Drivers of tractors and other vehicles which tow or carry plant machinery on low trailers in Cornwall are being stopped to check they have a licence.
Launceston's road policing unit is carrying out the checks in the north and east of the county.
Officers said they had received reports of increases in towing in the area and wanted to ensure vehicles were safe and legal.
They will check operators' licences, driver hours and excise payment papers.
Checks will also be carried out on vehicles' fuel to ensure red diesel is not being used in any vehicle on a public highway.
Police said they would involve the Vehicle and Operator Services Agency (Vosa) and HM Revenue and Customs if any regulations had been breached.