On this page:

Running the Red: An Evaluation of Strathclyde Police's Red Light Camera Initiative - Research Findings

DescriptionThe traffic behavioural study looked at the effect of the red light cameras on the behaviour of drivers at these junctions between 1991 and 1994.
ISBN0 7480 1290 7 (Web Only)
Official Print Publication Date
Website Publication DateJanuary 28, 1999
Development Department Research Programme Research Finding No. 7 (1995)
Running the red an evaluation of Strathclyde Police's red light camera initiative

Mr Ray Winn MVA Consultancy

ISBN 0-7480-1290-7Publisher The Scottish Office
The use of camera technology at signal controlled junctions is designed to reduce the number of accidents caused by non-compliance with traffic signals The camera equipment gathers photographic evidence of vehicles not complying with the red light signal. This evidence is studied by a police officer and offenders are then issued with a conditional offer of Fixed Penalty
The Strathclyde Police red light camera initiative involved the installation of cameras at 6 signal controlled junctions in Glasgow (prior to the implementation of the 1991 Road Traffic Act). The traffic behavioural study looked at the effect of the red light cameras on the behaviour of drivers at these junctions between 1991 and 1994 and at a number of 'control' junctions without cameras. Additionally an analysis of injury road accidents associated with red light running was conducted for the camera junctions.
The Scottish Office commissioned the MVA Consultancy to conduct this work.
Main findings
  • There was a 69% reduction in the total number of red light infringements observed at tine junctions after the cameras became operational.
  • The infringement rate (ie infringements as a percentage of the number of opportunities to infringe) fell from 6.1% to 2.2% after the cameras were installed.
  • There was a significant reduction in the number of more serious infringements ie those which occurred a longer period into the red signal phase.
  • There was a 37% reduction n the total number of red light infringements observed at the control junctions. This was largely due to significant reductions at those control sites located on another approach arm of a camera junction.
  • The cameras had little Impact on the other control sites outwith the areas where cameras are signed and in operation.
  • There was a 62% reduction in the number of injury accidents, where the primary causation was failure to observe a signal, at the camera sites in the three years following the introduction of cameras compared with the three years before.
Red light cameras
The objective of Strathclyde Police's red light camera initiative is to promote road safety and to reduce road accidents associated with non-compliance with traffic signals. An analysis of injury road accident data for Glasgow District in 1992 revealed that red-light running was the primary cause of 17% of accidents at signal controlled junctions and it was a possible contributory factor in a further 8% of accidents.
The 1991 Road Traffic Act enabled the use of automatic detection devices in the enforcement of road traffic law. The red light camera detects red signal infringements by means of inductive loops spaced about one metre apart, with the first being a short distance beyond the approach arm stop line. This system accurately detects the time (into the red phase) of an infringement and the vehicle speed in addition to providing 2 photographs of the offending vehicle. An error in the 1991 Act, however, meant that enforcement measures using the camera evidence could not be employed until this was corrected on 1 April 1993. Prior to this Strathclyde Police issued warning letters to offenders caught on film.
The junctions used in the red light initiative were chosen on the basis of their accident histories. Six junctions within the City of Glasgow had cameras fitted to one arm of the junction in Spring 199O although they did not become operational until late 1991. For the purposes of the evaluation a further six 'non camera control sites were identified for inclusion in the surveys.
Methodology and objectives
The aim of the traffic behavioural study was to evaluate the effectiveness of the cameras in reducing the incidence of red light running and associated accidents. Surveys of traffic behaviour were conducted at the 6 camera sites and the 6 'non camera' control sites. At each survey site an observer collated information on:-
  • the number of opportunities to infringe a red light signal
  • the number of red light infringements
  • the duration and vehicle type of each infringement.
Observations were conducted for a period of 19 hours (7am to 2am) and at the camera sites the camera data was gathered for the same time period.
The surveys were conducted at 3 key stages during the initiative:-

Survey

Date

Key Stage

BeforeSeptember 1991Prior to publicity and signing of the cameras.
InterimMarch 1992Cameras operational, publicity and signing, warning letters issued.
AfterSeptember 1994Cameras fully operational. Fixed Penalty tickets issued to offenders.
The control sites were not included in the "Interim" Survey but were reintroduced for the "After" Survey.
The survey methodology measured changes in driver behaviour caused by the placing of the cameras. Non-compliance, or infringement, was measured against opportunities to infringe' which took account of flow conditions at the junctions. The inclusion of control sites also assisted in interpreting the data, although it must be noted that the control junctions had much lower red light infringement rates than the camera junctions.
Results - camera sites
Number of infringements
Table 1 shows the number of infringements recorded at each of the camera sites for each survey.

Table 1 Number of infringements at camera junctions, observer data

Site

Before

Interim

After

Bridge Street

209

67

88

Garscube Road

113

36

107

Edinburgh Road

97

15

13

Ballater Street

111

54

35

Auldhouse Road

68

10

7

Aikenhead Road

55

21

19

Totals

653

203

269

There was a net 69% reduction in the total number of red light infringements observed at the junctions after the cameras became operational ie between the 'before' and 'interim' surveys. There was however a rise in the number of infringements between the Interim and After Surveys. This was largely due to the Garscube Road site where the number of infringements increased to a level similar to the before survey for reasons which have not been established. (The police camera data for this junction was discounted due to reported problems with the flash unit.)
Infringement rates
Table 2 shows the infringement rates for the camera sites for the 3 survey periods. The infringement rate is the total number of infringements divided by the total number of opportunities to infringe ie it takes account of variable flow or congestion levels at the junctions.

Table 2 Infringement rates at camera junctions, observer data

Site

Before

Interim

After

Bridge Street

6.2%

2.3%

2.6%

Garscube Road

4.9%

1.8%

4.6%

Edinburgh Road

9.7%

1.8%

1.7%

Ballater Street

13.2%

6.1%

3.7%

Auldhouse Road

4.1%

0.8%

0.6%

Aikenhead Road

3.5%

1.4%

1.3%

Totals

6.1%

2.2%

2.7%

The overall infringement rate fell from 6.1% to 2.2% after the cameras became operational. Again the anomaly of Garscube Road affected the After Survey, meaning that there was a slight rise in the infringement rate.
A similar picture was displayed by the police camera data. A 65% reduction in the total number of infringements was observed between the before and interim surveys.

Table 3 Infringements of camera junctions, camera data

Before

Interim

After

All survey sites

278

93

94

The number of infringements recorded by the camera were much lower than the number recorded by the observers. This is because the cameras only recorded infringements after 0.5 seconds into the red phase and for vehicles travelling over 12mph. This ensured that the film in the cameras lasted for the full 19 hour survey period.
Characteristics of red light infringements
The red light infringements were categorised by time band into the red signal phase. Those infringements committed longer into the red phase are more likely to result in an accident at the junction.

Table 4 No of Infringements* by Time Band (Seconds)

Time Band

Before

Interim

After

<0.5

138

48

35

0.5-1.0

197

62

63

1.0-5.0

135

44

52

>5.0

2

3

5

Total Infringements

472

157

155

*using a combination of observer and camera survey data.
The interim results show a significant reduction in the number of infringements in every time band except for those in excess of five seconds. There are significant safety implications in this pattern because the two categories between 0.5 and one second and one second to five seconds fall by 69% and 67% respectively. These are the type of infringements most likely to result in accidents.
Results - control sites
The survey of control sites was only conducted at the 'before' and 'after' stages of the study.

Table 5 Non-compliance at control junctions before and after surveys, observer data

Site

Before

After

No of Infringements (%)

Rate Infringements (%)

No of

Rate

Edinburgh Road*

53

3.7

27

1.8

Auldhouse Road*

38

2.8

5

1.6

Carntynehall Road+

29

2.0

14

1.1

Merrylee Road+

17

1.3

25

2.0

Hyndland Road*

51

4.8

51

4.0

Burnside Drive*

13

2.3

5

0.9

Total

201

2.8

127

1.9

*Arm of junction with camera on different approach arm.

+Junction within the area signed for camera operation.

* Outwith signed area.

Table 5 shows the infringements before and after for the control junctions. All the junctions had a lower overall level of red light running compared to the camera junctions. There was a 37% reduction in the total number of infringements recorded at the control sites between the two survey periods. This decrease was largely due to the 49% and 87% falls in infringements at the Edinburgh Road and Auldhouse Road Junctions, respectively. These two controls were on another approach arm of a camera junction.
Accident data
The central aim of the Strathclyde Police Red Light Initiative is the reduction of accidents caused by traffic signal non-compliance. The survey and camera data has shown that the actual incidence of red light running has been reduced significantly by the presence of cameras. However whether this is translated into a reduction in accidents at junctions requires separate study.
Stats 19 data on injury accidents at the camera sites where the primary causation was failure to observe a signal was collated for the three year period before camera installation and the three year period afterwards.

Figure 1 Injury accidents at camera sites before and after installation

There has been a 62% reduction in the number of injury accidents at the six camera sites. This appears to confirm that the reduction in the incidence of red light running at the camera junctions has been associated with a definite reduction in the accident risk at these junctions.
Summary and conclusions
The installation of cameras at .six junctions in Glasgow had a significant impact on the behaviour of traffic at the junctions concerned.
The traffic behaviour survey showed a 69% reduction in the total number of red light infringements observed at the junctions after the cameras became operational. The introduction of fixed penalty fines for offenders after 1 April 1993 did not appear to have any further impact on the level of compliance.
The survey and camera data showed a significant reduction in the number of infringements committed more than 0.5 seconds into the red phase. This suggests that the cameras are succeeding in reducing the more serious infringements which are associated with increased accident risk. This is confirmed by the accident data for the six camera junctions which reported a 62% decrease in injury accidents, whose primary causation was red light running, after the cameras became operational.
The cameras were successful in altering traffic behaviour at the entire junctions and not just on the approach arm to which they were situated. The control non-camera sites on a different approach arm at a camera junction showed a reduction in the number of infringements after the cameras became operational. The use of cameras did not appear to have any impact on traffic behaviour at junctions outwit the signed area.
Overall the Strathclyde Police red light initiative has achieved its aim in reducing the incidence of red light running and associated road accidents. The findings of the evaluation appear to suggest that the publicity and signing associated with the cameras are important component of the initiative and may have an impact on other junctions within the signed area. Junctions outwith this area, however, were not affected.
" Running the red an evaluation of Strathclyde Police's red lightcamera initiative ", the research report summarised in this Research Findings, may be purchased (price £5 per copy).
Cheques should be made payable to The Stationery Office and addressed to:
The Stationery Office Ltd, Mail Order Department, 71 Lothian Road, Edinburgh, EH3 9AZ.

Telephone: 0131 228 4181 Fax: 0131 622 7017

The report can also be ordered online from:www.thestationeryoffice.co.uk

This Research Findings may be photocopied, or further copies may be obtained from:
The Scottish Office Central Research Unit
Area 2J CRU
Victoria Quay
Edinburgh EH6 6QQ
Tel No: 0131 244 7560

Page updated: Tuesday, June 3, 2008