The UK’s London Underground was originally opened in 1863 for locomotive trains. In 1890, it became the world’s first metro system when electric trains began operating on one of its deep-level tube lines.
It is the world’s third longest metro system, spanning 402km with 270 stations across its 11 lines. Only 45% of the network actually runs underground, mainly in the city centre, with lines in the suburbs mostly running overground.
The network handles approximately five million passengers a day, with as many as 540 trains operating throughout the network at peak times. With increased usage, the network has undergone a number of extensions and upgrades since it was first opened but overcrowding is a common problem across the network.
London Underground has been owned and operated by Transport for London subsidiary London Underground Limited since 2007. Originally, tube lines were owned by various private companies until 1933 when the London Passenger Transport Board was introduced. Ownership of the London Underground was then passed to London Regional Transport in 1984.
Budapest Metro in Hungary first became operational with the opening of Line 1 in May 1896. In 2002, the line was listed as a World Heritage Site by Unesco.
The network comprises four lines. A fifth line to connect the suburban rail system has been proposed but construction has not yet been planned. Lines M1 and M2 were extended in 1973 to their current respective lengths of 4.4km and 10.3km.
Line M3 was opened in 1976, which marked the start of the three lines being colour-coded yellow for M1, red for M2 and blue for M3.
The system features the first automated metro route in Eastern Europe on the M4 line which opened in March 2014. It was estimated that the line would save passengers 14 million hours of travel time each year, as well as lowering the amount of road traffic. While initial planning for the line began in the 1970s, construction did not begin until 2006.
Glasgow Subway in Scotland is the world’s third oldest metro system, opening in December 1896. The system runs along an underground 10.5km loop in the city and is one of the only metros in the world not to have been expanded beyond its original route.
The system carries approximately 13 million passengers every year. It features an outer and inner circle, with services operating the same route in separate tunnels clockwise in the outer circle and anti-clockwise in the inner circle.
Towards the end of the first day of service, an accidental carriage collision caused four injuries and forced the network to close. It reopened on 19 January 1897.
A number of upgrade works are being undertaken across the subway as part of its largest project in 30 years. It includes modernisation of all stations, 17 new trains from Swiss train manufacturer Stadler, and replacement of the ramps and turnouts that allow trains to access the upgraded depot overground.
The Chicago elevated ‘L’ metro system in Illinois, US, began operating as an electrified system in 1897. With 230.2 million passengers in 2017, it is the second busiest metro in the US. There is a 24-hour service available on two lines of the network, which is only featured on four other rapid transit systems in the country.
The network is approximately 165km long with eight lines, which includes a loop in the city centre that services run through or circle to return to their starting point. Tower 18 junction located at the intersection of Lake and Wells in the ‘Loop’ is one of the world’s busiest railway junctions with six of the system’s lines running through it.
Stations in the Loop have undergone a number of changes, with the most recent being the closure of Randolph / Wabash and Madison / Wabash stations, which were replaced with the Washington / Wabash station in August 2017.
In June, the Boring Company secured a contract to expand the network with a high-speed Chicago Express Loop link to O’Hare International Airport.
Paris Métro in France was opened on 19 July 1900. It was one of the first to use the term ‘metro’, which was abbreviated from its original operating company’s name, ‘Compagnie du chemin de fer métropolitain de Paris’. In 2016, Paris Métro had approximately 1.52 billion passengers.
There are 16 lines with 302 stops on the 214km-long network. The average distance between them is 548m and stops are often located within a short walking distance of each other in the city centre. A total of 197km of the network runs underground.
Paris Métro stations are known for their Art Nouveau style and 83 of the original entrances are still in place. Most station interiors were renovated after the Second World War with various redecorations following.
Construction of the metro system began in 1898 with a cut-and-cover method that allowed for the track to be built underground. The lines did not extend to Paris’ inner suburbs until the 1930s with Line 9 terminating at Boulogne-Billancourt in 1934. Planned expansions were put on hold during the Second World War, which resulted in a number of stations being closed.
Massachusetts Bay Transportation Authority (MBTA) operates passenger bus, light and heavy rail services in Boston, Massachusetts, US. Its subway has three main lines and the first electrified rapid transit line, now the Orange Line, was opened in 1901.
Boston Elevated Railway was the original Orange Line before its elevated sections started being demolished in the 1920s. The line was renamed after Metropolitan Transit Authority, later MBTA, took over operations in 1964 and introduced the colour coded system.
The 9.7km Blue Line is the system’s second metro line, which opened in 1904 and is the shortest of the three routes. Plans to extend the line to the city of Lynn have been proposed multiple times since the 1940s but the work has never begun.
The system’s first service was the Green Line, which is a light rail underground system that was opened in 1987 running through the Tremont Street Subway.
The U-Bahn in Berlin, Germany, began operating in 1902 and has since expanded across ten lines with more than 151km of track. Approximately 80% of the lines run underground.
It is estimated that every year trains on U-Bahn travel a total of 132 million kilometres and carried more than 553 million passengers in 2017.
Berlin’s U-Bahn was built as a solution to increasing amounts of traffic around the city and began as an elevated transport link between Stralauer Tor and Zoologischer Garten. The underground network opened in 1910, linking Wilmersdorf with the capital city.
During the First World War, expansion of the network stopped and when it restarted, progress on the U-Bahn was affected by lack of funding. Passenger numbers increased during the Second World War as car use decreased. Some parts of the system suffered from damage caused by bombs and the whole network was shut down in April 1945 following the failure of a power supply system.
Stations in East Berlin were closed following the construction of the Berlin Wall and those on the north-south lines became ‘ghost stations’ as trains were prohibited from stopping at them.
Athens Metro in Greece operates within Greater Athens and East Attica, where it terminates at Athens Airport. The line began operating as an electrified rapid transport system in September 1904, when it was converted from the former Athens-Piraeus Electric Railways, which was opened in 1869.
The system comprises Line 1, which was the original network until Line 2 and Line 3 opened in 2000. The 25.6km-long Line 1 runs mostly over ground and was operated separately to the rest of the city’s transport network until 2011 when the Greek Government created the Athens Mass Transit System to merge services.
Construction on the 17.9km-long Line 2 and 18.1km-long Line 3 began in 1992, aiming to offer alternative transport to car users in an effort to lower pollution levels.
A fourth line has been planned since 2005 and is expected to open in 2026. It will add 33km to the network with 30 new stops. Trains on Line 4 would operate automatically without a driver present.
New York City Subway
The New York City Subway in the US opened in October 1904 with the Interborough Rapid Transit Company (IRT) division, which is now known as the A division, and the Brooklyn-Manhattan Transit Corporation (BMT). When it first opened, a single fare cost $0.05.
It is the largest system in the world by the number of stations, totalling more than 420 stops across 380km. The system handles more than 1.72 billion passengers a year, making it the busiest out of the metro systems in this list and eighth busiest in the world.
There are 36 different lines with 27 services operating on them. Due to the subway operating all day and night, the lines operate across different service patterns and can change while maintenance takes place. The subway has suffered from a backlog of maintenance work since the 1970s when ridership fell as crime and vandalism increased.
One part of the subway being modernised is the signalling system. Originally, vehicles operated using block signalling, which can limit operations due to its lack of precision. Some lines have incorporated communications-based train control (CBTC) signalling, which optimises line usage and allows trains to operate through the blocks at the same time.
Southeastern Pennsylvania Transportation Authority (SEPTA) in Philadelphia, US, operates two rapid transit lines along with four other major public transport services in the city, similar to the MBTA’s operation.
Market-Frankford Line (MFL) is the oldest, having opened in 1907, while Broad Street Line was opened in 1928. Broad Street Line (BSL) operates completely underground apart from the terminus Fern Rock station, while MFL has underground and elevated stations.
The original MFL track split and looped around the foundations of Philadelphia City Hall at the end of the line, but in 1908 the track was extended and redirected underneath the city hall. BSL originally operated from the city hall to Olney Avenue. Since then, it has been expanded to Fern Rock in the north and to the sports and entertainment complex in the south, offering access to the city’s main stadiums and arenas.
The two lines have a combined weekday ridership of more than 310,000 passengers a day and are both approximately 20km long. MFL is the busier line, with more than 185,000 passengers a day.