5 ft 6 in gauge railway
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|Tram · Rapid transit
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|Break-of-gauge · Dual gauge ·
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5 ft 6 in/1,676 mm is the size of a broad track gauge commonly used in India, Pakistan, Bangladesh, Sri Lanka, Argentina, Chile, and on the BART (Bay Area Rapid Transit), in the San Francisco Bay Area. In South Asia it is simply known as "Broad gauge," while in North America, it is called Provincial, Portland, or Texas gauge or as Indian gauge elsewhere. It is the widest gauge in regular use anywhere in the world.
This gauge was first used in Scotland for two short, isolated lines, the Dundee and Arbroath Railway (1836-1847) and the Arbroath and Forfar Railway (1838- ). Both the lines were subsequently converted to standard gauge.
In the 1850s it was first used in Canada, and was then used in other British colonies. It was known as the "Provincial gauge" in Canada. The earliest railways in Canada, including the 1836 Champlain and St. Lawrence, 1839 Albion Colliery tramway and 1847 Montreal and Lachine Railway however, were built to standard gauge.
The Grand Trunk Railway which operated in several Canadian provinces (Quebec and Ontario) and American states (Connecticut, Maine, Massachusetts, New Hampshire, and Vermont) used it, but was changed to standard gauge in 1873. The Grand Trunk Railway which operated from headquarters in Montreal, Quebec, although corporate headquarters were in London, England. The St. Lawrence and Atlantic Railroad which operated in Quebec, Vermont, New Hampshire and Maine also used it but was converted in 1873.
There is a longstanding rumour that the Provincial gauge was selected specifically to create a break-of-gauge with US railways, the War of 1812 still being a fresh memory. However, there is little supporting evidence for this, and this story appears to be traced to a single claim from the late 1800s.
The Bay Area Rapid Transit system is the only operating railroad in the United State to use Indian gauge, with 104 miles (167 km) of mainlines. The original engineers for the system had background in aerospace (rather than railroads) and intended to make a state-of-the-art system for other municipalities to emulate. The use of Indian gauge rails was one of many unconventional design elements included in its design which, in addition to its unusual gauge, also uses flat-edge rail, rather than typical rail that angles slightly inward. This has complicated maintenance of the system, as it requires custom wheelsets, brake systems, and track maintenance vehicles.
The New Orleans, Opelousas and Great Western Railroad (NOO&GW) used Indian gauge until 1872, and the Texas and New Orleans Railroad used Indian gauge ("Texas gauge") until 1876. The Grand Trunk Railway predecessor St. Lawrence and Atlantic Railroad which operated in Quebec, Vermont, New Hampshire and Maine also used Indian gauge ("Canadian gauge" or "Portland gauge") but was converted in 1873. Several Maine railroads connected to the Grand Trunk Railway shared its "Portland Gauge". The Androscoggin and Kennebec Railroad and the Buckfield Branch Railroad were later consolidated as the Maine Central Railroad which converted to standard gauge in 1871. The only electric streetcar system in the U.S. to use this gauge was that of Fairfield, Maine.
- Frost heaves (swelling of wet soil upon freezing) produce an uneven running surface causing an irregular rocking motion as trains moved past. A wider wheelbase offered a steadier ride with less wear on the machinery and roadbed.
- Wider cars offered more room for passengers and cargo. Train length would be reduced for cars carrying the same amount of cargo. Shorter trains would lessen the effects of side winds, and permit more efficient application of power.
- Wide gauge locomotives offered more room to place reciprocating machinery inside, rather than outside the driving wheels. Reciprocating machinery was a source of vibration before mechanical engineering encompassed a good understanding of dynamics; and keeping such vibration close to the center of mass reduced the angular momentum causing rocking.
- Wider fireboxes and boilers allowed more powerful locomotives. The alternative of longer boilers held the disadvantage of poor firebox draft through the increased frictional resistance of longer boiler tubes.
- More powerful locomotives carrying fewer, larger cars would have reduced manpower requirement for engine crews and shop personnel.
- For locomotives of equal power, fuel consumption increased as gauge decreased, especially in colder outside temperatures.
- More powerful wide gauge locomotives would be more capable for plowing snow; and thereby provide more reliable winter service.
- Several gauges were in widespread use, and none had yet come into clear dominance.
- Freight transfer was preferable to exchange of cars between railways because unowned cars were abused on foreign railways.
- The Grand Trunk Railway system feeding the seaport of Portland, Maine offered little need for gauge transfer prior to loading on export shipping.
- Potential advantages of freight transfer to the standard gauge railroad from Portland to Boston seemed insignificant as long as competitive rates were available for transport on steamships between the two ports.
- The majority of Canadian freight anticipated to be carried over rail lines to Portland was heavy and bulky in comparison to its value, and must be transported cheaply in large quantities to maintain profitability for producers and transporters.
In India, the Governor-General James Andrew Broun-Ramsay, 10th Earl of Dalhousie determined that a wider gauge than 1,435 mm (4 ft 8 1⁄2 in) standard gauge was more suitable for larger fireboxes and for greater stability in high winds and long steep gradients.
The first agreement of the Government of India with the East Indian Railway Company and Great Indian Peninsula Company in 1849 stipulated that railways in India would be built on a four feet, eight and half inch gauge(later called standard gauge). However, soon there were disagreements with Lord Dalhousie favoring a 6 ft (1,829 mm) gauge while Mr. Simms, the consulting engineer, favored five foot, six inch gauge(a broad gauge). The debate was finally settled in favor of the five foot six inch gauge. The first train that ran from Bombay to Thane ran on 1,676 mm (5 ft 6 in) broad gauge.
Rail transport in India today is completely on 1,676 mm (5 ft 6 in) broad gauge barring urban rail and heritage railways.
In Pakistan all services currently operate on 1,676 mm (5 ft 6 in) broad gauge only.
Bangladesh Railways uses a mix of 1,676 mm (5 ft 6 in) broad gauge and metre gauge. The broad gauge network is primarily located to the west of the Jamuna River, while the metre gauge network is primarily located to its east. The Jamuna Bridge is a mixed use bridge that contains a dual gauge connection across the river linking both networks.
In Sri Lanka all services currently operate on 1,676 mm (5 ft 6 in) broad gauge only.
Iberian gauge (1,668 mm or 5 ft 5 21⁄32 in) is closely similar, with only 8 mm (5⁄16 in) difference, and allows compatibility with the rolling stock. For example, in recent years Chile and Argentina have bought second hand Spanish/Portuguese Iberian-gauge rolling stock.
|Paraguay||The Paraguayan railway from Asunción to Encarnación was originally laid in this gauge, in the hope that the connecting line from Posadas to Buenos Aires would be built to the same gauge; alas, this line was laid to standard gauge, and when the FCPCAL reached Encarnación in 1912 the whole line had to be re-gauged to standard gauge to allow through-working.|
|United Kingdom||Two early (1830s) linked railways around Arbroath (see Scotch gauge). (converted to standard gauge)|
- Omer Lavallee, "The Rise and Fall of the Provincial Gauge", Canadian Rail, February 1963, pp. 22-37
- Gafni, Matthias (March 25, 2016). "Has BART's cutting-edge 1972 technology design come back to haunt it?". San Jose Mercury News. Retrieved March 28, 2016.
- Holt, Jeff (1985). The Grand Trunk in New England. Railfare. p. 78. ISBN 0-919130-43-7.
- "Canada's Digital Collections archived at Library and Archives Canada". Government of Canada. Retrieved 2007-11-29.