Cable car (railway)

A cable car or cable railway is a mass transit system using streetcars (trams) that are pulled along a rail track by a continuously moving cable running at a constant speed. Individual cars stop and start by releasing and gripping this cable as required.

Operation

The cable is itself powered by a stationary motor or engine situated in a cable house or power house. The speed at which it moves is relatively constant, although somewhat influenced by the current load. Different systems have used different speeds, for example in San Francisco the current cable speed is 9.5 mph (15.3 km/h).

The cable car begins moving when a clamping device, called a grip, is connected to the moving cable. This is done by manually applying a clamp, called a grip, and resembing a very large pair of pliers to the moving cable. Strength and skill are required to operate the car, as the cable, if gripped suddenly, would instantly bring the car to operating speed, unacceptably jarring the passengers. The grip is applied evenly the start the cable car smoothly, rather like "slipping the clutch" on an automobile.

The car is stopped by detaching it from the cable, and then applying brakes. The vehicle itself has no motive power.

History

The street railway type of cable car was invented by Andrew Smith Hallidie, who was supposed to have been inspired by seeing a gruesome horsecar accident caused by a car running away on a San Francisco hill.

Halladie's system, the first to use grips, was tested in San Francisco at four o'clock in the morning on August 2, 1873 by . He envisioned cable cars as the solution for public transport along the steep streets on the hills of San Francisco. The system was indeed succesful, and was the model for all other cable car transit systems. Three lines of the San Francisco cable car system are still in operation and are a world famous tourist attraction, in addition to being a regular functional part of the city's transit system.

Halladie's system rapidly spread to other cities, although the major attraction for most was the ability to displace animal railways rather than the ability to climb hills. Chicago, a flat city, possessed the largest such system. Consequently, the development of the electrically-powered trolley precipitated the rapid decline of cable systems. Trolleys were cheaper to build, easier to operate, and could climb hills almost as well as cable cars except in the most extreme situations.

Advantages of cable railways

The cable cars primary advantages, of being to replace animal railways, and of being able to climb hills, were insufficient to keep lines very long after the trolley car was introduced, negating the first advantage. The second advantage existed in only a handful of cities.

Another advantage, not much considered today, is the relative energy efficiency of cable cars, first because of the economy of centrally located power stations, and because, in a hilly city, cars going downhill counterbalanced other cars going up.

Disdvantages of cable railways

Initially, the expensive infrastructure of a cable system was justified by the ability to replace animals as motive power, which many viewed as unnecessarily cruel, and the necessity to maintain large stables of draft animals (usually horses) that had to be fed (typically ~30 lbs. (~14 kg) of feed each day), housed, groomed, medicated and rested; a typical beast worked perhaps 4 or 5 hours per day, but when electric cars became practical barely more than a decade-and-a-half later, the infrastructure cost became a liability.

Cable lines require miles of continuous cable that must be maintained and may break under load, bringing down a line while the location of the break is found and repaired. The cables are carried in a vault between the rails through which the grip mechanism accesses the cable through a slot. This vault is subject to the elements, which may jam or corrode the mechanism, or damage the grip. Other complex elements are buried in the city streets. The cable has to be supported by pulleys, and taken around curves (both horizontal and vertical) by other pulleys or guides.

The gripman (as the operator is called) must know the route well and the operation of the cars. There are places where the cable must be dropped (switches, crossing other lines, some curves) and other places where it may not be dropped. There was a long stretch of line at Union Square in New York City known as "Deadman's Curve" where the configuration of the cable under the roadway prevented the cable from being let go. Any obstruction, whether human, animal, or vehicle, could bring both itself and the cable car to grief.

Compared to other cable railway systems

Funicular

A cable car is superficially very similar to a funicular but differs from such a system in several respects.

A funicular works on a balance system, in which cars, semi-permanently attached to the cable, are raised and lowered on (usually) adjacent tracks simultaneously. This arrangement is very energy-efficient as the weight of one car nearly balances the other, save the difference in passenger load. This means that there can be only two cars on a funicular line, unless some means of turning the cars at the end is provided.

While on a cable car system, each car operates independently, gripping or releasing the cable at will, on a funicular the cable itself is started and stopped, meaning that cars must be operated in tandem, requiring that passengers on each must be loaded and secured before either car can move. The cable line can operate many more cars than a funicular, and achieve higher capacity and operating flexibility.

The funicular, on the other hand, can operate on a much steeper grade, and this ability explains the much greater number of these systems existing. Some systems, such as the Wellington Cable Car in New Zealand, have intermediate stations, as does the system in Heidelberg, Germany.

Elevated railroads

A few elevated railroads used cable propulsion initially. The first cable car installation in operation was the West Side and Yonkers Patent Railway in New York, which ran from 1868 to 1870. The cable proving too troublesome, the line was closed, re-equipped and reopened with more conventional steam engines. This became the 9th Avenue Elevated line of the New York City transit system, since demolished.

The Brooklyn Bridge railway initially used cable haulage and for some years, with the cars switched at the Brooklyn end by steam engines. This was phased out and replaced by electric cars operated from third rail. The tracks were converted to streetcar use in 1940 and eliminated entirely in 1944.

Subways and Underground railways

A few early subway/underground railway systems also used cable propulsion, principally due to concerns over the use of steam traction in relatively poorly ventilated bored tunnels at a time when electric traction was still in its infancy.

City currently operating cable cars

San Francisco, California is well known for the San Francisco cable car system and is now the only city in the world which has more than one cable car route in permanent operation, and uses the Halladie system.

Cities previously operating cable cars

Australia

Melbourne, Australia
Sydney, Australia

Cable cars running on Broadway, New York City, 1897

External links

http://www.cablecarmuseum.com
http://www.cable-car-guy.com
The Cable Building (New York City) Broadway Cable car line.