the secondary braking system shall make it possible to halt the vehicle within a reasonable distance in the event of the failure of the service braking system. It shall be possible to graduate this braking action. The driver shall be able to obtain this braking action from his driving seat while keeping at least one hand on the steering control. For the purpose of these requirements, it is assumed that not more than one failure of the service braking system can occur at one time., rikkepidur - pidur, mis tagab sõidupiduri rikke korral sõiduki peatamise, kusjuures juht peab olema võimeline sõidukit peatama, kasutades selleks ainult üht kätt. Rikkepiduriga pidurdamine peab olema reguleeritav.