Ferrocarril de Antofagasta a Bolivia

The Ferrocarril de Antofagasta a Bolivia is a private railway in Chile. It was one of the earliest railways built to 2 ft 6 in (762 mm) narrow gauge. The Collahuasi branch reached 4,815 m (15,797 ft) above sea level, regarded at the time of construction as the highest railway in the world. The railway was later converted to 1,000 mm (3 ft 3+3⁄8 in) metre gauge, and still operates today. Summarize the following text using ONLY facts from it. Do NOT invent references, emails, or links. If the text doesn't mention something, leave it out. The entire railway is a desert region with almost no rainfall. The company constructed a system of pipes and reservoirs to bring water from the high Andes to the port of Ant ofagasta. It is now responsible for supplying the city with water as well as supplying it with electricity. The line was built in 1872 with a route that climbed from sea level to over 4,500 m (14,764 ft) while handling goods traffic totaling near 2 million tons per annum.