A Speedwatch campaign carried out in Northampton has clocked dozens of drivers flouting the speed limit.
Volunteers from West Hunsbury stationed themselves at three places along Ladybridge Drive and on Hunsbury Hill Road during April, May and June this year.
Their speed guns detected 89 vehicles travelling at above the speed limit of 30mph. Northamptonshire Police subsequently sent out warning letters to the registered owners of the vehicles.
Although the speeders cannot be prosecuted based on the volunteers' evidence, the monitoring still appeared to have an effect.
A spokeswoman for West Hunsbury Parish Council said: "During the Speedwatch period it seemed evident that the traffic did take some notice as there was a reduction of those exceeding the speed limit during the last week of our campaign compared to the first.
"A traffic survey undertaken on Ladybridge Drive before the Speedwatch initiative recorded 72 per cent of traffic speeding. A second survey undertaken after Speedwatch saw this percentage reduce to 66 per cent."
She added: "We would like to thank the volunteers who took part and would also like to encourage more residents to volunteer next time so that the impact can be greater."
Although drivers caught speeding by Speedwatch volunteers only receive a warning letter initially, their records are held to identify any repeat offenders. Anyone clocking up two or more letters will get a visit from a police officer.
The programme currently has in excess of 600 volunteers trained with others regularly joining the scheme, in 48 places across the county.
To get a Speedwatch scheme in your area, it needs either parish council backing or the support of 20 per cent of the electoral roll.