The original line in 1896

Line 1 is the oldest of the metro lines in Budapest, having been in constant operation since 1896. The line was inaugurated on May 2, 1896, the year of the millennium (the thousandth anniversary of the arrival of the Magyars),^[2] by emperor Franz Joseph. The original name of the operator company was "Franz Joseph Underground Electric Railway Company" ("Ferenc József Földalatti Villamos Vasút Rt.").

The original purpose of the first metro line was to facilitate transport to the Városliget (City Park) along the elegant Andrássy Avenue without building surface transport affecting the streetscape. The National Assembly accepted the metro plan in 1870, and the local Hungarian subsidiary company of the Siemens & Halske AG was commissioned for the construction, starting in 1894. It took 2,000 workers using up-to-date machinery less than two years to complete. The underground part of this section was built entirely from the surface (with the cut-and-cover method).^[3]

The line ran underneath Andrássy Avenue, from Gizella tér station (now Vörösmarty tér station) to Aréna út station (now Hősök tere station). From there it followed an indirect surface alignment through the Városliget to a surface terminus at Artézi fürdő station (now Széchenyi fürdő station). It had eleven stations, nine underground and two on the surface section through the park. The length of the line was 3.7 kilometres (2.3 mi) at that time; trains ran every two minutes. It was able to carry as many as 35,000 people a day (by contrast, today 103,000 people travel on it on a workday).

Diversion at Deák Ferenc tér in the 1950s

In the 1950s and in prepararation for the planned second line of the metro, the route of the line under Deák Ferenc square was diverted in order to ease the sharp curve that had been dictated by the original layout of the square. The diversion left an 80 metres (262 ft 6 in) long section of the original tunnel empty and walled off, a state it was left in for some twenty years.^[4]

Extension and reconstruction in the 1970s

Map of the 1973 diversion

Between 1970 and 1973 the line underwent an extension and reconstruction of some sections. The most significant was the extension to Mexikói út. This involved the closure of the surface alignment through the Városliget, including both Állatkert and Széchenyi fürdő surface stations. In its place a new underground alignment was adopted, passing below the Városliget and serving a new underground through station at Széchenyi fürdő. Állatkert station was not replaced.^[5][6]

At the same time Deák Ferenc tér station was rebuilt to connect with the M2 line, and the rolling stock was changed to Ganz MFAV multiple units, which still operate on the line, and the line’s left-hand traffic was changed into right-hand traffic. In line with the rebuilding of Deák Ferenc tér station, the section of tunnel abandoned some 20 years earlier was rebuilt to house the Underground Railway Museum, with access from the new station concourse.^[4][7]

Renovation in 1995

During the past hundred years, none of the renovations touched the tunnel section under Andrássy út. As a result, the infrastructure of the tunnel (the masonry, the load-bearing steel structures, the water insulation, the railway tracks, the architecture of the stations) hadn’t changed at all or very little. From the middle of the 1980s, they started to show their age, and the serious damage and wear and tear prompted the necessity and urgency of a reconstruction. Renovation works took place during a planned closure between 15 and 18 September 1995.

Possible extension to Rákosrendező

As part of a new luxury development project at the Rákosrendező railway station, known as "Millenium City Center" or "Maxi-Dubai", the M1 line would be extended north from the current terminus at Mexikói út to provide better transportation links to the new site. It would serve brand-new apartments, office buildings, commercial properties, and what János Lázár, Hungary's Minister of Construction and Investment, labeled "Budapest's largest and most modern public park." It would also include a renovation of the existing railway station as well as a new pedestrian & cycle path to make it easier to access the new development center.^[8][9]

From 1896 to 1973

Original rolling stock in special service

The line opened with 20 electrically powered motor cars built by the Hungarian subsidiary of Siemens and Halske. Cars 1 to 10 were panelled in sheet metal, whilst cars 11 to 19 were wood panelled, and No. 20 was a special design “Emperor’s Car”. Because of the low headroom available in the line's tunnels, the cars had an extremely low profile, and the operator had to squeeze into a very tight cab. The cars had drop centres for the doors a single pocket door on each side, and the seats were above the trucks. The cars could reach a top speed of 17 miles per hour (27.4 km/h).^[10]

As originally built, the motor cars ran singly. But in 1959 to 1960, 16 four-wheel control trailers were built to run with them and provide extra capacity.

The cars, both motor and trailer, were retired from normal service by 1973. One of the original wood panelled cars is maintained in working order and is occasionally used on special services. One of each of the metal and wood panelled cars, and one of the trailers, are exhibited in the Underground Railway Museum, itself fashioned from the original Deák Ferenc tér station. Other cars have been preserved elsewhere, including one at the Seashore Trolley Museum at Kennebunkport in the US state of Maine.^[7][10][11]

From 1971 to present

Ganz MFAC car at Mexikói út

With the extension and reconstruction of the line in the 1970s, new Ganz MFAV cars were built in Budapest by Ganz Works to replace the original rolling stock. These cars are eight-axle articulated vehicles. Each unit has with 3 sections, each having 2 doors per side, with no internal connection between. The driver’s cabs are located above the end bogies and can only be entered from a small door on each side. The loading gauge constraints of the line meant that all electrical subsystems are fitted above the articulations, between the separate passenger compartments.

In total 23 cars were built, comprising two prototypes in 1971, 19 production cars in 1971 to 1973, and two further cars in 1987 although originally two more were to be purchased at this time. All are still in service.