Railway gauge is a path-dependent infrastructure choice. If Brunel had defeated the Stephenson standard in Britain, broad gauge could have become the domestic norm. British engineers and imperial construction would then have carried that norm into American, Canadian, Indian, Australian, and African networks. Once bridges, tunnels, rolling stock, and track were built around it, the cost of conversion would reinforce broad gauge as a global standard.
Notable Point · 54:37-56:06
How a Brunel victory could globalize broad gauge
If Brunel's broad gauge had become Britain's standard, imperial influence and British railway engineering might have spread it across much of the world.