Which of the following types of brakes can not be checked at the depot?

The operation of the electrodynamic brake, which functions by converting kinetic energy into electrical energy, is only effective at higher speeds. Low manoeuvring speeds are required in the depot area, as confirmed by the 10 km/h speed limit sign visible in the picture. Under these conditions, it is not possible to accelerate the vehicle to a sufficient speed to reliably test this braking system.