The Budd Rail Diesel Car (often shortened to RDC) is a Diesel Multiple Unit built by the Budd Company in response to a era of low ridership on passenger trains. It was specifically designed to be used on shorter routes, such as commuter runs or runs with low ridership. It is powered by twin Detroit Diesel Series 110 engines, and these were coupled to an automatic transmission, which drives the wheels.
The RDC was a moderate success, but in recent years their use began to dwindle; almost all RDCs running today are operated by tourist railroads. The only exception is VIA Rail Canada, which uses 6 RDCs of various types on its Budd Car service between Sudbury and White RIver, ON.
Some RDCs have since been de-motored and used as regular passenger cars, mainly in commuter service. Few of these cars survive.
These were the basic RDC cars; a diesel powered coach car with controls at both ends. They are also the most numerous of all types; most railroads still operating the RDC operates the RDC-1.
These were essentially RDC 1 cars, but with a baggage section at one end of the car. Very few examples exist.
Similar to the RDC 2, but with a larger baggage compartment. Very few examples exist.
These were essentially diesel powered baggage cars with controls. Only one example still exists; it is operated by VIA on its Sudbury-White River route.
These were "non-driving motor cars" with no controls and only one engine. It is coupled to other RDCs for increased capacity. Very few examples exist today.