Transit vehicles should be maintained per manufacturer guidelines and warrantees in order to help avoid any mechanical failures that limit or impede any function of the vehicle while it is operating in service. This calls for the need to follow preventative maintenance schedules and regular vehicle inspections to ensure that any issues are discovered prior to the vehicle being in service. This measure is assessed by how often mechanical failures happen while the vehicle is in service and results in the need for a road call. The target for this measure is set at less than one road call per every 10,000 vehicle miles traveled, and should be considered at the system level only.