Gravity railroad

Gravity railroad

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A gravity railroad or Gravity railway (British English
British English
British English, or English , is the broad term used to distinguish the forms of the English language used in the United Kingdom from forms used elsewhere...

) is a railroad on a slope that allow cars carrying minerals or passengers to coast down the slope by the force of gravity alone. The cars are then hauled back up the slope using animal power or a stationary engine and a cable, chain or one or more wide, flat iron bands. The speed of the cars is controlled by braking mechanism on one or more cars on the train. The typical amusement park
Amusement park
thumb|Cinderella Castle in [[Magic Kingdom]], [[Disney World]]Amusement and theme parks are terms for a group of entertainment attractions and rides and other events in a location for the enjoyment of large numbers of people...

 roller coaster
Roller coaster
The roller coaster is a popular amusement ride developed for amusement parks and modern theme parks. LaMarcus Adna Thompson patented the first coasters on January 20, 1885...

 is designed from gravity railroad technology.

Types of gravity railroad


Some gravity railroads were designed to allow the weight of the descending loaded cars to lift the empty cars back up to the top, using a cable looped around a pulley at the top for a portion of the line. A later revision designed by John B. Jervis
John B. Jervis
John Bloomfield Jervis was an American civil engineer. He was America's leading consulting engineer of the antebellum era . Jervis was a pioneer in the development of canals and railroads for the expanding United States...

, used two separate tracks known as the loaded or heavy track which carried cars loaded with coal to the destination, and the light track, used to return empty cars to the mines. This method allowed cars to travel in a loop, without the need for passing sidings. A stationary steam engine and a looping cable, chain or iron bands were used to raise the empty cars up the lift planes. The cars then coasted down a slight grade to the next lift plane. When cars reversed direction at the ends of the line on a switch or turnout instead of a loop, the railroad was known as a switchback gravity railroad.

Switchback gravity railroad


The term "switchback gravity railroad" is sometimes applied to gravity railroads that used special self-acting (momentum
Momentum
In classical mechanics, linear momentum or translational momentum is the product of the mass and velocity of an object...

-driven) Y-shaped switches known as switchbacks
Zig Zag (railway)
A railway zig zag, also called a switchback, is a way of climbing hills in difficult country with a minimal need for tunnels and heavy earthworks. For a short distance , the direction of travel is reversed, before the original direction is resumed.A location on railways constructed e.g...

 to automatically reverse a car's direction at certain points as it descends; this essentially folds the incline across the slope in a characteristic "zig-zag" shape. (See diagram: car starts from point A, coasts through switch at B, and comes to a stop at C. Car then rolls through the switch again and proceeds to the switch at D, where the process is repeated.) A separate track was typically used to haul the empty cars back to the top.

The original implementation of this type of system is credited to the Mauch Chunk Switchback Railway, which hauled coal and passengers from 1827 until 1933. This was very popular with tourists, and led to the development of the roller coaster
Roller coaster
The roller coaster is a popular amusement ride developed for amusement parks and modern theme parks. LaMarcus Adna Thompson patented the first coasters on January 20, 1885...

.

Self-acting incline


In the UK, a self-acting incline is one in which the loaded wagons going down pull, via a cable and drum, the empty wagons going up. There might be two separate tracks, or a single track with a passing loop. This system was widely used on slate railways in Wales
Wales
Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...

.

A variation on this system is the cliff railway for passengers. Both passenger cars are equipped with water tanks and, at the start, both tanks are full. Water is then let out of the tank on the lower car until the difference in weight between the two cars causes them to move.

United Kingdom


The Ffestiniog Railway
Ffestiniog Railway
The Ffestiniog Railway is a narrow gauge heritage railway, located in Gwynedd, Wales. It is a major tourist attraction located mainly within the Snowdonia National Park....

 in Gwynedd
Gwynedd
Gwynedd is a county in north-west Wales, named after the old Kingdom of Gwynedd. Although the second biggest in terms of geographical area, it is also one of the most sparsely populated...

, northwest Wales
Wales
Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...

, was built in 1832 to carry slate
Slate
Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism. The result is a foliated rock in which the foliation may not correspond to the original sedimentary layering...

 from quarries high in the hills to the sea at Porthmadog
Porthmadog
Porthmadog , known locally as "Port", and historically rendered into English as Portmadoc, is a small coastal town and community in the Eifionydd area of Gwynedd, in Wales. Prior to the Local Government Act 1972 it was in the administrative county of Caernarfonshire. The town lies east of...

. The line was laid out for the wagons to descend by gravity, while horses were originally used to haul the empty wagons up the hill. On the downward journey the horses travelled in a Dandy waggon
Dandy waggon
The dandy waggon is a type of railroad car used to carry horses on gravity trains. They are particularly associated with the narrow gauge Festiniog Railway in Wales where they were used between 1836 and 1863.- The challenge :...

 at the rear of the train. Later on, steam haulage was adopted. This narrow gauge railway is still operational but all passenger trains are now locomotive-hauled.

Demonstration gravity trains are still occasionally run using original wagons - up to 50 at a time.

United States


In the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, The Delaware and Hudson Canal Company
Delaware and Hudson Canal
The Delaware and Hudson Canal was the first venture of the Delaware and Hudson Canal Company, which later developed the Delaware and Hudson Railway...

 operated an extensive gravity railroad system from 1828 until 1898. With 22 separate lift planes, the 55-mile (88 km) Pennsylvania Coal Company Gravity Railroad was the longest, and operated until 1885. A portion of the railroad was purchased in 1886 by the recently constructed Shohola Glen Summer Resort (1882) and used until 1907.

Due to the success and advancement of the gravity railroads, a gravity operation at Hawley and Pittston was created. This 47 mile route from Paupack Eddy (Hawley) and Port Griffith (Pittston) allowed Pennsylvania Coal Company's to directly ship anthracite from its mines to Hudson Canal and Delaware. This means of transportation ultimately led anthracite to the New York markets.

From 1896 through 1930, trains carried gravity cars up Mount Tamalpais
Mount Tamalpais
Mount Tamalpais is a peak in Marin County, California, United States, often considered symbolic of Marin County. Much of Mount Tamalpais is protected within public lands such as Mount Tamalpais State Park and the Mount Tamalpais Watershed.-Geography:...

 in Marin County, California
Marin County, California
Marin County is a county located in the North San Francisco Bay Area of the U.S. state of California, across the Golden Gate Bridge from San Francisco. As of 2010, the population was 252,409. The county seat is San Rafael and the largest employer is the county government. Marin County is well...

 and riders in the gravity cars then traveled down the 281 curves to the city of Mill Valley
Mill Valley, California
Mill Valley is a city in Marin County, California, United States located about north of San Francisco via the Golden Gate Bridge. The population was 13,903 at the 2010 census.Mill Valley is located on the western and northern shores of Richardson Bay...

. On May 3, 2009, a Gravity Car Barn was built on the top of the mountain to commemorate the old form of transportation, and a faithful replica of a gravity car was set on sixty feet of track.

Other inclined railroads


A funicular
Funicular
A funicular, also known as an inclined plane or cliff railway, is a cable railway in which a cable attached to a pair of tram-like vehicles on rails moves them up and down a steep slope; the ascending and descending vehicles counterbalance each other.-Operation:The basic principle of funicular...

 is not a true gravity railroad, as cars never coast freely and are always connected to a cable. A rack-and-pinion railway or rack railway
Rack railway
A rack-and-pinion railway is a railway with a toothed rack rail, usually between the running rails. The trains are fitted with one or more cog wheels or pinions that mesh with this rack rail...

is also not a true gravity railroad for similar reasons.

External links