Are you allowed to move away from the parked vehicle, if the engine is running?

In the photo you can see a lorry cab with the key in the ignition and warning lights on the dashboard - the engine is running, and there is no driver near the vehicle. While parked, you are not allowed to walk away from the vehicle if the engine is running. The answer is: no.

The Road Traffic Act directly prohibits the driver from walking away from the vehicle when the engine is running, and separately requires the driver, while parked, to protect the vehicle against being started by an unauthorised person. A running lorry left unattended is a double danger: it is enough for someone to get in and put it in gear, or for the vehicle to move off by itself on a slope if the brake is not fully applied; on top of that there are exhaust fumes and noise, which the Act also prohibits producing without need. Neither warming up the engine in winter nor running a refrigeration unit or a pump justifies this - if a device needs the engine running, the driver must stay with the vehicle. Before you walk away, even to the ticket booth in a car park, you switch off the engine, take out the key, apply the parking brake and lock the cab.

Legal basis: Art. 60 para. 2 point 1 and 2 and Art. 46 para. 5 of the Road Traffic Act (Prawo o ruchu drogowym)