Almost two million speeding tickets are being issued to motorists in England and Wales each year, according to Home Office figures.
There are about 6,000 speed cameras in England and Wales
In 2005, the most recent year for which data is available, 1.92 million fines were given - up from 712,000 in 1997.
At £60 per fixed penalty notice, this adds up to an estimated £115.2m a year.
The Tories said motorists were being used as a "cash cow", but the government insisted speed cameras were used to save lives not make money.
The figures were released in response to a parliamentary question, and gave a region-by-region breakdown of the number of fines issued.
In the City of London and Warwickshire, the total has increased about 20-fold since 1997. In Nottinghamshire and Northamptonshire, the rise was about 13-fold.
The number of fines fell in Durham and North Yorkshire, counties which did not take part in the government's speed camera programme.
In 2000, the government created 38 "road safety partnerships" and since then the number of speed cameras has reached about 6,000 in England and Wales.
In 1997, when a fixed-penalty notice was £40, speeding tickets raised an estimated £28.5m.
That bill has increased sharply, in part due to a rise in the cost of a fine to £60 in 2000.
The Department for Transport (DfT) said fines were not central government revenue, but were collected by the court service and passed through the DfT to the safety camera partnerships to be reinvested.
Conservative transport spokeswoman Theresa Villiers said the figures would lead people to wonder whether fines were being used "just to raise revenue".
"Enforcing the law should be the overriding motivation behind speed cameras and penalties. They should not be used just as a cash cow," Ms Villiers said.
"The government needs to rethink ways of improving road safety, including cracking down on uninsured drivers."
The number of road deaths has fallen by 7% since 1998 to 3,172 in 2006.
Vince Yearley, spokesman for the Institute of Advanced Motorists, said: "We believe it should be about compliance rather than capture. Help people drive at the speed limit.
"After all, you don't have to set a speed camera off, so if you know there's one there and you know what the speed limit is you shouldn't have a problem."
Mr Yearley said cameras should be made more visible and speed limits should be posted on camera warning signs so drivers can avoid unwittingly going too fast.
He added: "We should remember, speed is very rarely the cause of a crash, it's an aggravating factor. Cameras can't do anything about the tailgater, the drunk driver or the driver who is distracted and tired."
The Home Office said cameras were targeted at "known accident hot spots" and acted as a "continuous deterrent" without the need for a uniformed presence.
This, it said, freed up police officers to deal with other crimes.
It added that according to the latest figures the proportion of motorists exceeding the 30mph speed limit had continued to fall year-on-year since 1998.
But Paul Smith, of Safe Speed, who is a self-styled campaigner against speed cameras, said more than 28,000 people had signed a Downing Street petition calling for them to be scrapped.
Mr Smith told the Daily Telegraph newspaper: "They have a significant negative impact on road safety - they are actually making matters worse."
But a DfT spokesman said: "Safety cameras are there to save lives, not make money. The best safety camera is the one which takes no fines at all, but succeeds in making everyone slow down.
"Independent research shows a 42% reduction in the number of people killed or seriously injured at camera sites - that means more than 100 fewer deaths each year."