Town councillors in Dorchester are to spend £4,500 on their own speed indicator device to slow drivers down.

The machine, known as a SID, is likely to be switched between two locations – London Road and Herringston Road – although other sites at Maiden Castle Road and near the Trumpet Major pub have also been put forward.

Councillors heard on Monday that a final decision will be made in conjunction with the Dorset Council road safety team who will look at the statistics they record to suggest where the machine might be put to best use.

Said Mayor Cllr Richard Biggs: “We should purchase one to try and improve road safety where we can…it’s a positive message and has proved to be effective,” he told the council’s policy committee.

The town currently has one SID, at Bridport Road, which is operated by Dorset Council as the site qualifies as one of the top ten risk sites for speeding in the rural county.

Town clerk Adrian Stuart said it was likely to be about four months before the additional device was operational as the road safety team would need to vet possible sites and then put up poles to hold the SID.

Cllr Tim Harries welcomed the decision: “After six months this is the first time the two councils have worked successfully together,” he said.

The committee opted for the more expensive version of the machine, which reminds motorists how fast they are travelling and says ‘thank you’ when they are within the limit.

Joe Allen from Dorset Council had previously told town councillors that there was long-sttanding evidence the machines did encouraged driver to slow down; a device recently used in Wool had cut the average speed from 36mph to 31mph.

Town councillors heard that even when the devices are removed and put up at another site drivers maintain a lower average speed on that road for an extra 8-10 weeks. The optimum time for best effect, before moving the machine to another site, is around six weeks.