The Glasgow Subway (Scottish Gaelic: Fo-rèile Ghlaschu, lit. 'Glasgow under-rail') is an underground light metro system in Glasgow, Scotland. Opened on 14 December 1896, it is the third-oldest underground metro system in the world; after the Metropolitan Railway in London (1863) and the Budapest Metro (1896). It is also one of the very few railways in the world with a track running gauge of 4 ft (1,219 mm). Originally a cable railway, the subway was later electrified, but the double-track circular line has never been expanded. The line was originally known as the Glasgow District Subway, and was thus the first mass transit system to be known as a "subway"; it was later renamed Glasgow Subway Railway. In 1936 it was renamed the Glasgow Underground, though many Glaswegians continued to refer to the network as "the Subway". In 2003, the name "Subway" was officially readopted by its operator, Strathclyde Partnership for Transport (SPT).
The system is not the oldest underground railway in Glasgow: that distinction belongs to a three-mile (five-kilometre) section of the Glasgow City and District Railway opened in 1886, now part of the North Clyde Line of the suburban railway network, which runs in a tunnel under the city centre between High Street and west of Charing Cross. Another major section of underground suburban railway line in Glasgow is the Argyle Line, which was formerly part of the Glasgow Central Railway.
The subway system was constructed as a circular loop almost 6+1⁄2 miles (10.5 kilometres) long and extends both north and south of the River Clyde. The tracks have the unusual narrow gauge of 4 ft (1,219 mm) and a nominal tunnel diameter of 11 ft (3.4 m), even smaller than that of the deep-level lines of the London Underground (11 ft 8+1⁄4 in or 3.56 m at their smallest); consequently, the rolling stock for the Glasgow Subway is considerably smaller.
The system is described as two lines, the Outer Circle and Inner Circle, which simply refers to the double track, having trains running clockwise and anticlockwise respectively around the same route in separate tunnels. Stations use a variety of platform layouts including single island platforms, opposing side platforms and in some stations such as Hillhead one side and one island platform.
The subway's running lines are entirely underground, although the maintenance depot at Broomloan Road (located between the Govan and Ibrox stations) is above ground, as was the earlier depot, also at Govan. Prior to modernisation, trains used to be lifted by crane onto and off the tracks for maintenance every ten days. When not running the trains were parked in the tunnels flanking the car sheds. Modernisation brought the installation of points and an access ramp between Govan and Ibrox where trains can exit the tunnel system for maintenance, cleaning, or storage.
Power is supplied to the trains at 600 V DC, using a third rail, via sub-stations at five locations on the circle: Broomloan Depot, Byres Road (Hillhead), Dundasvale (Cowcaddens), Bridge Street and Cornwall Street (Kinning Park). In the event of maintenance or repair work, the system can operate a full service (six trains per circle) with one of the sub-stations inoperative.
The system is owned and operated by the Strathclyde Partnership for Transport (SPT), formerly Strathclyde Passenger Transport, and carried 12.7 million passengers in the period 2019–20. The Subway has been policed by British Transport Police since 2007.
The Glasgow District Subway Company was incorporated by the Glasgow District Subway Act 1890 (53 & 54 Vict. c. clxii), and began construction of the underground in 1891. It opened on 14 December 1896. The subway was powered by a clutch-and-cable system, with one cable for each direction.
The cable was driven from a steam-powered plant between West Street and Shields Road stations. There was no additional cable to allow trains to reach the depot; instead, they were transferred to and from the running lines by crane operating over a pit at the Govan workshops. This also meant that the two tracks could be completely separate, with no points anywhere. The company's headquarters were in the upper rooms at St Enoch subway station; this distinctive ornate building still stands in St Enoch Square and was subsequently used as a travel information office by SPT and is now a coffee shop.
When the Subway first opened, single-carriage four axle (twin truck) trains were operated. Late in the evening on the opening day, after 11 pm, one car laden with 60 passengers was run into by another under the River Clyde. Four people were injured, one being taken to the infirmary. This entailed the closure of the Subway until 19 January 1897. The 20 original wooden bodied carriages were built by the Oldbury Railway Carriage and Wagon Company, of Oldbury, Worcestershire. Many continued in service until 1977 in an upgraded form. A further 10 were delivered by the same manufacturer in 1897. From 1898, second four axle (trailer) carriages without a cable gripper mechanism were added, though they were considerably shorter than the front (gripper) carriage. These additional carriages, eventually numbering 30, were built by Hurst Nelson & Company, Motherwell, Lanarkshire. These carriages were soon expanded to match the length of the front carriages, although carriage 41T has been restored to its original length and cut longitudinally and number 39T is preserved in the Riverside Museum. Most of the gripper carriages were subsequently converted to electric traction in 1935. All carriages were originally built with lattice gates (instead of doors) at the ends; many were converted to air-operated sliding doors in the 1960s, but a few retained the gates until 1977.
All 15 stations were built with island platforms. The trains were thus built with doors on one side only. Power for the electric lighting in the trains was supplied by two parallel wall-mounted rails (known as "T-irons") at window level on the non-platform side of the trains; trains were originally equipped with wheels to pick up the electricity but changed to skids at electrification. The trains remained cable-hauled until 1935, though the anachronistic way of supplying power for the lighting continued until 1977. The lighting circuit was also part of the operation of the signalling system.
Opening times of the Glasgow Subway have varied through the years, now open 06:30 to 23:40 Monday to Saturday and 10:00 to 18:12 on Sunday following a trial period between April 2011 and 2012 when the subway was open from 09:00–18:30.
Glasgow Corporation took over the company in 1923 at a cost of £385,000 (equivalent to £20,100,000 in 2025). In 1935, the existing trains were converted to electric power delivered by a third rail at 600 volts, direct current. From March until December 1935, clockwise trains were cable-hauled, while anti-clockwise ones were electric. The conversion to electric traction cost £120,000 (equivalent to £7,400,000 in 2025). The last cable drawn car service was on 30 November 1935, and was driven by Robert Boyd.
The trains lost their original plum and cream-coloured liveries, being painted red and white instead. From the 1950s the trains became all red—in a shade similar to that of London buses. During the early 1970s, trailer carriage number 41 was repainted in the original 1896 livery.
According to Keith Anderson World War II brought an "unprecedented" level of use by passengers. Anderson attributes this, and an increase in patronage in the years leading up to the conflict, to the expansion of the local shipyard workforce due to the need for rearmament. Unlike its larger counterpart in London the system's stations did not make good air-raid shelters as they were much less deep. On 18 September 1940, during World War II, a German bomb, which dropped during a night raid on Glasgow and may have been intended for nearby naval facilities, landed on a bowling green to the south of Merkland Street station. The resulting explosion caused damage to both tunnels, leading to closure of part of the system until repairs were completed in January 1941. The system suffered no other damage during the conflict. It did lose staff who were called up to participate in the war effort.