Miranda Warning System: CHELMSFORD — Chief Colin Spence reports that the Chelmsford Police Department Crash Reconstruction Unit is investigating a crash that caused serious injuries to a driver, and investigators are seeking to speak with witnesses. On Tuesday, Aug. 26, at 7:01 p.m., the Chelmsford Police and Fire Departments were called to Princeton Street at North Road for a report of a crash. First responders arrived to discover a single-vehicle crash in which a vehicle struck a sign in the median and then a utility pole along the road. First responders provided on-scene treatment to a seriously injured driver, a 53-year-old Chelsea man. The driver was taken by ambulance to Lowell General Hospital and then flown by medical helicopter to Boston Medical Center. The Chelmsford Police Crash Reconstruction Unit is investigating the crash. Investigators are seeking to speak with anyone who witnessed the crash or the vehicle, a green Subaru Outback, being operated beforehand. They are also asking home and business owners in the area to check their surveillance cameras for footage of the crash or the vehicle. Anyone with information is asked to call Sgt. Matthew Fernald at 978-256-2521 x301, or email mfernald@chelmsfordma.gov