Northamptonshire Speed Cameras: Post Switch-Off Collision Analysis

  • Published: Road Safety Analysis, 2015
  • Authors: R Owen
  • Date Added: 19 May 2017
  • Last Update: 19 May 2017
  • Format: pdf


The study aims to review the casualty reduction performance of the Northamptonshire sites post-switch off compared to the period immediately prior to April 2011, and to compare these results with the trends for all other Northamptonshire roads.


Information about the location of the cameras was collected from Northamptonshire County Council and site boundaries plotted using a computerised mapping system. Information about collisions was sourced via which provides public access to the official DfT dataset of recorded injury collisions, and the collisions were then matched to the individual camera sites. Finally, the data for the whole of Northamptonshire was obtained from MAST Online which is used by local authorities, police forces and other roads safety organisations to review collision and casualty trends.

Key Findings:

  • Given the significant reduction in collisions immediately following the installation of the cameras up to 15 years before, many would expect collisions to rise again once they were switched off

  • What the results show is the collisions have actually reduced in the post-switch-off period and that the variation in reductions against the Northamptonshire average of all other roads is not significant

  • It could therefore be said that the cameras have continued to ‘work’ despite their inactivity.