3 ft 6 in gauge railways
（重定向自CAP gauge）
Railways with a track gauge of 3 ft 6 in/1,067 mm were first constructed as horse-drawn wagonways. From the mid-nineteenth century, vast 3 ft 6 in gauge networks emerged in the British colonies and Japan, but 3 ft 6 in gauge tram networks only started appearing in the 20th century.