Microsoft word - 2009-12 borders within borders
Borders within borders
The Iberian track gauge of the Spanish railway network (1,668mm between running edges) is different from the standard track gauge of most of the planet's other networks - 1,435mm). In principle, trains cannot pass between two lines with different gauges. Such network ‘borders' have been a long-standing problem for operators and passengers alike. Traditionally this has involved changing trains, an inconvenient and time-consuming process.
In Spain, the points at which different track gauges coexist are found on the French border. There are also borders at some stations since, although the 1,668mm track gauge predominates, Spain's network also has lines with narrower gauges (1,000mm and others), giving rise to other ‘internal borders'. Moreover, the 1988 decision to build new Spanish high-speed lines to the standard track gauge led to the appearance of numerous additional borders - and their associated problems - between the two gauges.
A number of solutions have been tested and implemented in different places at different times. These can be divided into three types. There is the purely non-mechanical process of transferring passengers and goods, coupled with a change of locomotive. More complex is the use of track with three or four rails so that trains of either gauge can operate across networks.
Found in three variants, systems also exist that allow trains - or any of their vehicles - to change gauge. These involve the replacement of axles or complete bogies. The third method, currently in its fourth generation, delivers automatic track gauge change of a vehicle or set of vehicles without interchange of their axles or wheels.
Automatic changeover systems
In the end, it was agreed that the way forward was to implement automatic gauge changeover - an option used successfully since 1969, permitting an increasing number of services and more flexible operating conditions. These systems require fixed installations through which the trains pass as the distance between its wheels is altered. In Spain, they allow trains to move seamlessly from an Iberian gauge track to another of international gauge, or vice versa. In principle, nothing prevents the systems from being adapted to other pairs of track gauges, such as international and ‘Russian gauge' (1,520 mm).
The Spanish system is fascinating to watch. As the train passes through the gauge changer, each vehicle is lifted clear of its wheels and supported by elevated side rails. Locks preventing the wheels from moving along their axles during normal running are
then released. Converging or diverging guides push the wheels into their new position; they are locked in place again and the vehicle lowered back onto them.
The whole operation is performed automatically by means of fixed guides encountered during the train's linear passage through the installation which takes place at low speed (up to 15km/h) without having to stop unless the locomotive also has to be changed. This is a task which has to be performed separately.
Four generations of changers
The common denominator of these first generation changers is that they are only suitable for Talgo trains and only used for hauled vehicles - a change of locomotive is needed when passing from one network to another.
A second generation emerged in response to Spanish high-speed lines having been built to standard track gauge. This gave rise to new gauge borders at points where the high-speed network coincided with lines of conventional Iberian gauge. These gauge changers still require a locomotive change but, when the first loco is detached, the train is moved by gravity with the driver controlling it from the first coach, or with a shunting car.
The arrival of a third generation of gauge changers is linked to the new Madrid-Barcelona high-speed line and overcomes the disadvantages and limitations experienced with the previous incarnations. It has been driven by two developments - the appearance of new gauge change technology - CAF's ‘Brava' system - and the fact that both this and the Talgo system allow traction vehicles (locomotives or self-propelled trains) to pass through the changer. This reduces run-through time and eliminates the need for a pushing locomotive or shunting car.
Several technologies form the basis for the existing automatic systems -
Talgo Variable Gauge (Rodadura Desplazable)
Having been used successfully and without interruption since 1969, this is the world's most ‘experienced' gauge changeover system. Initially applied to Talgo coaches for passenger trains, it has been available for locomotives and power cars since 1999. There are also variable gauge axles that can be installed on freight wagons and their bogies, or in passenger cars.
Used since 2000 in self-propelled diesel and electric trains, including high-speed trains, it can also be applied to other passenger or freight trains.
Polish SUW 2000
This is used on the Poland-Lithuania border and can be applied to passenger cars or freight wagons.
German DBAG/Rafia ‘Typ V'
This German technology has no commercial application at present despite undergoing tests for several years.
A system has been undergoing tests sincethe mid-1990s.
Automatic changeover differences
Whilst conceptually similar, these technologies differ in terms of how the train is supported while the gauge is changed, how the gauge change mechanism is released and how the wheels are secured in the new position. As the changers developed from each technology are incompatible with each other, two operational problems are created: at gauge borders, there would have to be as many changers as there are types of train, giving rise to cost issues as well as a high level of operational complexity; and no train crossing the gauge border can be formed of coaches or wagons of different technologies.
To solve such dilemmas, ‘dual' or ‘versatile' changers have been developed which can be used by trains of two or more technologies. Thus, there is a unique dual changer for the similar Polish and German technologies. In Spain, where Talgo and CAF have coexisted for years, a research and development programme has led to a unification of changers.
The first stage of this process involved designing, patenting and constructing a dual changer which, by means of a fold-away platform, allowed the two trains to pass through. Named TCRS1, this underwent tests at Río Adaja (Valladolid) starting in 2000 and has been in service at Plasencia de Jalón (Zaragoza) since 2003.
The system was immediately improved by introducing simpler and more reliable horizontal movement of platforms. Installation costs were also reduced. Patented by Adif, this changer was used for the first time at Valdestillas (Valladolid) and Madrid Chamartín in December 2007. TCRS3, also patented by Adif in February 2008, will incorporate further design improvements. A prototype is currently under construction and will be installed for tests at Roda de Bará (Tarragona).
Last year, with the need to make gauge changers more versatile and anticipating individual international freight trains comprising wagons of different technologies, a ‘universal changer' was patented by Adif, compatible with Talgo, CAF, Rafia and SUW 2000.
1st June 2009 marked the 40th anniversary of the first gauge changer entering commercial services. In that time, it is estimated that 289,011 passenger-carrying trains have passed through them. The longest-serving changer is the one at Portbou which is also the most used, with 85,309 run-throughs.
My thanks to Yolanda del Val of the Foundation de los Ferrocariles Españoles
for help with the workshop and the compilation of this article.
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