A speed trap set up near Maidenhead's biggest school has caught nearly 30 drivers out in recent months.
Police have been parking in Cranbrook Drive, at the junction with the A308 Furze Platt Road near Furze Platt Senior School, and using a hand-held device to pinpoint offenders.
The speed limit is 30mph at the junction before signs mark the switch to 40mph about 100 yards further up the A308 towards Pinkneys Green.
But a Freedom of Information request on the trap results shows many drivers are putting their foot down as they come up past the school or failing to slow down enough as they travel towards it.
Of the 28 drivers caught between June 1 and September 1, 20 were travelling at 40-45mph.
More than half of those caught speeding - a total of 17 - were doing so between 6-8pm.
The highest speed recorded was 48mph. That driver, and 14 others, received a Fixed Penalty Notice amounting to £90.
Seven were sent on a speed awareness course, and one driver was set to be taken to court.
Four drivers are subject to an 'ongoing process' which means they either failed to respond to the system or have chosen court proceedings.
A police spokesman said speed trap sites are selected based on casualty figures and community concerns.
It is not known how long police spent at the site each day as the time period is not fixed.
Chief Inspector Henry Parsons said: "We're committed to enforcement against the 'fatal four' offences of speed, drink/drug driving, mobile phone use and no seatbelt, because it's shown that targeted enforcement here really does reduce the volume of those killed and seriously injured on the roads."
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