1015mm

1015 mm (1.015 m) is a dimensional specification equal to approximately 3 ft 3 7⁄8 in. The figure is most often cited as a gauge in the railway industry, representing the distance between the inner faces of the two rails of a narrow‑gauge track. It falls between the 1000 mm (meter gauge) and the 1067 mm (Cape gauge) that have been historically more common worldwide.

The 1015 mm gauge originated in the early twentieth century in several Southeast Asian and Australasian railways where it offered an intermediate solution between meter gauge and the wider Cape gauge. Lines built to this gauge were typically employed for light freight and passenger services on rugged terrain, allowing tighter curves than standard‑gauge sections while maintaining slightly greater capacity than meter gauge.

During the mid‑century, many of the railways that had been constructed to 1015 mm were either converted to standard gauge or dismantled, as standard gauge (1435 mm) became the dominant choice for inter‑regional networks in most countries. Nevertheless, a handful of heritage and industrial rail lines continue to use 1015 mm gauge equipment, preserving a niche of narrow‑gauge operation.

Beyond railways, the numerical value 1015 mm may appear in engineering contexts where a specific length is required—such as the depth of a shaft, the span of a structural beam, or the length of a component in a mechanical assembly. In these applications the figure is usually expressed simply as a metric measurement without reference to gauge.