Infrastructure: The importance of railway gauge and setting the standard

By The Helpful Engineer / On / In Infrastructure

This week, during testing, the first German ICE high speed train travelled through the channel tunnel thus hopefully paving the way for some price competition for travellers using the channel tunnel. It will be some time before paying passengers can make the journey on the German ‘ICE’ trains as there is disagreement over safety. This disagreement is related to the length of the German trains and the numbers of motors they contain.

Train lengths

The current (French TGV) trains using the tunnel are designed to be long enough so that one part of the train if stopped in the tunnel would always be adjacent to an emergency exit link to the escape tunnel. Passengers could then walk along the inside of the train the exit nearest the escape tunnel entrance and thus be protected from smoke, in the case of a fire, for longer. But the German ICE trains are actually two trains linked together. This would mean that, in an emergency evacuation inside the tunnel, some passengers would have to spend a longer time walking outside the train before finding the exit to the escape tunnel.

Train motors

The French also believe that the German trains are more susceptible to catching fire in the tunnel as they have a motor under each carriage (this is called distributed traction) rather than the French TGV train system which has separated locomotives pulling the train. The French consider that fewer motors means less risk of a fire, or at least fewer things that can go wrong once the train enters the tunnel. But it also suits the French to try to block new train types using the tunnel as at present only their TGV meets the safety rules. It seems likely that the tunnel safety rules will be relaxed to allow the ICE train use it, which will be good news for consumers.

Arguments like this are nothing new to engineering. The story of the selection of railway gauges is one of those fascinating disagreements which has had long reaching consequences.

Railway gauges

The gauge of a railway is the distance between the rails. At first when designing railways, engineers could select different gauges depending on the requirements of the particular line. The first railway lines were usually short sections linking, for example, a one coal pit to a canal or port and it made little difference if adjacent railways had different gauges. However as railways became more popular it became impossible to link them together if they had different gauges. This caused huge problems when trying to transfer between lines with different gauges, with cargo having to be taken off one train and put on another. Britain finally decided to settle on one gauge (4 ft 8.5ins) and changed all the other existing gauges to this. The selected gauge, which was chosen first by George Stephenson for his railway and only later adopted for the whole of Britain, became known as standard gauge across the world, because of Britain’s unique position and importance in railway technology at the time.

Christian Wolmar describes this issue very well in his latest and entertaining book ‘Blood, Iron and Gold – How railways have transformed the world’. His description of railway gauges is particularly interesting:

“Gauge plays an all too important role in this story because disputes over that crucial distance between the rails encompass a diverse range of other issues such as cost and speed, and making the wrong choice often resulted not only in massive sums of money being wasted but also jeopardizing the profitability of whole railway networks. Gauge was a compromise between cost and practicality and Stephenson got it about right, which explains the popularity of his choice. Wider railways obviously cost far more to build and take up much more land, but could offer greater standards of comfort. Narrower railways were cheaper, slower and not able to accommodate as many people.”

Probably the greatest engineer of all time, Isambard Kingdom Brunel, designed his railways to be the fastest and most comfortable possible for the time but the gauge this required at 7 feet wide was more than two feet larger than standard gauge. This larger gauge had huge implications for tunnels and bridges which were significantly more expensive to build. In the end it took until 1900 before the 200 miles of track built to this gauge had been converted to standard gauge. To this day his tunnels seem strangely spacious compared to the other built to smaller gauges.

Irish Gauge

Ireland now uses a different gauge to standard even though its first railway was built to standard gauge. The board of trade in Ireland decided to set a gauge for the country and asked for the Stephenson’s advice (after standard gauge had been set in Britain), but rather than press for the gauge width that they had created in England, bizarrely they suggested something between 5ft and 5ft 6ins and so the Irish Board of Trade took their advice and split the difference. The Irish gauge ever since has been 5ft 3ins. This extra distance meant that the Irish train carriages were more spacious for the travelling public than those in Britain. However the inconvenience to travellers crossing the Irish Sea was considerable as ferry boat trains could not be introduced as elsewhere and instead passengers and cargo had to disembark on each side of the Irish Sea to access the boat, rather than the train being able drive onto the ferry with the passengers and cargo aboard.

Failure in Australia

The Irish decision to have a different gauge was to have disastrous consequences on the other side of the world. As Wolmar also explains in his book:

“In 1846 the British Colonial Secretary had recommended that the Australian railways be built to standard gauge, but F.W. Shields, the chief engineer of the Sydney Railway Company was an Irishman, familiar with the 5ft 3ins gauge which he persuaded the New South Wales government to adopt. The Victorian and South Australian governments decided to fall into line and altered their gauges to conform with New South Wales and several railway companies which had sprung up in Victoria during 1852 ordered rolling stock on that basis. Then, suddenly, Shields resigned over a salary cut and his replacement, James Wallace, was an Englishman with an attachment to the standard gauge. Despite protests from the other two states, the change went through and New South Wales built its railways to the standard gauge while Victoria and South Australia held firm, arguing that it would be too costly to alter their rolling stock. As the chroniclers of the history of the Australian railways put it ‘the glorious bungle began’. In fact, it was not glorious but it was to prove expensive and a permanent handicap to the railways on which millions of dollars are still being spend to remedy the situation in the twenty first century. When the railways finally met at Albury in June 1833, it showed the broken gauge in all its limitations and folly. Moreover, two other mainland states, Queensland and Western Australia, along with Tasmania, adopted a narrow 3ft 6ins gauge, which meant that a transcontinental journey could require two changes of train. South Australia has the dubious distinction of having three different gauges – narrow, broad and standard, causing innumerable problems of break of gauge.”

Russia makes an intelligent choice

Standard gauge was selected for most of mainland Europe. But Russia and Spain who came late to railway building selected a different gauge, and surprisingly they both did this on purpose. Their thinking was that it would be a military advantage to have a railway system with different gauges to that of their potential enemies, with whom they shared long borders. Both ignored the economic disadvantages of such a decision. It was to be a fateful choice for Russia as it is possibly the only reason why Moscow was saved from being seized by Hitler in 1941. During the Second World War the vast majority of long distance transport by the German army was by train. The supplies and men would collect by train at the railhead closest to the front prior to launching an attack. When ground was occupied the railway was extended or repaired and the process repeated. When Hitler invaded Russia in 1940 his army had to change the gauge of all the tracks located in occupied Russian territory to suit the German trains. But this slow process meant that the advancing troops and tanks soon outran the new railway being constructed behind them. This caused havoc and slowed the advance of the forward tank (panzer) units who required regular supplies of oil, ammunition and other supplies. When the cold winter weather finally stopped the German advance, their furthest forward troops had already reached the outer suburbs of Moscow. If the army had been even a week ahead of their actual schedule, Moscow would surely have been taken or at least surrounded and cut off. It seems that the delay caused by changing the Russian railway gauge had enough of an impact to prevent the Russian capital being seized. It was a farsighted and fateful decision that the Russian engineers had made 100 years earlier.

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