Safety laws suggest that wheel chocks are essential for every commercial vehicle. Wheel chocks are used to stop vehicles from rolling when they are parked – especially on a hill. It is extremely dangerous when the brakes give way on a large commercial vehicle, potentially damaging anything that gets in its way. Even a small slope, or uneven ground can result in your vehicle rolling - so be prepared!
For more information on this check out https://worksafe.govt.nz/about-us/news-and-media/driveshaft-parking-brake-failures-in-commercial-and-industrial-vehicles/