London Post Office Railway
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The Post Office Railway is a 2 ft narrow gauge, driverless underground railway in London that was built by the Post Office with assistance from the Underground Electric Railways Company of London, to transport mail between sorting offices. Wikipedia
Line length: 6.5 miles (10.5 km)
Closed: 31 May 2003
Depot(s): Mount Pleasant
Loading gauge: Custom gauge
Opened: 3 December 1927
Operating speed: 40 mph (64 km/h) through core tunnels; 7 mph (11 km/h) through stations, platforms and loops
Rolling stock: 1980 Greenwood & Batley