Gauges and Wheels

by Michael Frewston

  The above definition holds true no matter what the gauge, whether narrow or broad gauge, and regardless of what type of vehicle is running on it.

  COMMON GAUGES IN THE WORLD:

  When you start to research all the different gauges that exist in the world, you come up with an astonishing number – a total of around 160! Many of these however differ from each other by a few millimetres only, and in fact, where these very minor differences occur on adjacent railways, they are of such small significance that trains are often run on both gauges without difficulty.

  These 160 different gauges can be distilled down to just a dozen or so of the most important ones – i.e. those that are predominant in a country or territory, those involving substantial distances, or those reflecting some form of strategic or economic importance.

  The most common gauge is of course Standard gauge, and this will be found to cover approximately 60% of the world’s track distance. The remaining 40% covers all the remaining gauges, of which Russian gauge is by far the largest component in terms of track distance, representing some 18% of the world’s route distance.

  The following summarises the distribution of gauges throughout the world, with a total route distance (excluding gauges smaller than metre-gauge, for which I have no total figures) of 1 256 000 km:

  Rather than go into any more detail regarding all the countries where each of these gauges can be found, Parts 2 to 7 in this book will list each country, or related group of countries, and the gauges to be found there, including detailed maps where possible, as well as pictures of the trains and trams using those gauges.

  There are also other gauges not shown in my list (some now defunct), such as Brunel’s broad gauge of 2140 mm (7 ft 0.25 in). Again, these will be covered in the appropriate chapters or countries.

  Notwithstanding the geographical names found in the list above (such as Indian gauge or Cape gauge), some of these gauges will be found in many parts of the world, often as a result of the influences and political exigencies that existed at the time railways were first established in those countries.

  HOW STANDARD GAUGE CAME ABOUT:

  The number of ‘urban myths’ describing how Standard gauge of 1435 mm came about is quite remarkable. In reality, the true story may never be known, lost as it is in the mists of time, going back as much as 3000 years ago and maybe even earlier. But there are enough common elements in all these stories to make an educated assumption that is likely to be as accurate as it will be possible to get.

  The earliest known ‘tracks’ are to be found in Malta, believed to be 4000 years old, or even older. There can be found deep ruts formed into the base bedrock in a number of areas where many ancient ruins were built. These ruts were about 1.2 m apart, and this dimension was maintained quite consistently. It is not known whether these ruts were a ‘railway’ as such, or had some other, unknown, purpose, as no vehicles of any kind have been found that could be associated with them.

  It is well known that Neolithic wheeled carts found in Europe had wheel ‘tracks’ (the distance between the wheels) that varied from 1.3 m to 1.75 m. Many such vehicles travelled continuously over the same crude unpaved roads or tracks and thus produced ruts, which got ever deeper as more vehicles passed. At this point it was found that a uniform wheel track enabled passage to be more easily accomplished, as all wheels on all vehicles could travel within, and not on top of, the ruts. The bottoms of the ruts provided a much firmer, and hence easier, foundation over which wheels could travel, than the surface of the road or track, which would likely be soft and muddy – no roads were paved as such in these early times.

  Wheel tracks appeared to have stabilized between 1.4 m and 1.5 m in the following years, including those of the Roman Empire. The advantages of a common wheel track became much more evident when the ancient Assyrians, Babylonians, Persians, but particularly the Greeks, constructed roads with artificial wheel-ruts cut in rock track-ways. Such ruts were naturally spaced at the wheel track of a typical cart or carriage – i.e. around 1.5 m.

  In ancient Greece, such ancient stone ‘railways’ (i.e. a railway being defined as any form of track-way where there was positive guidance to the wheels running over it) connected a number of major cities with sacred sites. The gauge of these stone grooves was set at about 1.4 m, although in practice they varied between 1.38 m and 1.44 m.

  Around 600 BC, the Diolkos in ancient Corinth was constructed, which some consider to be the world’s first, albeit rather rudimentary, railway. The Diolkos consisted of a granite road with artificially grooved tracks, along which large wooden vehicles carrying ships and their cargo were pulled by slaves or draft animals. The space between the grooved tracks in the granite was slightly wider than other contemporary track-ways, at a consistent 1.6 m, occasionally a bit less, but within reasonable tolerances considering how crude a stone track-way is to start with. Nonetheless, the grooves provided positive wheel guidance, just like a modern railway track does today.

  The Romans also used a more or less consistent wheel gauge throughout Europe, likely adopted from the Greeks, and even brought it to England with the Roman conquest of Britain in AD 43. After the Roman departure from Britain, this more-or-less ‘Standard gauge’ continued in use for the next 1800 years. It was therefore inevitable then that the wheel tracks of animal-drawn vehicles in early 18th century Britain, and the consequential ruts they produced, followed that from much earlier times – i.e. around 1.4 m to 1.5 m.

  As a road system was developed in Britain, starting in the 17th century, but progressing substantially in the 18th century, these ruts had timber bases inserted into them, which provided a much firmer and smoother foundation on which the wagon or cart wheels could travel, and which also helped to prevent the wear that would otherwise have occurred, making the ruts ever deeper. It was obvious that a constant width became necessary in order to enable as many vehicles as possible to travel in these ruts. By the same token, the wheel tracks of such vehicles also had to be made to fit in them. By default, and consciously or unconsciously, that width was somewhere between 1.4 m and 1.5 m.

  A similar situation occurred in the USA in the 19th century. In fact, in that country, a number of the states enacted laws requiring road vehicles to conform to a standard ‘gauge’. This was done to minimise the damage caused to the road surface, by ensuring that vehicles always followed the same ruts.

  In Germany, in the late 17th century, the beginnings of a railway as we know it were developed, when actual wooden flanged wheels running on flanged ‘rails’ were invented. But they were not successful, wood being a poor material for this kind of application. Nonetheless, the rails of this wooden railway were consistently and uniformly about 1.5 m apart, and established the first principles of a railway as it exists today.

  Thus it can be seen that any form of conscious effort to create a wheel track width, or ‘gauge’, usually settled on a distance of between 1.4 m and 1.5 m, starting from the earliest times (at least 3000 years ago), when wheeled vehicles came into general use, and continuing with rarely any major variation throughout the development of civilisation, until the beginnings of railways as we know them, about 200 years ago.

  So was that how Standard gauge came about? Not quite, at least not initially. For a start, an approximate track width of between 1.4 m and 1.5 m is hardly a single ‘gauge’ as such, just a range of wheel track widths that had proved practical in the past. But this general track width did provide direction on the later development of a single gauge. Secondly, the very first attempts at building railways actually used a variety of gauges, albeit with not a lot of difference between them.

  The first instances of metal flanged wheels running on rails are evidenced by the efforts of one Lord Penrhyn, who, in the late 18th century, invented a double flanged wheel running on, at first, a cast iron oval shaped rail, which was later changed to a flat topped rail. Double flanged wheels however had the disadvantage of great difficulty in creating workable switches and crossings, and
it is Richard Trevithick who is credited as having made and operated the world’s very first railway, as defined by single inside flanged iron wheels running on two iron rails a fixed distance apart.

  On 21 February 1804 the world's first locomotive-hauled railway journey took place, as Trevithick's unnamed steam locomotive hauled a coal train along the tramway of the Penydarren Ironworks, in Merthyr Tydfil in Wales. The gauge of this tramway was 1320 mm (4 ft 4 in).

  John Blenkinsop, building on Trevithick’s experiences, built a railway at Middleton Colliery, to 1524 mm (5 ft 0 in) gauge. He added a cogged rack with cog wheels on his locomotives, as he feared that there would be insufficient adhesion using friction alone, but otherwise this was a true railway in every sense of the word.

  (I have not mentioned the Swansea and Mumbles Railway, technically the world’s first passenger-carrying service using guided wheel vehicles, which opened in 1807, as it was built initially using flangeless wheels on a plateway, rather than using flanged wheels on rails. It was converted to a 1435 mm Standard gauge railway in 1855.)

  Serious railway building then proceeded, slowly at first, but then increasing rapidly in a frenzy of activity. There was however little communication or co-operation, and therefore agreement, between the various builders and engineers involved. The following table shows most (though by no means all) of the early pioneering railways in Britain in the early 1800s and the gauges that were used.

  As can be seen, there was reasonably close, but far from exact, uniformity in gauges selected. While there may have been some through running on adjacent lines that used track gauges that varied by no more than 13 mm or so, there was not sufficient uniformity to permit unrestricted through running as the various lines met up, which of course they inevitably did. George Stephenson, realising the huge difficulties if unrestricted through running was not possible, started to push for a common gauge – and that this gauge should be 1435 mm.

  The first defining railway event in the world was the Rainhill Trials, in 1829, during which George Stephenson’s Rocket proved superior to all other locomotives, and was declared the winner. These trials were conducted on a stretch of line that was to become part of one of the world’s first true public railways, the Liverpool and Manchester Railway, and it is obviously significant that this stretch of track was built to 1435 mm gauge, as were of course all the vehicles that took part in the trials.

  Quite why 1435 mm, and not, say, 1524 mm (an even 5 ft) was selected is not clear, as indeed some early railways in the table above did use 1524 mm, especially those in the London area. A little speculation can perhaps provide a plausible explanation.

  Based on bits of history here and there, it seems likely that Stephenson’s first railway efforts made extensive use of northern mine colliery vehicles, which date from the 17th century. These colliery vehicles used to run on some sort of guided trackway or plateway in the mines, where their flangeless wheels were guided by L-shaped rails. We have already seen that a width or track of around 1.5 m was by now quite well established.

  Some plateways used L-shaped rails with the vertical legs on the inside, while others had the vertical legs on the outside. The latter were more common. These vertical outside legs of the L-shaped rails were likely an even 5 ft (1524 mm) apart. This meant that the colliery vehicles had a wheel track (measured outside-to-outside) also of that even 5 ft. Let us assume these wheels each had a tread width of 51 mm (2 in). When a flange was added to the inside of each wheel, the distance between the flanges (measured at the ‘throat’, or junction between flange and tread) was thus reduced by 102 mm (2 x 51 mm), to 1422 mm, or 4 ft 8 in. After Stephenson found that a little more lateral play was required to reduce binding on sharp curves, he added that extra 13 mm (0.5 in) to produce 1435 mm.

  There has been proposed an alternative explanation of how 1435 mm came to be Standard gauge. This measurement equates almost exactly to 2.75 Egyptian cubits, or exactly 1/4 of the length of the Queen's Chamber in the Great Pyramid. Egyptian measuring units, especially those embodied in the Great Pyramid, were quite well known to British engineers, as early as the end of the 18th century, and it is said that such engineers were often disposed to using such measurement units in those early days.

  Could Stephenson have made a relatively elegant 2.75 cubits his reason for choosing what, in Imperial units, is an odd gauge? It’s possible. Like I said earlier though, the true story may never be known, and whether Stephenson used Egyptian cubits or colliery coal wagons as the basis for choosing 1435 mm, I will leave it to the reader to decide.

  Some of the early railways were built to a slightly wider gauge – 1448 mm (4 ft 9 in), likely (although this is not known for sure) in order to provide even more lateral movement. Although it was determined that 1435 mm gauge vehicles could run satisfactorily over these tracks, the extra 13 mm simply adding a little extra tolerance, such extra tolerance was found unnecessary. Eventually as their tracks were replaced during routine maintenance, these railways were converted to 1435 mm.

  This gauge of 1435 mm initially became known as Stephenson gauge. George Stephenson was a very influential person, and carried considerable authority in engineering circles. This authority even enabled him to be made the first president of the Institution of Mechanical Engineers on its formation in 1847. It seems likely that Stephenson’s influence and persuasiveness was a major factor in ensuring that 1435 mm became the Standard gauge in England.

  [There was probably much more to it than the simple explanations I have described above – history records many early attempts by various railway pioneers in experimenting with different forms and profiles of rails and wheels, each of which would result in a different actual ‘gauge’, even when using the same ‘nominal’ width between wheels – but that is getting into a lot of extra detail that, while interesting in itself, departs from the story on how Standard gauge came about. I feel that Stephenson’s work was the most important influence on settling on 1435 mm as Standard gauge. That is why I have concentrated on his work, and feel that it is the defining factor.]

  However, there were still many early railway builders in the land who did not see eye-to-eye with George Stephenson on his choice of gauge, at least to the point that it should become the recognised standard. One such pioneer was Isambard Kingdom Brunel, credited as being one of the greatest engineers ever, and who decided that a track gauge of 2134 mm (7 ft 0 in) was much superior. And, from a purely technical perspective, Brunel was possibly quite right, at least in his day, as a number of contests between his broad gauge trains and competing Standard gauge trains demonstrated in no uncertain manner – his broad gauge locomotives were staying on the track well after Standard gauge locomotives had fallen off.

  The broader gauge, reasoned Brunel, would provide much better stability, especially on curves, and would allow for higher speeds. In addition, the increase in vehicle size that the wider gauge made possible allowed for more powerful locomotives, as well as increased space, and hence load-carrying capacity, within coaches and wagons for both passengers and freight alike.

  In 1838, some eight years after the 1435 mm gauge Liverpool and Manchester Railway was opened, Brunel started building his Great Western Railway (GWR) in the west and south-west of England at his broad gauge, adding an extra 6 mm (0.25 in) for that needed additional lateral play on curves, to produce a gauge of 2140 mm (7 ft 0.25 in). Brunel laid all his rails on longitudinal wood bearers connected by non-load-bearing cross-ties (this, at the broader gauge, being a less expensive method of construction than the transverse sleepers type of construction that was being used elsewhere, and is universal today).

  Where his trains used common trackage with Stephenson gauge trains, dual gauge track was laid, using the same longitudinal bearer method. Much of Brunel’s trackage had to have an additional Standard gauge rail added to permit interfacing with other companies’ railways, especially in parts of South Wales. Dual-gauge rails even reached the very heart of London, including Paddington and what
is now Victoria Station, where, in April 1863, both Great Western broad gauge and London, Chatham & Dover Railway Stephenson gauge trains ran between Southall, Kensington and Victoria Station, making use of the West London Railway. (The arrangement however was not a success, and the broad gauge trains had all stopped working into Victoria Station in less than four years.)

  All other efforts at creating different gauges were thwarted by the Gauge Act of 1846 (see below), and, apart from Brunel’s broad gauge, all main-line railways in Britain (except for some minor railways) were either newly built, or later converted, to Standard gauge by the end of the 1860s.

  GAUGE WARS:

  The Table in the previous chapter shows that over a dozen British railways were already operating by the early 1840s, with no uniformity of gauges in sight. While most of those railways were fairly close in gauge (but often not enough to permit unrestricted through running once they had the potential of joining up), Brunel continued to present a rather large fly in the ointment by insisting on going his own way with his 2140 mm broad gauge.

  By the mid-1840s, there were over 200 applications for new railway lines, and still there was no agreement as to which gauge they should be built to. Clearly something needed to be done.

  In 1845 a Royal Commission was set up and which looked into the subject of Britain’s railway gauges. After a long investigation, involving many sometimes highly technical submissions by eminent engineers and prominent financiers alike, it was decided, against even the Commission’s own findings, to recommend the use of Stephenson’s 1435 mm gauge as being the new Standard gauge in England, Wales and Scotland.

  The Gauge Act passed by Parliament in 1846 made Standard gauge compulsory for all new railways – a decision that not only affected all future railway construction in Great Britain, but in very many other parts of the world as well. (The Commission at the same time specified a different gauge for Ireland, and that will be covered later.)