Sudbury police arrested a man Friday morning who was found passed out drunk in his car on Highway 144 in Chelmsford.
Motorists alerted police when they witnessed the 49-year-old man's vehicle blocking traffic at an intersection near a local school.
His vehicle was moved to a nearby parking lot, and the man was taken to police headquarters, where his blood alcohol content was found to be three and a half times the legal limit.
The driver had previously been convicted of impaired driving.
He was held for a bail hearing, and was later released with a court date to answer for charges of impaired driving and blowing over .08.