A track gauge is the inner distance between two rails on a track designed to accommodate trains, trolleys, and other vehicles which are intended to run on tracks. Like many things around the world, track gauge is not entirely standardized, which can lead to conflicts and confusion. The dominant gauge in use around the world is known as standard gauge, and it measures four feet, eight and a half inches (1,435 millimeters). Many nations including the United States, Great Britain, Mexico, Egypt, Australia, Canada, China, Turkey, Saudi Arabia, Cuba, Norway, Sweden, Finland, Venezuela, Gabon, Spain, Algeria, Morocco, and Uruguay, use this gauge.
As people began to develop vehicles for rail, track gauge was initially highly irregular because people were working and inventing in scattered locations. Within individual nations, gauge could vary by region, and was determined in part by manufacturers of such vehicles. Over time, this proved to be extremely inconvenient. At every break of gauge, where track gauges of different sizes met, obstacles would be encountered. Irregular gauge sizes even led to derailments as vehicles under or overestimated track gauge and thought it was safe to proceed.
As a result, many nations began adopting standard track gauge sizes. The gauge now considered “standard gauge” originated in England, and because many nations used rolling stock shipped from England, they began adopting standard gauge for their tracks. In areas where break of gauge still occurs, gauge conversion may be used to allow vehicles to traverse both sets of tracks; many vehicles have some tolerance and can fit on slightly wider or narrower track.
It is also possible to see dual gauge. In the case of dual track gauge, multiple tracks are laid down together to allow trains of different gauges to travel through the same area. This technique may be used in regions where nations with different standard track gauge sizes border each other. Gauges beyond the standard size are known as broad or narrow gauge, and there are varying reasons for their popularity.
Some model railroad enthusiasts also take track gauge very seriously. If they are trying to keep their trains scrupulously true to scale for a specific time period or region, they will take the time to select the appropriate track gauge and to make modifications, if necessary, to allow their trains to run on it. Accuracy is highly prized among some train enthusiasts, and the attention to detail will be appreciated by fellow fans.