OperatorLondon General
GarageWaterloo (RA)
VehicleBYD electric bus / Alexander Dennis Enviro 200
Peak vehicle requirement67
Predecessors501, 508
StartWaterloo station
St Paul's station
Cannon Street
EndLondon Bridge station
Length4.7 miles
FrequencyUp to every 2 minutes
OperatesMon-Fri (Except public holidays)

London Buses route 521 is a Transport for London contracted bus route in London, England. Running between Waterloo and London Bridge stations, it is operated by London General and is one of two Red Arrow branded services. In 2016, it became the first battery electric bus route in London, along with route 507.[1]


See also: Red Arrow (bus)

London General Mercedes-Benz O530 Citaro on Waterloo Bridge in 2013

Route 521 commenced operating on 18 July 1992 as part of the Red Arrow network of bus routes aimed at commuters in Central London linking some of the capital's main railway termini.[2]

On 2 June 2002, along with route 507, the route was the first bus route in London to be converted to articulated bus with Mercedes-Benz O530G Citaros.[3]

During late 2003, early 2004, a series of onboard fires on Mercedes-Benz O530Gs led to withdrawal of the entire fleet, while Mercedes-Benz made some modifications. During this period limited services operated using a variety of different buses on route 521.[4]

In September 2009, as part of the move to replace London's articulated buses, the O530Gs were replaced by Mercedes-Benz O530 Citaros.[5]

Another criticism of articulated buses was the low number of seats, with only 49 per vehicle. A standard rigid Citaro has 44 seats, however the new ones for route 521 have just 21, with room supposedly for up to 76 standers, leading to criticism the new buses were "cattle trucks" and even more crowded than the buses they replaced.[6]

In December 2013, two trial BYD electric buses were introduced.[7] In September 2016, Alexander Dennis Enviro 200 bodied BYD electric buses began to operate the route, making it and route 521 the first battery electric bus routes in London.[1][8][9] In September 2016, the buses on this route and on the 507 have received new digital route displays.[10]

Current route

London General Mercedes-Benz O530G Citaro in August 2004

Route 521 operates via these primary locations:[11]


  1. ^ a b Gillett, Francesca (12 September 2016). "First electric buses in central London 'by end of year' as two routes announced". Evening Standard. Retrieved 13 August 2021.
  2. ^ Dryhurst, Michael (2016). London's Red Arrow Buses. Newcastle: Bowden Publishing. p. 10.
  3. ^ London transport - with a twist BBC News 5 June 2002
  4. ^ "Bendy-buses withdrawn after fires". BBC News. 24 March 2004. Retrieved 5 September 2009.
  5. ^ "The beginning of the end for the bendy bus". Greater London Authority press release. 5 December 2008. Archived from the original on 7 December 2008. Retrieved 5 September 2009.
  6. ^ "Passengers call for the return of the bendy bus". The London Paper. 31 July 2009. Archived from the original on 3 September 2009. Retrieved 5 September 2009.
  7. ^ Electric buses hit London roads The Guardian 19 December 2013
  8. ^ Mayor unveils first fully electric bus routes for central London Transport for London 9 September 2016
  9. ^ "Debut for electrics and StreetDecks" Buses Magazine issue 739 October 2016 page 22
  10. ^ Powell, Tom (12 September 2016). "London buses introduce new 'Tube map-style' digital route displays". Evening Standard. Retrieved 13 September 2016.
  11. ^ Route 521 Map Transport for London