Duties of the COSS: Making sure the line is blocked, agreeing arrangements with the signaller or ES, and moving a trolley over level crossings, under GERT8000-HB10.Person in charge of the trolley: Brake tests, loading, gradients, the number of people needed, and the red light.Safe use of trolleys: Walking pace, pushing limits, conductor rail areas, failed brake tests, and leaving a trolley unattended, under Network Rail module P514.