Gauges and Wheels

by Michael Frewston

  This additional height allows the use of stepped inside faces on the tram wheels – the lower faces 1380 mm apart for running on grooved tram rails and the upper faces 1360 mm apart for running on train rails. On sharp curves and through switches and crossings, the upper section of the inside face is in contact with train check rails, while the lower part is in contact with tram track inside rail flanges.

  Problem solved – at least partially. There is still the flange depth consideration, where the train wheel needs to run on its flange for support (such as at a right-angled crossing), using a length of steel blocking on the inside of the rail and at a height corresponding to the bottom of the train wheel flange. Such support prevents the train wheel from ‘bumping’ across the gap where the two rails cross. At such locations, the tram wheel’s flange is not deep enough to be supported, thus causing the tread of the tram wheel to ‘bump’ across this gap.

  A similar situation, but in reverse, is another of the reasons why trains normally cannot run on tram tracks – trams have many track situations (such as the outside rail on very sharp curves, at single blade switches, at large-angled switches and crossings, and various other configurations) where tram wheels also run on their flanges. Train wheel flanges are too deep and too wide for this to work on tram tracks (not to mention that tram curves are often far too sharp for train vehicles to negotiate).

  I said above that trains cannot normally run on tram tracks, and that is generally true. But there were three locations (and possibly more) in Britain where trains did in fact take to the tram tracks. In Glasgow, Huddersfield and Portsmouth, the tramlines had a highly unusual track gauge of 1416 mm (4 ft 7.75 in). This was to permit 1435 mm Standard gauge railway wagons to be operated over parts of the tram system. So why was it necessary to reduce the tram track gauge by 19 mm to allow Standard gauge railway vehicles to run on them?

  As was shown in the first drawing above, railway wheels were too deep and had a back-to-back measurement that was too small to run successfully on (and with the wheel flange within) grooved tram tracks, without the wheel flange riding up on the inside face of the rail groove. By moving the grooved tram rails inwards by 19 mm, and using slightly more shallow grooved rail, it was possible for the railway wagons’ wheel flanges to bear continuously on the bottom of the rail groove, rather than the wheel tread bearing on the rail head (as the trams wheels would). This allowed the railway wagons to be drawn along tramway streets for short distances to access dock railways and the like. But it also meant that the trams, whose smaller profile wheels bore on the rail head, with their flanges inside the groove, had to be gauged accordingly.

  But this is now getting very technical, and really beyond the scope of this book. Nonetheless, I bring up this subject in order to provide some context when we run across those situations where there are minor gauge variations between adjacent railway systems, and why it is possible for some adjacent systems to permit through running while others don’t – it all comes down to that rail-wheel interface.

  As will be seen in later chapters, there are quite a few situations where trains (including light rail) and trams using the same gauge share the same tracks, often called the Karlsruhe model (after the city in Germany which pioneered such integration), something that is more difficult than it may appear on first sight. For this reason, such integration of trams and normal trains (or even light rail) has been much slower than expected, although there now nine or ten systems in the world where such integration has been successful.

  GAUGE CHANGES AND BREAKS OF GAUGE:

  In the previous Chapters, I described a number of times and places where there were different gauges meeting up, and which resulted in whole stretches of railway lines, hundreds of kilometres long in some cases, having to be re-gauged to the prevailing gauge to permit through running of trains. In the Russian Federation and CIS states, a number of lines which were converted to Standard gauge have since been reconverted back to their non-Standard gauge, even though they border with countries using Standard gauge.

  In other parts of the world, particularly in Spain, Japan and Australia, non-Standard gauges also predominate, yet such countries border on other countries or have areas within them, where the ruling gauge is 1435 mm. Thus through running of trains between such countries or areas is not possible – or is it?

  In the past, it certainly wasn’t so. Passengers had to change trains at every such location where two different gauges met – such as in the 19th century at Birmingham and Gloucester, where the GWR broad gauge lines met other companies’ Standard gauge lines, and through running was not possible. At such places, goods and freight had to be manually unloaded from one train and on to another – often a long, laborious and expensive process – while passengers had to disembark from one train and cart themselves and their luggage to the next train.

  Since those days, a number of solutions have been developed to facilitate trains being able to run over trackwork of differing gauges. These solutions can be distilled down into three main systems: 1) Dual- and multi-gauge tracks; 2) changing of vehicle wheel-sets or axles at change of gauge interfaces; and 3) variable gauge wheel-sets or axles. Each is used in various parts of the world.

  Dual- and multi-gauge tracks:

  The use of dual-gauge (and occasionally multi-gauge) trackwork is of course one of the earliest methods of accommodating two different gauges over the same line. It was used for the first time in Britain in the 1860s, when Brunel was forced to start converting the GWR’s lines to Standard gauge. By building many lines as both 1435 mm Standard gauge and his own 2140 mm broad gauge, he was able to hang on to his broad gauge trains for nearly fifty years after the Gauge Act was passed in 1846.

  But while dual-gauge trackwork may have disappeared in the UK when Brunel finally had to come to terms with reality, it can be found in many other parts of the world. It is in fact increasing in usage in those areas where two different gauges meet up, and wholesale changing of existing gauges is unlikely to happen any time soon, if ever. Spain in Western Europe, parts of Eastern Europe, parts of Central and South-East Asia, and Australia, are all countries or areas where a multiplicity of gauges can be found, often side by side. By constructing dual-gauge trackwork, even for short distances, some of the problems of interfacing between these different gauges can be ameliorated.

  There are two primary solutions to building dual-gauge trackwork. The first is to simply add another rail alongside one of the existing rails. This of course – as Hitler discovered to his cost in World War II – can only be accomplished if the two gauges are sufficiently different to allow room for the additional rail.

  Where there is not sufficient difference in gauges to simply add another rail, more complex solutions have to be adopted. The most common is to build two separately gauged lines on the same sleepers, or ties, with the two gauges interlaced with each other. This of course involves the use of four separate rails.

  A little imagination will show that using four interlaced rails can provide more than just two gauges. While not very common, there are a few places in the world where three gauges are to be found, either connecting with, or at least in close proximity to, each other. For example, parts of the Indian sub-continent have instances of Indian gauge (1676 mm), Russian gauge (1520 mm) and Standard gauge (1435 mm) all close to, adjacent to, or even connecting with, each other, and where there is the potential for through running to take place. Can four rails provide these three gauges?

  The following diagram shows how it’s done:

  The same methodology was used in Gladstone, South Australia, involving 1067 mm, 1435 mm and 1600 mm gauges sharing the same trackbed, and again accomplished with four interlaced rails. (Today, only Standard gauge survives – see Part 6.)

  While the use of four rails is a simple solution on plain track, the problems of such multiple gauges integrated with each other occur at switches and crossings. Crossings may not be too bad – just complexity (and potential weakness) in rail spacing a
nd fixings – but the headaches certainly occur at turnouts. Ensuring that the right point blades are set for the right gauge is a real challenge. At some locations (e.g. in Australia), signalling systems detect the gauges of approaching trains and will cause the train to stop if the switches are set for the wrong gauge.

  I do not propose to list what is a rather large number of dual-gauge lines in this Chapter, but instead will describe them as we come to them in our up-coming odyssey around the world (Parts 2 to 7).

  Changing of wheel sets or axles:

  Until relatively recently, changing of bogies at borders where different gauges meet up was the best ‘state of the art’ practice. Although a somewhat drastic approach to coping with gauge changes, it continues extensively to this day, and can be found at many borders, as well as within countries that have more than one gauge, and through running between the gauges is necessary.

  Most of the Russian and CIS countries have bogie-changing stations where their 1520 mm gauge meets Standard gauge – both in the west, at borders with European countries, and in the east, at the borders with China and North Korea. Other places where bogies or wheel sets are (or, in some cases, were) changed include Australia (between that country’s various gauges), Bolivia and Peru in South America (between Standard gauge and a number of narrow gauges), Canada (between Newfoundland’s narrow gauge, recently defunct, and Nova Scotia’s Standard gauge), USA (between competing gauges in various states, long defunct), Finland (between that country’s 1524 mm gauge and the other Scandinavian countries’ Standard gauge), Spain (between Iberian gauge and Standard gauge), and Tunisia in North Africa (between metre-gauge and Standard gauge). These will be covered in more detail in the following respective Parts as we journey around the world.

  Incorporating the easy changing of bogies into the design of, say, a passenger coach usually means that the bogie design must be relatively simple, particularly in terms of how the bogie is attached to the vehicle. Such attachment is rarely more complex than a simple central pivot and very basic side bolsters, with all suspension confined to the bogie itself, and lacking such features as anti-‘hunting’ stability control mechanisms and the like. The very complex and sophisticated bogie and wheel set-ups, usually incorporating advanced suspension and stability systems seen on, say, very high speed vehicles or, especially, tilting trains, are not possible.

  Braking systems are equally simple, as they are connected to the brake operating mechanism attached to the body of the coach or wagon by nothing more than an adjustable rod, with the actual brakes consisting of traditional blocks bearing on the treads of the wheels. More modern systems, where the brake operating mechanism is high pressure and incorporated into the bogie, often operating on multi-rotor disc brakes with anti-lock features, are incompatible with easily changed bogies.

  Consequently, vehicles with easily changed bogies are usually limited in terms of their maximum speed. For example, passenger coaches between China and Russia that form the Trans-Siberian train are limited to a maximum of 120 km/h.

  Bogie changing is primarily confined to non-driven rolling stock. There are a few places where locomotives also can have their bogies changed. This is however generally impractical on a frequent basis – it is usually easier to simply change locomotives, especially as signalling and other standards may be different where bogie changing occurs at international borders. Changing of locomotive bogies is therefore more of a longer term solution, used where a locomotive may need to be transferred from one railway to another, such as in Australia.

  Variable gauge wheel sets or axles:

  Unlike the somewhat drastic approach that comprises the changing of bogies, variable gauge bogies and wheel sets are a much more sophisticated solution. Not only do they eliminate the very time consuming process encountered at bogie-changing stations, but state-of-the-art suspension, braking and stability technology can be incorporated into current variable gauge bogies and axles, thus permitting speeds close to, and in some cases equal to, those obtained with fixed gauge high speed trains.

  There are currently three variable gauge systems in general use:

  Talgo-CAF, a Spanish system that pioneered variable gauge wheel sets. It uses double sided brackets to support the wheels and to facilitate gauge changing, without the use of an axle as such – the wheels are mounted on short stub axles attached to the brackets. The maximum speed with the latest Talgo wheel sets is 350 km/h.

  The Brava system by CAF (now part of Bombardier/Talgo), which moves the wheels sideways on a non-rotating axle a fixed amount. It can be used on both driven and non-driven wheels, and is certified for speeds up to 275 km/h. The changing of gauge is accomplished over a complex mechanism, where the vehicle is supported and guided by support and guide bars, leaving the wheels suspended in mid-air, while their gauge is changed by means of angled guide rails as the vehicle moves forward. This can be effected at up to 30 km/h.

  SUW2000 variable gauge bogies. These are being used successfully between Eastern Europe and the Russian Federation. An illustration with more detail is shown in Part 4.

  One other method of allowing through running, if it can be called that, where breaks of gauge are encountered, is by means of transporter wagons. Generally used as a transfer from Standard gauge to narrow gauge and vice versa, transporter wagons are low platform vehicles on which there are rails set at the alternative gauge (which may be wider or narrower than the wagon’s gauge). At a transfer point, where the alternative gauge rails are elevated to the correct height, wagons are propelled on to the transporter wagon.

  This method is only suitable for 4-wheel vehicles, and of course those have to fit within the narrow gauge loading gauge. It is found primarily in Germany, Austria and Switzerland, and is primarily used to carry Standard gauge vehicles on a narrow gauge railway.

  One exception to this is in Japan, where the Hokkaidō Railway Company is working on a ‘transporter train by trainload’ concept called Train on Train. In a reversal of usual practice, this concept is designed to carry narrow-gauge freight trains at faster speeds on Standard gauge flatcars. It is earmarked for use in the dual 1067/1435 mm gauge Seikan Tunnel (see Part 5), where such freight trains will be able to travel at 200 km/h on the Standard gauge rails, rather than the current 110 km/h limit for a 1067 mm gauge freight train. (This ‘Train on Train’ concept will also permit the Standard gauge Shinkansen gauge trains to travel at 200 km/h in this Tunnel, starting in 2016, rather than their current limit of 140 km/h in order to minimise the side draft impacting a narrow gauge train.)

  I mentioned in a previous chapter that ‘gauge wars’ appear to be being revived, especially between the competing interests of Europe and the CIS, but in other parts of the world as well (Australia’s gauge wars have never really gone away). Perhaps with the advent of state-of-the-art variable gauge wheels, capable of being used on every type of rolling stock, passenger and freight alike, likely to encounter a break of gauge, these gauge wars will eventually subside, and the various entities involved can ‘agree to disagree’ on what gauge is best.

  The only question then is how well such complex variable gauge systems will stand up to long term use, especially in harsh climates over long distances, and suffering varying degrees of neglect and lack of maintenance. That however is a question for the future.

  THE LOADING GAUGE:

  Up to now we’ve talked about the track gauge, which is the main thrust of this book series. But we should also mention another gauge that is also a fundamental part of how railways measure things, and that is what is known as the Loading Gauge. In simple terms, it is the maximum height and the width of the railways’ vehicles, and usually has little to do with the track gauge, other than that ultimately the smaller the track gauge the more limited the loading gauge. I’ve already made a few references to the loading gauge here and there.

  Like many situations when you are the first in the world with something, Britain suffers to this day by being first with a public railway. In the
early 19th century, the first railway vehicles were quite small, reflecting as they did the limited manufacturing capabilities then available, not to mention that most railway vehicles (other than locomotives) were often little more than road vehicles fitted with flanged wheels.

  Consequently, as railways developed in those early days, the lineside structures – stations, signals, over-bridges, tunnels, etc. – were positioned relatively close to the actual trackwork (exacerbated in Britain’s case by the fact that station platforms are high and level with passenger vehicle floors, unlike most other countries, where the platforms are low and well below the projecting body of the passenger cars). Also reflecting the fact that early British railway vehicles didn’t project too much either side of the rails is the fact that the distance between adjacent tracks – sometimes known as the ‘six foot’ – is much narrower than that found in other countries (and a primary reason why the Gauge Commission found in favour of 1435 mm gauge rather than Brunel’s broad gauge – see above). All this limits the physical size of railway vehicles that can travel on Britain’s rails. In fact, Britain’s loading gauge is the smallest in the world for Standard gauge.

  Other countries, whether by design or by accident, constructed their railways with much more space, both between adjacent tracks and between tracks and lineside structures. They therefore can permit physically larger vehicles on their rails, even though the track gauge may be the same as in the UK (1435 mm).

  The constraints of the limited British loading gauge can be exemplified by looking at the American/Canadian locomotives made by EMD or GM seen running on British rails (Class 66, Class 70, etc). They are based on US or Canadian chassis and running gear, but the bodies are entirely different, and sized to fit within the much smaller loading gauge (as well as lower track forces) permitted in the UK. Ironically, today they even travel piggy-back style on top of flat-bed railway cars during shipment to the port where they are loaded on to ships, again reflecting the much larger North American loading gauge (in the past, they used to travel on their own wheels, as shown below).