Broadside on railway track

S.Ananthanarayanan

FA&CAO/WCR

Much of railway track in India are on the broad gauge, or 5’6” apart, which is the widest gauge of railway tracks in the world. The standard the world over is 4’ 8.5”. What could be the bases or considerations for deciding on the dimensions of railway track?

Wide gauge is stable.

When the rails are far apart, wagons can be loaded to a greater height and more goods can be carried. Wider tracks also permit greater speeds. These seem to have been the reasons that prompted the Indian Railways to go for the broad gauge in the trunk routes. But in sections where there was not much traffic, the Indian Railways built cheaper track in the metre gauge, or the narrow gauge, where the rails were only 2’ 6” apart.

The Brunel plan

An English engineer called Brunel, who had this great talent of being able to draw a perfect circle, was upset about the ride on British Rail being too bumpy for him to draw circles. As an engineer, he knew that wider wheels would give a smoother ride. So he planned railways that had wheels with a diameter of 12 feet, on tracks 7’ apart. The problem with this design was that the coach would be too high for the passengers to get in and out of.

So Brunel proposed that the carriages be slung low, between the wheels, so that the passengers looked out through the spokes! Maybe it is just as well that Brunel’s idea did not go far, but Burnel did build many wonderful railway lines and bridges all over England and elsewhere in the world.

The standard gauge

The gauge followed all over the USA and in Europe is the standard gauge, 4’ 8.5”. One may wonder at how this became the standard. Was it a careful engineering design, to optimize stability, speed and economy?

Railway historians in USA say the gauge was decided because the wheel-sets that were imported from England were manufactured to this standard. On checking with the industry in England, it turns out that the dimensions were the carry-over from the sizes used for horse-drawn carriages. And why were the wheels of horse-drawn carriages 4’ 8.5” apart? This was because of the mud roads all over Europe. They had ruts that were this distance apart and using any other sizes for wheels would have resulted in accidents. And why these ruts? It turns out that the roads had first been built by the Romans and their chariots had wheels like this.

Well, why on earth did the Roman choose this size? Now we get an engineering answer, at last. The Roman army used a breed of short horse that came from Persia, and to fit two of these horses before the chariot, 4’ 8.5”this turned out to be a comfortable size. Voilà, the reason for the standard gauge!