The material below
is from this page at Roger Farnworth's website -- [rogerfarnworth.com
He seems to be a interested in variety of rr topics; his "Railways" dropdown menu offers these choices --
- French Railways
- The Middle East
- Japanese Railways
- South Africa
- UK Railways
- Model Railway
- Railways Blog
- Uganda and Kenya Railways
"Railways with a track gauge of 3′ 6″ (1,067 mm) were first constructed as horse-drawn wagonways. From the mid-nineteenth century, the 3’6″ gauge became widespread in the British Empire (although it was not used in East Africa or India) and was adopted as a standard in Japan and Taiwan.
There are approximately 112,000 kilometres (70,000 miles) of 1,067 mm gauge track in the world.
. . .
The precise reason why a track gauge of 3′ 6″ in (1,067 mm) (also known as “Cape gauge”) came to be selected as the early standard gauge in Japan remains uncertain. It could be because 3’6″ was supposedly cheaper to build than the international standard “Stephenson gauge” of 4 ft 8 1⁄2 in (1,435 mm), or because the first British agent, whose contract was later cancelled, ordered iron sleepers made for the narrower gauge. It seems most likely, however, that Morel’s previous experience building Cape gauge railways in similar New Zealand terrain was a significant influence, and Cape gauge became the de facto standard.
. . .
It wasn’t until the first high speed Shinkansen line was built in the 1960’s that Japan would finally get a large-scale standard gauge line.