The Tanfield Railway is a 4 ft 8+1⁄2 in (1,435 mm) standard gauge heritage railway in Gateshead and County Durham, England. Running on part of a former horse-drawn colliery wooden waggonway, later rope & horse, lastly rope & loco railway. It operates preserved industrial steam locomotives. The railway operates a passenger service every Sunday, plus other days, as well as occasional demonstration coal, goods and mixed trains. The line runs 3 miles (4.8 km) between a southern terminus at East Tanfield, Durham, to a northern terminus at Sunniside, Gateshead. Another station, Andrews House, is situated near the Marley Hill engine shed. A halt also serves the historic site of the Causey Arch. The railway claims it is "the world's oldest railway" because it runs on a section dating from 1725, other parts being in use since 1621.
The railway is run by three bodies: "Friends of Tanfield Railway", "Tanfield Railway Trust" which owns the railway, the locomotives and rolling stock and "The Tanfield Railway Company" which operates the railway.
"The Tanfield Railway Company" is split into four departments; each has a manager and director: Engineering who maintain locomotives, Operations including drivers and guards, Carriage & Waggon who preserve carriages, and Commercial which operates shops, events and the passenger side of operations.