Community Speed Watch training on the junction of Goodwins Road and Vancouver Road in King's Lynn. Picture: Ian Burt (Image: Archant 2017)
Community speedwatch campaigners caught more than 40 cars exceeding the limit in just over an hour.
Members of the B1144 Action Group have been trained to use a speed gun.
MORE - residents carry out speed checksThey've been using it to carry out checks along the road from Tennyson Avenue to Vancouver Avenue, in King's Lynn.
After one of their first sessions, they tweeted: 'Community speed watch out this AM 6 - 7.30am on Vancouver Avenue 45 cars exceeding 35mph.'
Drivers caught exceeding the 30mph hour limit by volunteers are not prosecuted but will receive warning letters.
If enough are found speeding, it will trigger full-fledged enforcement action by police.
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