Speed Cameras - Measuring the Impact on Driver Behaviour
D Keenan, FaberMaunsell, UK
A new concept of ?hypothecation? has been piloted by the U.K. Department for Transport, allowing the funds raised from speed cameras to be retained by local authorities and re-invested into further road safety measures. The schemes demonstrated clearly the efficiency and financial benefits available from such an approach, but also highlighted the problems associated with public acceptability and consequently the enforcement of speed limits using speed camera systems.
In some areas, such as in Hartlepool Cleveland, mobile cameras were deployed onto the streets accompanied by clear signs, warning of the potential presence of the cameras along the enforced sections of the network. However, the exact location of the mobile cameras and police operators were not made obvious to the passing motorists. The result was effective enforcement of the speed limits accompanied by a public backlash against the apparent ?profiteering? of the local authority at the expense of the ?unfairly-trapped? motorist.
As a consequence of such reactions, the national hypothecation pilot scheme concluded that cameras should be targeted at accident black spots and overtly deployed onto the streets; that is painted bright colours to make their exact location obvious to passing drivers. This policy is being implemented on camera installations across the United Kingdom.
Speed Control and Accidents The link between reduced speeds and reduced accident frequencies has been clearly demonstrated by previous research (Taylor, Lynam and Kimber, 2000). The results of previous studies are as one would intuitively expect; the faster one drives the more chance there is of an accident occurring and of the accident having serious consequences. In other words for a given road, the faster the traffic flow the greater the accident frequency and severity. In this respect, speed cameras hold potential to improve the accident profiles of a large number of roads.
h4. Government Policy
The UK government has actively promoted and implemented a number of speed reduction measures over recent years in an attempt to improve road casualty rates.
These include the widespread use of road humps, home zones (using chicanes and physical barriers to slow traffic down), the ?THINK!? publicity campaigns and the introduction of 20mph residential zones. However, due to proposed schemes involving large-scale expansion of hypothecation in the UK, the public now perceives speed enforcement cameras as central to current road safety policy.
The aim stated by Lord Whitty at the launch of ?New Directions in Speed Management - A review of policy? (DETR, March 2000) was that ??.by 2010 we want speeding to be as socially unacceptable as drink driving has become.? This will be no mean feat, and given the widespread nature of the speeding problem requires a change in public attitude possibly greater than that experienced towards drink driving in the 70?s and 80?s. At the moment, there is a widening gulf between public and government opinion on speed camera enforcement, spurred on by opposition to cameras in significant elements of the press.
A discrepancy often raised in the debate is that despite an increase in the number of cameras, the overall accident statistics across all roads (i.e. both with and without cameras) haven?t exhibited the expected improvements (?Speed Trap?, Channel 4 Dispatches, 06/07/02). The implication is that the methods being used are ineffective in positively changing driver behaviour, and are thereby not improving road safety.
h4. Research Proposed
The research proposed in this abstract would thoroughly examine the effectiveness of various methods of speed camera enforcement by analysing impacts on driver behaviour and accident statistics, thus allowing conclusions to be drawn about which methods are the most effective.
A significant proportion of the work has already been completed, and was featured in the April 2002 issue of Traffic Engineering and Control magazine, subsequently appearing on national UK television (?Speed Trap?, Channel 4 Dispatches, 06/07/02) and in a number of national newspapers (The Times, The Daily Mail - August 2002). This element of the work was a summary of an MSc. dissertation project, carried out in the summer of 2001 at the Institute for Transport Studies at Leeds University, and measured the spot speeds of a random sample of 4,000 drivers around four contrasting camera sites.
The approach adopted aimed to determine the ?sphere of influence? of speed camera systems, and addressed the question of how they are affecting driver behaviour today, along the routes in question. Previous research had tended to concentrate on trends through time i.e. before and after installation studies or on attitudinal surveys; there seemed to be relatively little work examining the zones of influence of the enforcement systems that are being increasingly used in the UK.
h4. Scope of Study
The sites examined in the MSc. research utilised two different genres of speed camera systems; three using differing arrangements of ?GATSO? cameras, manufactured by SERCO systems, the fourth site in Nottingham using digital speed cameras, manufactured by Speed Check Services (SPECS). The GATSO camera is the older ?grey-box? technology and consists of a wet film camera connected to speed detection equipment focused on a particular point on the highway. The exact location of enforcement is obvious to the passing motorist through the presence of a white painted road scale on the carriageway.
In contrast to this older technology the SPECS digital system has no painted road-scales on the carriageway, and utilises CCTV-style cameras & licence-plate recognition software to monitor vehicle speeds over a measured length of highway. The system was piloted in Nottingham in August 2000. Basic operation is via two cameras mounted above the carriageway; the first reads the number plates of cars entering the link while the second, approximately 1km downstream, reads the plates of vehicles as they exit the controlled link. Computer software then matches up the two plate readings to calculate a measure of average speed derived from the time taken for vehicles to travel between the two cameras.
The work proposed assesses speed camera effectiveness at each site in two ways: 1. Measurement of the speeds of a random sample of 200 drivers at key locations around the speed enforcement systems. For example, at a site using a single GATSO camera, the speeds of 200 cars are measured 500m before, at, and 500m after the camera?s exact location. This allows analysis of variations in speed around the exact location of the systems, and enables determination of the ?zone of influence? of each method of enforcement; 2. Analysis of accident data for time-periods of equal length before and after the installation of the cameras. When considered in conjunction with the speed profiles this ?completes the picture?, illustrating whether the cameras have achieved their objective of reducing accident and road-casualty rates.
Speed surveys and limited analysis of accident trends were performed as part of the original MSc research. Rather than attempting to summarise this here, I would urge that the TEC article is consulted to gain an understanding of the interesting results obtained and range of issues raised. (I can supply by email a PDF version of the TEC article ? please contact firstname.lastname@example.org). At the time of the original work some of the camera systems had only been in place for 1 year, limiting the scope of the accident analysis that was possible. Therefore, in preparation for the AET conference I propose extending the work as follows:
* a) Examination of accident trends over approximately three-year periods before and after camera installation (3-years is a commonly accepted period for accident trends to show a statistically significant change). These time periods are now feasible and the relevant accident data has already been secured from the highway authorities;
* b) Due to the limited scope of available data the accident analysis performed previously only examined the changes in total accident numbers before and after the installation of speed cameras. No analysis was made of changes in accident severities or of changes to the locational pattern of accidents at each site. The updated work will examine both changes in total accident numbers and changes in the killed and seriously injured (KSI) rates often quoted by the government in support of camera schemes;
* c) To analyse spatial trends in accidents the work will also examine plots of accident locations in the times before and after the camera installations. This will allow the changes in accident numbers observed in (b) above, to be explained; finally?.
* d) The isolated GATSO at site 1 of the TEC paper (Scott Hall Road in Leeds) has recently been painted yellow, in line with the UK government?s policy decision to make cameras highly overt. Speed surveys were taken at this site as part of the original research when the camera was grey and less overt; therefore an ideal opportunity exists to isolate and analyse the impact of highly overt deployment on the speed profiles by performing further speed surveys over the coming months, and comparing these to the original profiles. Discussion of the reasons behind highly overt deployment (i.e. public acceptability, etc) and the subsequent impact of this policy on speed profiles at the Scott Hall Road GATSO site will then be possible.
Association for European Transport