Ms Pidgeon, who is also standing for re-election to the London Assembly, says passengers were “incorrectly charged maximum fares exceeding more than £1m” every week.
The fares are charged when passengers fail to tap their Oyster cards in and out when using buses, trains, Tubes and the DLR.
The figures were released to the Liberal Democrats in response to a Freedom of Information request which the party say Transport for London refused to answer “for over four weeks, breaching requirements of the Freedom of Information Act.”
Pidgeon said: “This level of overcharging is totally unacceptable. There is something very seriously wrong when each and every week Londoners are ripped off by so much.
“Why has Boris Johnson, who has been chair of Transport for London, not taken this seriously in the last four years?
“Of course in some cases passengers might forget to touch in and touch out, but such huge levels of overcharging clearly demonstrate that there are structural problems with how Oyster is operating. We know for a fact that at some stations, especially when the stations are very busy, maximum fares are automatically set for everyone passing through.
“It is time TfL stopped putting all the blame for Oyster overcharging on to passengers and started to recognise that they have a responsibility to ensure honest passengers are not ripped off.
“And where Oyster overcharging does take place it must be far easier for people to claim a refund.”
Commenting on TfL’s slow response to the FOI request Pidgeon added: “TfL should stop treating the level of Oyster overcharging as a state secret. The figures should be regularly published at every station, so that passengers are alerted to this serious problem.”
Candidates for Mayor include Jenny Jones (Green party), Ken Livingstone (Labour), Lawrence Webb (UKIP) Boris Johnson (Conservative) and Brian Paddick (Liberal Democrat). A full list of candidates can be found here.
Candidates standing as London Assembly constituency members can be found here. Candidates for the 11 Assembly London-wide seats can be found here.
