Track gauge
By transport mode
Rapid transit Tram Miniature Scale model
By size (list)
Minimum   Fifteen inch 381 mm (15 in)   Narrow   600 mm 600 mm (1 ft11+5⁄8 in) Two foot 610 mm (2 ft) Two foot three inch 686 mm (2 ft 3 in)   750 mm 750 mm (2 ft5+1⁄2 in) Bosnian gauge 760 mm (2 ft5+15⁄16 in) Two foot six inch 762 mm (2 ft 6 in)   Swedish three foot 891 mm (2 ft11+3⁄32 in) 900 mm 900 mm (2 ft11+7⁄16 in) Three foot 914 mm (3 ft) Italian metre 950 mm (3 ft1+13⁄32 in)   Metre 1,000 mm (3 ft3+3⁄8 in)   Three foot six inch 1,067 mm (3 ft 6 in)   Four foot 1,219 mm (4 ft)   Four foot six inch 1,372 mm (4 ft 6 in)   1432 mm 1,432 mm (4 ft8+3⁄8 in)   Standard 1,435 mm (4 ft8+1⁄2 in)   Broad   Italian broad gauge 1,445 mm (4 ft8+7⁄8 in) Dresden gauge 1,450 mm (4 ft9+3⁄32 in)   Leipzig gauge 1,458 mm (4 ft9+13⁄32 in)   Toronto gauge 1,495 mm (4 ft10+7⁄8 in)   1520 mm 1,520 mm (4 ft11+27⁄32 in) Five foot 1,524 mm (5 ft)   Pennsylvania gauge 1,581 mm (5 ft2+1⁄4 in) Pennsylvania gauge 1,588 mm (5 ft2+1⁄2 in) Five foot three inch 1,600 mm (5 ft 3 in)   Baltimore gauge 1,638 mm (5 ft4+1⁄2 in)   Iberian gauge 1,668 mm (5 ft5+21⁄32 in) Five foot six inch 1,676 mm (5 ft 6 in)   Six foot 1,829 mm (6 ft)   Brunel 2,140 mm (7 ft1⁄4 in)   Breitspurbahn 3,000 mm (9 ft 101⁄8 in)
Change of gauge
Bogie exchange Break of gauge Dual gauge Conversion list Variable gauge
By location
North America South America Europe Australia

5 ft 6 in (1,676 mm) is abroad track gauge, used inIndia,Pakistan, westernBangladesh,Sri Lanka,Argentina,Chile, and onBART (San Francisco Bay Area).

In North America, it is calledIndian,Provincial,Portland, orTexas gauge. In Argentina and Chile, it is known as "trocha ancha" (Spanish for "broad gauge"). In theIndian subcontinent it is simply known as "broad gauge". It is the widest gauge in use of heavy-duty mainline railways in the world.

InIndia, the initial freight railway lines were built usingstandard gauge. In the 1850s, theGreat Indian Peninsula Railway adopted the gauge of1,676 mm (5 ft 6 in) for the first passenger railway in India betweenBori Bunder andThane.^[1][2] This was then adopted as the standard for the nationwide network.

Indian Railways today predominantly operates on1,676 mm (5 ft 6 in) broad gauge. Most of the metre gauge and narrow gauge railways have been converted to broad gauge. Small stretches of the network that remain on metre and narrow gauges are alsobeing converted to broad gauge.Rapid transit lines are mostly on standard gauge, although some initial lines use1,676 mm (5 ft 6 in) broad gauge. High speed rail routes, such as theMumbai–Ahmedabad high-speed rail corridor, use standard gauge.

Bangladesh Railways uses a mix of1,676 mm (5 ft 6 in) broad gauge andmetre gauge. The broad gauge network is primarily located to the west of theJamuna River, while the metre gauge network is primarily located to its east. TheJamuna Bridge is a mixed-use bridge that contains adual gauge connection across the river linking both networks.

In Nepal, all services currently operate on1,676 mm (5 ft 6 in) broad gauge only. Its predecessor,Nepal Government Railway used762 mm (2 ft 6 in) narrow gauge from 1927 to 1965.

In Pakistan, all services currently operate on1,676 mm (5 ft 6 in) broad gauge only, except for a 27.1 km (16.8 mi) line ofLahore metro.

In Sri Lanka, all services currently operate on1,676 mm (5 ft 6 in) broad gauge only.

The1,676 mm (5 ft 6 in) broad gauge was first used inScotland for two short, isolated lines: theDundee and Arbroath Railway (1836–1847) and theArbroath and Forfar Railway (1838–). Both lines were subsequentlyconverted tostandard gauge.

TheIberian-gauge railways, that service much of Spain and Portugal, have a track gauge of1,668 mm (5 ft 5+21⁄32 in), just8 mm (5⁄16 in) different from1,676 mm (5 ft 6 in). Used rolling stock from Iberia has been employed on broad-gauge lines in Argentina and Chile.

Canada became the first British colony, in the 1850s, to use1,676 mm (5 ft 6 in) broad gauge. It was known as the "Provincial gauge" in Canada.

The earliest railways in Canada, including the 1836Champlain and St. Lawrence and 1847Montreal and Lachine Railway however, were built to4 ft 8+1⁄2 in (1,435 mm)standard gauge.^[3]

TheGrand Trunk Railway which operated in several Canadian provinces (Quebec andOntario) and American states (Connecticut,Maine,Massachusetts,New Hampshire, andVermont) used it, but waschanged to standard gauge in 1873. The Grand Trunk Railway operated from headquarters inMontreal, Quebec, although corporate headquarters were inLondon,England. TheSt. Lawrence and Atlantic Railroad which operated inQuebec, 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 abreak-of-gauge with US railways, theWar 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.^[3]

TheBay Area Rapid Transit system is the only operating railroad in the United States to use1,676 mm (5 ft 6 in) broad gauge, with 120 miles (190 km) of double tracked routes. The original engineers chose the wide gauge for its "great stability and smoother riding qualities"^[4] and intended to make a state-of-the-art system for other municipalities to emulate. The use of1,676 mm (5 ft 6 in) broad gauge rails was one of many unconventional design elements included in its design which, in addition to its unusual gauge, also used flat-edge rail, rather than typical rail that angles slightly inward^[5] (although the shape of BART wheels and rail has been modified since then^[6]). This has complicated maintenance of the system, as it requires custom wheelsets, brake systems, and track maintenance vehicles.^[5]

TheNew Orleans, Opelousas and Great Western Railroad (NOO&GW) used1,676 mm (5 ft 6 in)broad gauge until 1872, and theTexas and New Orleans Railroad used1,676 mm (5 ft 6 in) broad gauge ("Texas gauge") until 1876. TheGrand Trunk Railway predecessorSt. Lawrence and Atlantic Railroad which operated inQuebec, Vermont, New Hampshire and Maine also used1,676 mm (5 ft 6 in) broad gauge ("Canadian gauge", "Provincial gauge" or"Portland gauge") but wasconverted in 1873. Several Maine railroads connected to the Grand Trunk Railway shared its "Portland Gauge". TheAndroscoggin and Kennebec Railroad and theBuckfield Branch Railroad were later consolidated as theMaine Central Railroad which converted tostandard gauge in 1871.John A. Poor's chief engineerAlvin C. Morton compiled the following advantages of "Portland Gauge" for Maine railways in 1847:^[7]

• 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 beforemechanical engineering encompassed a good understanding ofdynamics; and keeping such vibration close to the center of mass reduced theangular momentum causing rocking.
• Wider fireboxes andboilers 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 plowingsnow; 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.
• TheGrand Trunk Railway system feeding the seaport ofPortland, 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 toBoston 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.

The national railway network is predominantly on1,676 mm (5 ft 6 in) broad gauge.

Most links of1,676 mm (5 ft 6 in) broad gauge railways are in the center-south of the country. Only a few lines of the Ferrocarril del Sur (Southern Railroad Network) were1,000 mm (3 ft 3+3⁄8 in)metre gauge or1,435 mm (4 ft 8+1⁄2 in)standard gauge, the notable exceptions being one of the few active links: theRamal Talca-Constitución branch and theMetro de Santiago. On the contrary, just a few branches of the FCN (Ferrocarril del Norte) were broad gauge, most notably the Mapocho-Puerto mainline between Santiago and Valparaiso, theSantiago–Valparaíso railway line. This link was directly connected to the southern railroad network using the Matucana tunnel that connected Mapocho and the Central Station inSantiago. TheTransandine Railway that connected both Argentinean and Chilean broad gauge networks through the Uspallata pass in the Andes mountains was actually a1,000 mm (3 ft 3+3⁄8 in) narrow gauge link.

TheIberian gauge (1,668 mm or5 ft 5+21⁄32 in) is closely similar to the Indian gauge, with only8 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 and Portuguese Iberian-gauge rolling stock. 1,668 mm trains can run on 1,676 mm gauge without adaptation, but for better stability in high-speed running a wheelset replacement may be required (for example, Russian-Finnish trainAllegro has1,522 mm or4 ft 11+29⁄32 in gauge, intermediate between Russian1,520 mm or4 ft 11+27⁄32 in and Finnish1,524 mm or5 ft). Backward compatibility—1,676 mm trains on 1,668 mm gauge—is possible, but no examples and data exist. Due to the narrower gauge, a strong wear of wheelsets may occur without replacement.

• Broad-gauge railway
• Heritage railway
• List of track gauges

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