#45 How effective are speed cameras?

Enforcement of speed limits using camera technology and other means, and the associated penalties, is one of the more controversial road safety topics in public forums. An Australian study using self-reported data from a large sample of drivers (N=5179) found high levels of acceptance of low-range speeding[1]. According to this study, the extent of speeding tends to increase in higher speed zones, with 48% of participants reporting speeding by up to 10km/h in 100km/h zones. As widely reported in other research, speeding tends to be more prevalent among male drivers and younger and middle-aged drivers.

While camera-based enforcement measures are common in Australia and demonstrably effective in encouraging compliance and reducing crashes, there are many factors that influence specific program effectiveness. A recent study examined these factors to determine which variables had a greater or lesser impact on speed reduction and compliance[2]. The research determined that there is wide variation in the overall effectiveness of camera enforcement.

Benefits

The research by Job (2022) included findings of a previous rigorous review by Elvik, which found 16% and 39% reductions in injury and fatal crashes, respectively, from camera enforcement programs. These reductions were assessed as being conservative estimates, due to these analyses including ‘evaluations of programs weakened by various factors’. Other studies, however, have shown that some implementations have produced more dramatic effects while others have failed to produce statistically significant results.

Considerations

Key factors influencing the effects of speed camera programs, as identified by Job (2022), include:

• The intensity and extent of enforcement camera deployment (number and concentration of cameras across a given section)

• Camera type and visibility (including mobile versus fixed cameras)

• Signage and visibility (clear signs versus ‘covert’ enforcement)

• Extent of speeding at specific sites (where compliance is already high, enforcement is likely to have smaller effects)

• Extent of crash occurrence (as with the extent of speeding, crash reduction is likely to be greater where crash numbers are relatively high)

• Research methods influence findings – studies often focus on a range of different aspects, with varying degrees of rigour applied (e.g., halo effects versus effects at fixed points)

[1] Stephens, A.N., et al., (2017). Self-reported speed compliance and attitudes towards speeding in a representative sample of drivers in Australia. Accident Analysis and Prevention 103, 56-64.

[2] Job, R.F.S. (2022). Evaluations of Speed Camera Interventions Can Deliver a Wide Range of Outcomes: Causes and Policy Implications. Sustainability 14, 1765.