The BBC found that more than 1,200 motorists were caught speeding in less than two months by average speed cameras on part of the M4.
The 50mph cameras were set up along road works between Swindon and Chippenham on 18 March 2013.
There were 261 offences recorded in March and 949 in April and the fastest speed recorded was 107mph.
Avon and Somerset Police said details of incoming revenue was not currently because enforcement had only been in place for a short time.
Inspector Steve Cox, head of road policing for Wiltshire Police, said: ‘Reduced speed limit zones on motorways are in place for a reason and to make that stretch of the motorway as safely as possible while essential maintenance work is undertaken.’
Between April and September 2012, 14,000 motorists were caught speeding on the M4 and M5 near Bristol.
The fastest speed recorded in 2012 was 137mph.