Road safety and traffic calming
The Police and other authorities use the National Decision-Making model to resolve road safety problems, first identifying the problem, through an evidence-based approach, identifying resolution options and deciding on which options to take followed by reviewing the progress of those actions taken.
Any action taken is based on evidence of the issue and not anecdote with communities needing to obtain evidence through a Community Speed Watch (CSW) scheme.
There is funding for Speed Indicator Devices (SIDS) from a Police fund, based on there being evidence of a speed problem (CSW) however permissions are required from Somerset Highways for them to be installed.
Police/Council speed guidance
The stance of the Police is that they deal with speed as one problem across the County and not as an individual village. They look to maximising the opportunity to alter driver behaviour and therefore will deploy assets (survey cameras and enforcement) where there is potential for the highest volume of offences, thus the greatest opportunity for learning.
In order to achieve their objective and to prioritise resources, deployment is based on an evidenced need. They are often met with the anecdotal narrative the ‘cars speed through the village at 80mph’ or ‘there’s going to be a serious accident’ but require corroborative evidence either through road traffic collision data or speed data in order to justifiably initiate further action. This is both a Police and Somerset Council position.
When analysing speed data the Police/Council utilise an ‘Intervention’ limit. This is calculated at 10% of the speed limit plus 3mph. Therefore, the Intervention limit in a 30mph restriction is 36mph and 25mph in a 20mph zone. This is a national practice agreed by the National Police Chiefs Council and not just applicable to Somerset.
The Police and Council operate to the concept of the 85%ile speed. This is the speed on a stretch of road on which 85% of drivers drive at, or under. It has been developed from considerable research and observation carried out to analyse driver behaviour. It is the highest speed at which most drivers can be considered to be driving sensibly and, in a manner, appropriate to the prevailing conditions. It is not that speeding is tolerated but sets a justifiable criterion on what is considered to be a safe speed in the circumstances. Those drivers in excess of the 85%ile are considered to be less likely to conform to reasonable patterns of behaviour and therefore pay little regard to safety whatever measures are put in place and therefore community lead measures have little effect.
Speed perception
Speed is accurately measured by various approved devices. Individuals can perceive speed differently due to a number of factors. Only Police Officers are considered expert witnesses for speed, and even then, it requires their evidence to be corroborated by equipment or another officer.
Environmental factors can also affect individual perception of speed. These include roads with building in close proximity to the carriageway, size of the vehicle, loudness of engine noise, road noise and a greater volume of traffic increasing the loudness of the engine/road noise, giving the impression of faster speeds.
Speed Indicator Device (SID)
SIDs are temporary vehicle activated signs which detect and display real-time vehicle speeds. They are a method of speed management which aim to change drivers’ speed behaviour. They are an education or awareness tool reminding drivers about speed. There is no enforcement element and no consequence for drivers who speed, other than a frown. As well as indicating speed, they can also provide speed data for analysis. They can be battery or solar powered.
Unless there is a significant accident hotspot, SIDs should not be permanent road fixtures as they are not as effective as when they are rotated around different sites. To maximise their use, SIDs should target specific locations where there is an identified speeding issue.
There is limited information about SIDs effectiveness but what is available suggests that they reduce accidents by 34% and reduce speeds between 2.6 and 7.1mph.
There is a Road Safety Fund available to support with the cost of SIDS. To be able to utilise this, it is necessary to show that there is a speed issue within the area and/or a serious road collision hotspot.
SIDs do have their restrictions. They:
• should be placed on relatively straight stretches of road to allow the radar device to accurately judge speed of approaching vehicles,
• must be fixed to a suitable post,
• must have written approval from residents directly affected by their location,
• can be subject to vandalism,
• can encourage drivers to drive at faster speeds to see what speed they can have them recorded at.
One key consideration is that they should be used with speed as a wider issue and not in isolation. Their use at sites where there is a limited speeding problem lessens their impact at more dangerous/faster locations as they lessen the impact on drivers. Deployment at such sites is not encouraged.
To deploy a SID on the Highway in Somerset, the PC must comply with the Somerset Council’s Policy. This has been re-written in 2024 to provide consistency. The salient points of the policy and requirements are:
• SIDS can only be installed at SC agreed locations. A survey can be conducted on request and at a fee. The PC submits proposed locations for approval with a recommendation of at least 4 sites being identified.
• The SID can only be in a location for a maximum of 2 weeks in a location and not returned to that location for 6 weeks.
• The SID must be an approved device.
• The Parish Council must enter a Memorandum of Understanding before any device can be placed on the highway.
• Additional Indemnity Insurance is required to cover the device and those managing them.
• Previous sites may no longer be suitable, and consideration of safe installation of post and equipment should be studied.
• New posts can be installed on which to fix the SIDS at a cost of approximately £350, depending on size and diameter (usually 89mm). The cost is at the PC expense and once installed they are adopted by Somerset Council.
• SIDs MUST NOT:
o block visibility or be hazard to other road users or pedestrians,
o interfere with street signs, traffic signals or visibility at junctions,
o closer than 45cm from edge of carriageway,
o be less than 2.1m above footway level. Solar panel devices need to be fixed to a 4mtall post,
o be placed on 3rd party apparatus (telegraph pole),
o be erected within 100m of speed terminal sign,
• SIDs should be placed on the left-hand side of the road (as vehicle approaches) to cover a straight-line distance of 200m, as this is a distance that motorists can see the device and adjust their driving behaviour. However, Somerset Council realise this is difficult in rural villages and so set a minimum distance for adequate forward visibility, for effective use of SIDs, of a minimum of 90m in a 30mph area. It does not state what the distance is for 20mph, so it is assumed the minimum distance would remain at 90m.
• SIDs should be placed on the left-hand side of the road (as vehicles approach) and must not obstructed by parked vehicles or overhanging foliage.
• Communities not adhering to the policy and requirements will have the agreement suspended and will not be able to use the SID.
The overall costings provided by Somerset Council are:
o Somerset Council officer to survey and provide advice £250.
o Cost of SID £2500-3500.
o Repair/replacement if SID is damaged or needs replacement.
o Public Liability Insurance for installers to minimum of £5M.
o Annual service and calibration costs.
o Insurance against theft/damage.
o Training costs for persons to manage and move SIDS (Chapter 8) costs £300-500 per person, to be renewed every 5 years.
o Personal Protective Equipment for persons who manage and move the SIDS.
Community Speed Watch (CSW)
CSW is a community-based scheme, where residents monitor traffic speeds to gain traffic data and support the police in identifying and educating drivers who exceed the speed limit. It requires volunteers to run a roadside survey to record vehicles exceeding the Intervention limit (36mph in 30mph limit). The details of these vehicle are provided to the police who write a letter to the registered keeper to advise them of their speed. There is no limit on the number of letters one vehicle can receive and is used to obtain vehicle data and to assist with educating drivers about safe speeds. It requires a coordinator to manage the scheme and liaise with the police and a minimum of 5-6 volunteers with 3 people conducting surveys. One holding the speed gun to measure speeds, one to write down the registration number of vehicles in excess of 36mph and a third to count the number of vehicles.
Establishing a CSW scheme can be a lengthy process but appears necessary to obtain data required for any action.
Road Traffic Collisions
Crashmap.co.uk provides information on road collisions in the area from 1999 to 2022. It uses official data from the Department for Transport. All injury road collisions must be reported to the police, and it is this data that is recorded. It does not include damage only collisions, which may or may not be recorded by the police and the raw data does not provide information as to whether speed was a contributory cause.
The crashmap.co.uk data for South Cadbury does not show any significant risk of injury road collision with only 1 slight injury collision in the past 24 years up to 2022.
7th January 2025