| Track gauge | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Break-of-gauge - Dual gauge | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Gauge conversion (list) - Bogie exchange - Variable gauge | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Rail track - Tramway track | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Broad-gauge railways use a track gauge (distance between the rails) greater than the standard gauge of 1,435 mm (4 ft 8 1⁄2 in).
Contents |
In Britain the Great Western Railway, designed by Isambard Kingdom Brunel, pioneered broad gauge from 1838 with a gauge of 7 ft 0 1⁄4 in (2,140 mm), and retained this gauge until 1892. A number of harbours also used railways of this gauge for construction and maintenance. These included Portland Harbour and Holyhead Breakwater, which used a locomotive for working sidings. As it was not connected to the national network, this broad-gauge operation continued until the locomotive wore out in 1913.[1]
It became apparent that standardization on a single gauge throughout a rail transport system was advantageous. Rolling stock did not need to match the gauge exactly; a difference of a few millimeters could be coped with, so that interoperability on systems with gauges only slightly different was possible.
While the parliament of the United Kingdom of Great Britain and Ireland was initially prepared to authorise lines built to the broad gauge of 7 ft 0 1⁄4 in (2,140 mm), it was eventually rejected by the Gauge Commission in favour of all railways in the British Isles being built to standard gauge of 1,435 mm (4 ft 8 1⁄2 in), this being the gauge with the highest route-mileage. Ireland, using the same criteria, was allocated a different standard gauge, Irish gauge. Broad-gauge lines in Britain were gradually converted to dual gauge or standard gauge from 1864, and finally the last of Brunel's broad gauge was converted over a single weekend in 1892.
Many countries have broad-gauge railways. Ireland (see History of rail transport in Ireland) and some parts of Australia (see History of rail transport in Australia) and Brazil have a gauge of 5 ft 3 in (1,600 mm), but Luas, the Dublin light rail system, is built to standard gauge. Russia and the other former Soviet Republics use a 1,520 mm (4 ft 11 5⁄6 in) (originally 5 ft (1,524 mm)) gauge while Finland continues to use the 5 ft (1,524 mm) gauge inherited from Imperial Russia (the two standards are close enough to allow full interoperability between Finland and Russia).
In 1839 the Netherlands started its railway system with two broad-gauge railways. The chosen gauge was 1,945 mm (6 ft 4 23⁄40 in) after a visit of engineers to England and a large consignment of Brunel's lighter bridge rail removed from his "Bath Road" was imported for the construction. This was applied between 1839 and 1866 by the Hollandsche IJzeren Spoorweg-Maatschappij (HSM) for its Amsterdam-The Hague-Rotterdam line and between 1842 and 1855, firstly by the Dutch state, but soon by the Nederlandsche Rhijnspoorweg-Maatschappij, for its Amsterdam-Utrecht-Arnhem line. But the neighboring countries Prussia and Belgium already used standard gauge, so the two companies had to regauge their first lines. In 1855, NRS regauged its line and shortly afterwards connected to the Prussian railways. The HSM followed in 1866. There are replicas of one broad-gauge 2-2-2 locomotive (De Arend) and three carriages in the Dutch Railway Museum in Utrecht. These replicas were built for the 100th anniversary of the Dutch Railways in 1938–39.
The Baltic states have received funding from the European Union to build new lines with standard gauge. Portugal and the Spanish Renfe system use a gauge of 1,668 mm (5 ft 5 2⁄3 in) called "Ancho Ibérico" in Spanish or "Bitola Ibérica" in Portuguese (see Iberian gauge & Rail gauge); there are plans to convert to standard gauge.[2][3] In India, Pakistan and Bangladesh, a gauge of 5 ft 6 in (1,676 mm) is widespread. This is also used by the Bay Area Rapid Transit (BART) system of the San Francisco Bay Area. In Toronto, Canada the gauge for TTC subways and streetcars was chosen in 1861, years after the establishment of 'standard gauge' in Britain, but well before 'standard gauge' in the US and Canada. Toronto uses a unique gauge of 4 ft 10 7⁄8 in (1,495 mm), an "overgauge" originally stated to 'allow horse-drawn wagons to use the rails', but with the practical effect of precluding the use of standard-gauge equipment in the street. In 1861, the province was supplying subsidies only to broad 'provincial gauge' railways.
The value of interoperability was initially not obvious to the industry. The standardization movement was gradual; over time the value of a proprietary gauge diminished, being replaced by the idea of charging money for equipment used on other railroad lines.
The use of a non-standard gauge precludes interoperability of rolling stock on railway networks. On the GWR the 7 ft 0 1⁄4 in (2,140 mm) gauge was supposed to allow high speed, but the company had difficulty with locomotive design in the early years, losing much of the advantage, and rapid advances in permanent way and suspension technology allowed standard-gauge speeds to approach broad-gauge speeds within a decade or two. On the 5 ft 3 in (1,600 mm) and 5 ft 6 in (1,676 mm) gauges, the extra width allowed bigger inside cylinders and greater power, a problem solvable by using outside cylinders and higher steam pressure on standard gauge. In the event, the most powerful engines on standard gauge in North America and Scandinavia far exceeded the power of any broad-gauge locomotive.
For list see: List of broad gauges, by gauge and country
The first railway in British North America, the Champlain and St. Lawrence Railroad, was built in 1835-36 to 5 ft 6 in (1,676 mm) gauge, setting the standard for Britain's colonies for several decades. Today, this is commonly known as Indian gauge, but in 1851 the 5 ft 6 in (1,676 mm) broad gauge was officially adopted as the standard gauge for the Province of Canada, becoming known as the Provincial gauge, and government subsidies were unavailable for railways that chose other gauges. However, this caused problems in interchanging freight cars with northern United States railroads, most of which were built to standard gauge or a gauge similar to it. In the 1870s, mainly between 1872 and 1874, Canadian broad-gauge lines were changed to standard gauge to facilitate interchange and the exchange of rolling stock with American railroads. Today, all Canadian freight railways are standard-gauge, with only the Toronto Transit Commission operating the Toronto streetcar system and three of the Toronto subway lines on its own unique gauge of 4 ft 10 7⁄8 in (1,495 mm).
The British Raj in India adopted 5 ft 6 in (1,676 mm) gauge, although some standard-gauge railways were built in the initial period. The standard-gauge railways were soon converted to broad gauge. Reputedly, broad gauge was thought necessary to keep trains stable in the face of strong monsoon winds. Attempts to economise on the cost of construction led to the adoption of 1,000 mm (3 ft 3 3⁄8 in) gauge and then 2 ft 6 in (762 mm) and 2 ft (610 mm) narrow gauges for many secondary and feeder lines, particularly in mountainous terrain.
However, broad gauge remained the most prevalent gauge across the Indian Subcontinent, reaching right across from Iran into Pakistan to Burma and Kashmir to Sri Lanka. After independence, the Indian Railways adopted 5 ft 6 in (1,676 mm) as the standard Indian gauge, and began Project Unigauge to convert metre-gauge and narrow-gauge lines to this gauge. Some of the newer specialized rail projects in India, such as the Konkan Railway and the Delhi Metro, use Indian gauge. There was a move to use standard gauge for the Delhi Metro, but the decision was made to use Indian gauge to maintain compatibility with the rest of the rail network. The decision was later changed and several new lines, including the Airport Express Line, use standard gauge. The new Bangalore Metro, Mumbai Metro, and Hyderabad Metro systems, all in planning or under construction as of 2009[update], will be on standard gauge.
Because of the broad gauge, trains in India can carry standard shipping containers double-stacked on standard flatcars, which is more economical than single containers, but standard-gauge railways in North American and elsewhere must use special double-stack cars to lower the center of gravity and reduce the loading gauge.
As finally established, the Iberian gauge of 1,668 mm (5 ft 5 2⁄3 in) is a compromise between the similar, but slightly different, gauges first adopted as respective national standards in Spain and Portugal in the mid-19th century. The main railway networks of Spain were initially constructed to a 1,672 mm (5 ft 5 5⁄6 in) gauge of six Castilian feet. Those of Portugal were initially built in standard gauge, but by 1864 were all converted to a 1,664 mm (5 ft 5 1⁄2 in) gauge of five Portuguese feet – close enough to allow interoperability in practice.[4] The new high-speed network in Spain and Portugal uses standard gauge. The dual-gauge high-speed train RENFE Class 130 can change gauge at low speed without stopping.
As part of the railway gauge standardisation considered by the United Kingdom Parliamentary Gauge Commission, Ireland was allocated its own gauge, Irish gauge . Ireland then had three gauges, and the new standard would be a fourth.
The Irish gauge of 1,600 mm (5 ft 3 in) is used in Ireland and parts of Australia and Brazil. A severe disadvantage of Irish Gauge in Australia was it was too close to standard gauge to allow safe and effective dual gauge with a third rail, such as between Victoria and New South Wales. There was endless argument about the impractibility of third rail, especially turnouts, even of the Brennan Switch. [5]
Russian gauge or CIS gauge 1,520 mm (4 ft 11 5⁄6 in) is the second most widely used gauge in the world, and spans the whole of the former Soviet Union/CIS bloc including the Baltic states and Mongolia. Finland uses 1524 mm. The difference is clearly lower than the tolerance margin, so through running is feasible. Care must however be taken when servicing international trains because the wear profile of the wheels differs from that of trains that run on domestic tracks only.
The original standard of 1,524 mm (5 ft) was approved on September 12, 1842 with re-standardisation to 1520 mm taking place during the 1960s.
Originally, various gauges were used in the United States and Canada. Some railways, primarily in the northeast, used standard gauge; others used gauges ranging from 4 ft (1,219 mm) to 6 ft (1,829 mm). Problems began as soon as lines began to meet and, in much of the north-eastern United States, standard gauge was adopted. Most Southern states used 5 ft (1,524 mm) gauge. Following the American Civil War, trade between the South and North grew and the break of gauge became a major economic nuisance. Competitive pressures had forced all the Canadian railways to convert to standard gauge by 1880, and Illinois Central converted its south line to New Orleans to standard gauge in 1881, putting pressure on the southern railways.
In the early days of rail transport in the US, railroads tended to be built out of coastal cities into the hinterland, and systems did not connect. Each builder was free to choose its own gauge, although the availability of British-built locomotives encouraged some railroads to be built to standard gauge. As a general rule, southern railroads were built to one or another broad gauge, mostly 5 ft (1,524 mm), while northern railroads that were not standard-gauge tended to be narrow-gauge. Most of the original track in Ohio was built in 4 ft 10 in (1,473 mm) Ohio gauge, and special compromise cars were able to run on both this track and standard-gauge track.[6] When American railroads' track extended to the point that they began to interconnect, it became clear that a single nationwide gauge was desirable.
In 1886, the southern railroads agreed to coordinate changing gauge on all their tracks. After considerable debate and planning, most of the southern rail network was converted from 5 ft (1,524 mm) gauge to 4 ft 9 in (1,448 mm) gauge, nearly the standard of the Pennsylvania Railroad, over two remarkable days beginning on Monday, May 31, 1886. Over a period of 36 hours, tens of thousands of workers pulled the spikes from the west rail of all the broad gauge lines in the South, moved them 3 in (76 mm) east and spiked them back in place. The new gauge was close enough that standard-gauge equipment could run on it without difficulty. By June 1886, all major railroads in North America were using approximately the same gauge. The final conversion to true standard gauge took place gradually as track was maintained.[7]
In modern uses, certain isolated occurrences of non-standard gauges can still be found, such as the Pennsylvania trolley gauge. The Bay Area Rapid Transit (BART) system in the San Francisco Bay Area chose 5 ft 6 in (1,676 mm) gauge. The San Francisco cable cars use a narrow gauge of 3 ft 6 in (1,067 mm).
A number of North American streetcar lines intentionally varied from standard gauge. This may have been to make the streetcar companies less-tempting targets for takeovers by the steam railroads (or competing streetcar companies), which would be unable to run their trains over the streetcar tracks.[8] Pennsylvania trolley gauge was used on the former (defunct) Pittsburgh Railways and the defunct West Penn Railways (5 ft 2 1⁄2 in/1,588 mm) and is still used on the current Pittsburgh Light Rail, on some SEPTA lines such as the Philadelphia streetcar lines and the Philadelphia Market-Frankford subway line (5 ft 2 1⁄4 in/1,581 mm & 5 ft 2 1⁄2 in/1,588 mm) as well as in New Orleans (5 ft 2 1⁄2 in/1,588 mm).
Some applications require broader gauges, including:
These applications might use double track of the country's usual gauge to provide the necessary stability and axle load. These applications may also use much heavier than normal rails, the heaviest rails for actual trains being about 70 kg/m (141 lb/yd).
|
|
||||||||||||||||||||||||||