Puente Alto-El Volcan Railway, Military railway in San José de Maipo, Chile.

The Puente Alto-El Volcán Railway was a narrow-gauge mountain line that wound through the Maipo Valley near Santiago. Built with a 600-millimeter track width, it navigated steep terrain and tight curves to reach mining operations and remote villages scattered across the landscape.

Authorized after the army stressed its defensive value against Argentina, the 600 mm line was built from 1906 and opened in stages: Puente Alto–El Canelo on 1 March 1910, El Canelo–El Melocotón in 1911, and El Melocotón–El Volcán on 9 June 1914. Regular public use ceased in 1978; the track was closed in 1985 and dismantled by the same drivers who had operated the locomotives.

This railway was vital to the mountain communities, connecting isolated villages to the wider region and enabling trade between the valley and surrounding areas. It shaped daily life for generations of residents who depended on it for both commerce and personal travel.

Much of the route can be explored on foot today, with visible remnants of the original track and infrastructure throughout the valley. Sturdy footwear is essential, as the terrain is uneven and paths may become muddy during the rainy season.

The steam locomotive "La Panchita" and three diesel locomotives were moved to El Melocotón station around 2004, after the Puente Alto Regiment closed. One diesel unit, J-4, has been restored and still pulls short trains for visitors around the station yard, run by volunteers with a former driver as project director.