Odd railway gauges

The distance between the two rails of a railway on a normal railway in the United States is 4 feet 8.5 inches. Such a strange measurement basically evolves from the width of two horses’ rears. Imperial Rome built the original cross-country roads in England for their army. They also built war chariots that were just wide enough to contain the rears of two horses for their army. These chariots all were made with the same width between …

…boosters (SRBs). Made by Thiokol in Utah, these SRBs had to be shipped to the launch site via the railway. During its travel to the launch site, the railway ran through a tunnel encompassed by mountains. Because the SRBs had to go through the tunnel and the tunnel is only slightly larger than the width of the railway, the designers of the SRBs had to make them a little smaller than what they had wanted.