Lorry and van drivers were caught committing a catalogue of offences, including speeding, driving without care and attention, and using mobile phones during a covert police crackdown.
Police in Norfolk and Suffolk spotted more than 300 offences in a week after stopping 250 heavy goods vehicles and smaller vehicles, including vans.
The catalogue of crimes shocked Norfolk's police and crime commissioner Lorne Green, who said the drivers flouting the law had put their lives - and those of others - at risk on the region's roads.
Other offences discovered during the week-long Operation Tramline - which saw drivers pulled over on the A11, A47, A12 and A14 - included insecure loads, ignoring red lights and not being in proper control of their vehicles.
Police were lent an HGV tractor unit by Highways England, which meant officers could peer into cabs of other lorry drivers or down at cars or vans.
Just under 250 vehicles were stopped, including 135 HGVs and 86 smaller goods vehicles, with 307 offences recorded. Some drivers committed more than one.
Police issued 256 Traffic Offence Reports, which could lead to drivers being taken to court, given a fixed penalty notice or told to attend a driver education course.
The offences were:
165 for not wearing a seatbelt
55 for construction and use (that includes the maintenance and condition of the vehicle)
28 for using a mobile phone
25 for an insecure load
12 for not being in proper control of the vehicle
Nine for driving without due care and attention for excess speed
Five for excess speed
Eight for other offences, including driver hours and driving through a red light
Mr Green said: "For the drivers to be committing offences that put the lives of themselves and others at risk is unacceptable and this is no different for HGV drivers transporting goods around our county.
"It is disappointing to see the volume of offences committed during this short period of time, which in itself demonstrates how valuable operations such as Tramline are.
"There is simply no excuse for flouting the law and I want to send a strong message to drivers of all vehicles that Norfolk will not tolerate careless driving and behaviour that puts any driver and other road users around them at risk.”
Operation Tramline took place between Monday, March 8 and Friday, March 12.
Sergeant Scott Lee-Amies, of the Norfolk and Suffolk Roads and Armed Policing team, said: "The HGV cab provides officers with an ideal vantage point to spot drivers committing offences and provides us with another means to enforce the law with this specific group of road users, who, due to the size of the vehicles they are in control of, pose an added risk to other motorists and also themselves if they are committing offences whilst driving.”
A spokesperson at one Norfolk haulage company, who did not want to be named, said none of their drivers had been pulled over in the operation.
But they said: "We do take infringements very seriously. Everyone who commits an infringement is spoken to and if they do it again, it would be taken further."
The results of the crackdown come in the same week that a lorry driver was sentenced for causing death by careless driving on the A11 near Wymondham.
Paul Eadle, 50, of Sycamore Avenue, Wymondham, admitted causing the death of Costessey man Rikki Loades by careless driving.
Mr Loades and another driver had stopped next to the A11 near Wymondham after they were involved in a crash with a deer.
Norwich Crown Court heard they were examining the damage when Mr Loades was struck by a lorry being driven by Eadle.
Father-of-two Mr Loades died at the scene of the crash on April 29, 2019.
Eadle was sentenced to six months in prison, suspended for 12 months.
He was also ordered to do 300 hours unpaid work and banned from driving for two years.
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