450px-United_Kingdom_40mph_speed_limit_signToday I presented to cabinet the report I chaired, with  the roads and transport policy development panel, on speed limits throughout Suffolk.

We used the government guidance on setting local speed limits as our starting point and put a Suffolk twist on how we should approach changing speed limits locally.

For example, we said

Transport systems play a major part in supporting economic growth but this needs to be in a sustainable and safe way and one that improves the quality of life for communities. A key objective for the Council is to strengthen the Suffolk economy and a Suffolk Growth Strategy has been prepared to achieve that. This indicates that the effective movement of goods and materials and access to training and education are vital for future growth. Speed management including the setting of effective speed limits can support these objectives. Furthermore tourism is identified as an important area and speed limits can support local initiatives including encouraging green tourism by supporting cycling, walking and horse riding.

In deciding upon speed limits lower than the national levels, the criteria to be considered should be the following:

Speed limit – 60mph

  • dual carriageway

  • no facilities – shops, schools etc.

  • only limited frontage development

  • collision history

  • few bends, junctions or accesses

  • individual houses/small group(s) not exceeding 500m overall length

Speed limit – 50mph

  • few facilities – shops, filling station, public house, etc.

  • some frontage development but not necessarily extensive

  • collision history

  • existing traffic speeds

  • few junctions and possibly limited bends and accesses

  • limited pedestrian/cycle activity

  • limited reasons to cross the road

Speed limit – 40mph

  • settlement has shop(s), school(s), public house, filling station, etc.

  • significant development on both sides of road, but not necessarily continuous, with some development in depth, overall frontage exceeds 500m in length

  • collision history

  • existing traffic speeds

  • many junctions, bends and accesses

  • some pedestrian/cycle activity throughout the day with possible peaks associated with schools or community facilities

  • some provision for pedestrians/cyclists or acknowledged need and possibly warning signs

  • lengths of road that more closely fit the conditions for a 50mph limit but where the standard of road/forward visibility is more appropriate to 40mph

Speed limit – 30mph

Urban situation

  • a clear built up area with almost continuous frontage development numerous facilities generating pedestrian/cycle activity – schools, shops, PH, play areas, etc.

  • collision history

  • existing traffic speeds

  • numerous junctions or accesses

  • significant pedestrian activity throughout the day

  • refer to the Suffolk Residential Design Guide *** in relation to new residential developments.

Rural situation – villages

  • A clear village character with 20 or more houses (on one or both sides of road).

  • If just fewer than 20 houses, extra allowance should be made for key buildings such as a church, shop or school.

  • Where the character of a village falls outside this definition, discretion should be used in deciding the appropriate speed limit

  • A normal minimum length for a new speed limit would be 600 metres.

  •  This may be reduced to 400 metres where the density of development over this shorter length exceeds 20 houses and, in exceptional circumstances, it could be reduced to 300 metres.

In respect of village 30 mph limits in some circumstances it might be appropriate to consider an intermediate speed limit of 40 mph prior to the 30 mph terminal speed limit signs at the entrance, in particular where there are outlying houses beyond the village boundary or roads with high approach speeds. For the latter, consideration needs to be given to other speed management measures to support the message of the speed limit and help encourage compliance. Where appropriate, such measures might include signing, centre hatching or other measures that would have the effect of narrowing or changing the nature and appearance of the road.

There may be specific local circumstances where it would be beneficial to introduce lower limits than national levels which do not meet the above criteria. These will need very careful consideration and may include:

  • where there is a particular collision history and a speed limit is part of a remedial scheme which is signed as such

  • where a limit may support an economic development initiative such as in a tourist area and engineering measures are taken to assist enforcement

  • where there is a significant adverse environment impact such as noise or visual intrusion and engineering measures are taken to assist enforcement

  • to achieve a consistency of approach over a particular route

  • at specific locations on national and local cycle networks to assist cyclists

  • at specific locations to promote walking routes.

Furthermore there may be specific local circumstances in relation to Community Speed Watch where small changes to the extent of existing limits are acceptable even if the above criteria are not met. Community Speed Watch in Suffolk is a popular initiative which allows members of the community to address the issue of speeding by becoming actively involved in road safety by monitoring speeds at safe locations with speed detection equipment. It addresses the problem of speeding through the joint work of the police, local community, parish councils and other partners. The aim is not to catch as many speeding drivers as possible but to reduce speed in areas of concern. The use of the speed detection equipment requires a clear forward visibility on 100m from a safe monitoring point. There may be instances where such a distance is not possible to achieve within the existing speed limit terminals and careful consideration will be given to small changes in limits, even if they do not meet the above criteria, to allow speed watch to be undertaken.

In the majority of cases the use of above criteria are considered all that is required to make decisions on the introduction of new speed limits. However where there are more significant and expensive schemes such as route treatments or area wide schemes, then consideration will be given to using the Department for Transport Speed Limit Appraisal Tool which allows a very detailed assessment to support decision making. This is a web based tool which facilitates forecasting changes to speed levels, journey times for business and personal users, vehicle operating cost, accident severity and emissions resulting from the speed limit changes.