Rapid Transit Technology - Crew Size and Automation

Crew Size and Automation

Early underground trains often carried an attendant on each car to operate the doors or gates, as well as a driver (often called the "motorman"). The introduction of powered doors around 1920 permitted crew sizes to be reduced, and trains in many cities are now operated by a single person. Where the operator would not be able to see the whole side of the train to tell whether the doors can be safely closed, mirrors or closed-circuit TV monitors are often provided for that purpose.

An alternative to human drivers became available in the 1960s, as automated systems were developed that could start a train, accelerate to the correct speed, and stop automatically at the next station, also taking into account the information that a human driver would obtain from lineside or cab signals. The first complete line to use this technology was London's Victoria Line, in 1968. In normal operation the one crew member sits in the driver's position at the front, but just closes the doors at each station; the train then starts automatically. This style of system has become widespread. A variant is seen on London's Docklands Light Railway, opened in 1987, where the "passenger service agent" (formerly "train captain") rides with the passengers rather than sitting at the front as a driver would. The same technology would have allowed trains to operate completely automatically with no crew, just as most elevators do; and as the cost of automation has decreased, this has become financially attractive. But a countervailing argument is that of possible emergency situations. A crew member on board the train may be able to prevent the emergency in the first place, drive a partially failed train to the next station, assist with an evacuation if needed, or call for the correct emergency services (police, fire, or ambulance) and help direct them.

In some cities the same reasons are considered to justify a crew of two rather than one; one person drives from the front of the train, while the other operates the doors from a position farther back, and is more conveniently able to assist passengers in the rear cars. The crew members may exchange roles on the reverse trip (as in Toronto) or not (as in New York).

Completely unmanned trains are more accepted on newer systems where there are no existing crews to be removed, and especially on light rail lines. Thus the first such system was the VAL (véhicule automatique léger or "automated light vehicle") of Lille, France, inaugurated in 1983.

Additional VAL lines have been built in other cities.

In Canada, the Vancouver SkyTrain carries no crew members, while Toronto's Scarborough RT, opening the same year (1985) with otherwise identical trains, uses human operators.

These systems commonly use platform-edge doors (PEDs), in order to improve safety and ensure passenger confidence, but this is not universal: for example, the Vancouver SkyTrain does not. (And conversely, some lines which retain drivers nevertheless use PEDs, notably London's Jubilee Line Extension. MTR of Hong Kong also uses platform screen doors, the first to install PSDs on an already operating system.) Rapid transit systems in the United States do not use PEDs, with the exception of the Las Vegas Monorail which was the first system to use them in the country because of the city's desert climate.

As to larger trains, the Paris Métro has human drivers on most lines, but runs crewless trains on its newest line, Line 14, which opened in 1998. Singapore's North East MRT Line (2003) is the world's first fully automated underground urban heavy rail line. The Disneyland Resort Line of Hong Kong MTR is also automated, with a staff riding with the passengers and Automatic platform gate.

See also People mover.