Control car

A control car, cab car (North America), control trailer, or driving trailer (UK, Ireland, Australia and India) is a non-powered rail vehicle from which a train can be operated. As dedicated vehicles or regular passenger cars, they have one or two driver compartments with all the controls and gauges required to remotely operate the locomotive, including exterior locomotive equipment such as horns, bells, ploughs, and lights. They also have communications and safety systems such as GSM-R or European Train Control System (ETCS). Control cars enable push-pull operation when located on the end of a train opposite its locomotive by allowing the train to reverse direction at a terminus without moving the locomotive or turning the train around.

Control cars can carry passengers, baggage, and mail, and may, when used together with diesel locomotives, contain an engine-generator set to provide head-end power (HEP). They can also be used with a power car or a railcar.

European railways have used control cars since the 1920s; they first appeared in the United States in the 1960s.

Control cars communicate with the locomotive via cables that are jumped between cars. North America and Ireland use a standard AAR 27-wire multiple unit cable, while other countries use cables with up to 61 wires. A more recent method is to control the train through a Time-Division Multiplexed (TDM) connection, which usually works with two protected wires.

In North America, cab cars are used primarily for commuter rail and, less frequently, for longer distance trains. There are both single and bilevel models; styling ranges from blunt ends to newer, more aerodynamic, streamlined cabs. They may be very similar to regular coaches, to the point of including a gangway between cars so that they could be used in the middle of a passenger train like a regular coach if necessary.

The Chicago and North Western Railway had 42 control cabs built by Pullman-Standard in 1960, which eliminated the need for its trains or locomotives to be turned around. It was an outgrowth of multiple-unit operation that was already common on diesel locomotives of the time. The Canadian transit agency Exo uses control cars on all its trains. Amtrak also has a number of ex-Budd Metroliner cab cars, which are used primarily for push pull services on the Keystone Service and Amtrak Hartford Line. The Long Island Rail Road uses cab cars on its C3 double deck coaches.

During the mid-1990s, as push-pull operations became more common in the United States, cab-cars came under criticism for providing less protection to engine crews during level crossing accidents. This has been addressed by providing additional reinforcing in cab cars. This criticism became stronger after the 2005 Glendale train crash, in which a Metrolink collided with a Jeep Grand Cherokee at a level crossing in California. The train was traveling with its cab car in the front, and the train jackknifed. Eleven people were killed in the accident, and about 180 were injured. Ten years later, in early 2015, another collision occurred in Oxnard, California, involving one of Metrolink's improved "Rotem" cab cars at the front of the train hitting a truck at a crossing. The truck driver left his vehicle before the impact, but the collision resulted in multiple car derailments and further cars jackknifing causing widespread injury.

From the 1970s until 1999, the Long Island Rail Road used a number of older locomotives converted to "power packs". The original prime movers were replaced with 600 horsepower (450 kW) engines/generators solely for supplying HEP with the engineer's control stand left intact. Locomotives converted included Alco FA-1s and FA-2s, EMD F7s, and one F9. One FA was further converted into a power car for the C1 bi-level cars in 1991. The railroad has since switched to classic cab cars with a DE30AC/DM30AC locomotive on some trains. Trains going into Penn Station require two DM30AC locomotives on each end in order to make use of their 3rd rail pickups.