A temporary speed trap at roadworks has led to motorists being fined £750,000 in two months.
Motorists were caught after a reduction in the speed limit
Speed cameras were placed on the A27 at Falmer, East Sussex, while a pedestrian subway was installed.
The speed limit on the road was reduced from 70mph to 40mph and about 12,500 drivers who failed to slow down were fined £60.
The figures appear in the 2003-2004 review of Sussex Safety Camera Partnership, which runs the cameras.
The government-funded organisation made just under £1.5m profit for the year.
Its running costs were £2.1m, while fine revenue for the year was £3.7m, which included the fines for the A27 roadworks.
A spokesman for the partnership said it was "disappointing" that thousands of people were speeding in the county.
"All sites have speed limit reminders and camera symbol signs in advance of the camera and some have flashing vehicle activated signs," he said.
"If drivers and riders are missing all these warnings, what else are they missing on our roads?"
The review also found serious injury crashes and deaths went down by 31% at fixed speed camera sites during the year, and 16% at mobile sites.
A spokesman for the RAC said that 75% of drivers believed speed cameras were just a revenue raising measure.
They worked in a very localised way because when drivers were aware of their location they slowed down then picked up speed once they were past the camera.
"The £750,000 does seem a lot of money and it may suggest that drivers were not aware that the temporary cameras were there," said the spokesman.