Nearly one in ten of the truck drivers monitored during a police operation in North Yorkshire were committing a road offence.
Using an un-liveried truck, North Yorkshire Police officers drove alongside HGVs on the A1, A168 and A19, and used a camcorder to record driver behaviour last month.
Almost 1,000 HGVs were tracked as part of the scheme, dubbed Operation Marathon, and 86 offences recorded.
Most were distraction offences where the driver was not paying due care and attention to the road because they were also on the phone. Poor lane behaviour, dangerous parking and failure to use seat belts were also recorded.
The force is aiming to reduce the number of serious and fatal accidents in North Yorkshire, where last year more than 2,800 people were injured in road collisions.