorcycle accelerate at a fast speed and then saw it crash onto the pavement.
The crash is under investigation by the Braintree Police Department Traffic Division.