Five drivers have returned positive tests for illicit drugs, following a driver testing station in Bungama yesterday.
Police and staff from the National Heavy Vehicle Regulator conducted the station on the Augusta Highway, with 605 drivers undergoing screening tests.
The five drivers were prevented from driving for 24 hours and may face further penalties following forensic analysis.
Police also issued 14 expiation notices, 16 defect notices and three expiation notices for cannabis possession.
Police and the NHVR often work together throughout the Yorke Peninsula and surrounds to monitor and enforce vehicle compliance and to spread road safety awareness.