Speed Limits and Review Process

The signed speed limits on the county road network account for one of the greatest causes for public complaint. When requests are received for amendments to speed limits Northamptonshire Highways and Northamptonshire Police undertake a formal review which involves a Panel of relevant officers, chaired by the Road Safety Manager, and includes the Highways Community Liaison Officer for the area in question, the Principal Highways Engineering Officer, safety engineers, road safety practitioners, and the Safer Roads Team Leader for Northamptonshire Police. He has delegated authority from the Chief Constable in speed limit consultations. The Panel is therefore able to provide a consensus decision from both organisations.

In general, we are mindful that determining an appropriate speed limit is not an exact science and can often divide opinion, particularly when the road characteristics and environment change rapidly over relatively short distances. During our monthly meetings, the Panel takes an evidence led approach and evaluates all the available speed, volume and collision data, supporting information, environmental impacts and road characteristics.

In addition, members of the Panel will have visited the identified locations prior to the meeting in order to experience, first-hand, the current restriction in place so as to form an opinion regarding any proposed amendment. The Panel also takes account of a range of other factors, which include, but are not limited to:

  • Criteria and guidance ‘Setting Local Speed Limits’ developed by the Department for Transport (DfT).
  • Association of Chief Police Officers (ACPO) Speed Enforcement Policy Guidelines note: ACPO has now been superseded by the National Police Chiefs Council.
  • What are the realistic prospects of compliance.
  • It should be obvious to a careful and competent motorist why a speed limit is in place and should reflect the function of the road, geometry and environment.
  • A speed limit should seek to reinforce people’s assessment of what is a safe speed to travel to encourage self-compliance.
  • The potential for reducing collisions and casualties in areas with a known history.
  • Any use of traffic calming features must be proportional, aesthetically acceptable and supported by the emergency services.
  • There should be no expectation of the police to provide additional enforcement beyond their routine activity.

It should be noted that this speed assessment process does not imply that speed limits will automatically be reduced. Indeed, in some cases, the assessment may suggest that the existing speed limit may already be inappropriately set too low, and an increased limit could be considered.

For further advice regarding a speed limit review please contact your Highways Community Liaison Officer: 


20mph speed limits

In order to have a meaningful impact Northamptonshire County Council is supportive of 20mph restrictions but generally in areas where vulnerable road users tend to be at risk. This means that the vast majority of new 20mph restrictions in the county are advisory and have been implemented in localised areas outside schools where the traffic calming element is normally in the form of time-specific vehicle activated signs.

We are also supportive of 20mph restrictions in new developments where the road design and infrastructure demonstrates a self-enforcing layout which will clearly achieve effective compliance.

Where requests to reduce existing restrictions are concerned, 20mph limits covering a wider area tend to be contentious, and also more expensive as they generally require physical traffic calming measures in the form of speed humps, raised platforms or chicanes in order to gain compliance. These can often look out of place or have a negative visual impact on a residential environment.

It is also well established that a signed only scheme will have little influence on vehicle speeds, and the police are keen to stress that there should be no expectation on them to provide speed deterrent activity in schemes that should be self-enforcing.

With limited funding available it is also essential that we direct our resources to where they are most needed. We would therefore have some expectation that a speed reduction measure has potential to deliver a collision and casualty reduction benefit. 

The evidence supporting 20mph signed only schemes is inconclusive in terms of the benefits delivered, particularly in relation to the primary objectives of reduced speeds and casualties. The most comprehensive and wide ranging study into the effectiveness of 20mph speed limits was published by the Department for Transport in November 2018. It assesses the outcomes of introducing 20mph speed limit schemes (i.e. reducing speed limits from 30mph to 20mph) in residential areas and town centres. This research provides no clear insight for local authorities into the value or positive changes created by a 20mph scheme. In taking a pragmatic view we therefore remain cautious in terms of implementing 20mph speed restrictions.