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Speed Indicator Device


The Stonham Parva Parish Council decided to purchase and install two Speed Indicator Devices (SID’s) during 2019. This is based on concerns raised by the village community on speeding through the villages 30 mph zone on the Norwich Road (A140).

The devices record a vehicles speed passing in both directions and flash a speed and message for inbound vehicles. They do not photo or record details of individual vehicles or have any input to local authorities.

Since installation, the devices have proved to be effective at slowing vehicle speeds through the village on the Norwich Road. They were initially deployed in a ‘spy mode’ to establish a benchmark that recorded speeds without a display to drivers thus giving a ‘before’ speed.

When compared with the speeds captured in normal mode, with a speed display, they show a 10% reduction of drivers keeping to the 30mph limit entering the village from the south and a 26% reduction from the north.

The reason these percentage reductions differ is the different circumstances on the Norwich Road (A140) before the devices. To the south of the village there is long stretch of 30-mph zone, a busy junction at the Tap and a hill climb which means drivers have had almost a mile to adjust their speed. However, to the north of the village the device is about 100 yards from the boundary of the 50/30 zone so many drivers are still slowing down.

Daily average traffic volumes in both directions is circa 13,000 or 4.6 million per year. The deployment of these devices means some 830,000 additional vehicles will be doing 30mph or below as a result.

However there are still a number of drivers travelling at much higher speeds than 30, see  the pie charts.  Tragically there has been two fatal accidents over recent months north of the village beyond the 30mph zone. The Parish Council  has asked Suffolk Highways the review and see if there are any additional safety improvements that could be made. We await their response as at May 2020.