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What was the Broad Gauge ?

Travel by train in Britain today and, on most railways, you will be travelling on rails 4 feet 8½ inches (1435mm) apart.  But back in the 1830s, when our railway network was starting to be built, there was no “standard gauge”.  Isambard Kingdom Brunel, the young engineer to the Great Western Railway (GWR), decided to use rails that were about 7 feet apart, as he felt this would allow him to build a better railway.

With the wheels further apart there would be more space to fit boilers between them.  On the 4 feet 8½ inch gauge favoured by other engineers such as George and Robert Stephenson, boilers had to be mounted higher, or kept smaller.

The wider gauge would also allow carriages and goods wagons to be built with the body between the wheels, which would result in a lower centre of gravity so they would run more steadily and safely.

In practice though, few were built in this fashion, but instead, they were built wider, and so could carry more goods or passengers in shorter – and therefore lighter – trains.

Brunel also reasoned that wheels mounted outside of boilers or carriage bodies could be larger which would create less friction and make his trains run more freely.

But while Brunel was building his novel railway from London to Bristol, there was a huge network of narrower lines being built in other parts of the country.  In 1845, four years after the GWR was completed, a Gauge Commission was created to report on whether all railways should be built to "one uniform gauge".

Several witnesses to the Commission thought that a gauge somewhere between the two gauges would be best.  Brunel however, stated that he would consider an even wider gauge if he was starting again.  He also accepted that there was a place for the narrower gauge for certain railways, indeed he used it for the coal-carrying Taff Vale Railway.  He suggested that locomotive trials should be conducted to compare the merits of the two gauges.

The broad gauge tests were carried out between London and Didcot, and the locomotives proved to be able to pull heavier loads at higher speeds than their narrow gauge counterparts.  They also stayed on the tracks, unlike one of the narrow locomotives !

Despite the outcome of these tests, the Gauge Commission declared that 4 feet 8½ inches would become the standard, mainly because 87% of railways had already been built to that gauge.  Standard gauge was also cheaper to construct, and conversion from broad to narrow easier to carry out, as no additional track bed widening would be required.