#57 Red light camera enforcement

As reported in our previous brief on intersections (Part 1), red light running is a major factor contributing to intersection crashes, which account for approximately 45% of all reported casualty crashes in Victoria and NSW[1]. At signalised intersections, the yellow change interval between green and red lights is critical and should allow drivers to stop safely (sufficient interval) without encouraging them to enter the intersection during the transition phase (excessive interval). While excessive intervals have been associated with intentional red light-running, other factors such as distraction, speeding and impairment are also known contributors.

Red light cameras (RLC) are a common method of enforcement at signalised intersections, but rigorous evaluations of their effectiveness in Australia have been both scarce and inconclusive. A relatively recent systematic review of relevant studies reported interesting results, predominantly from the United States and Australia[2].

Systematic review key findings

The systematic review conducted by Cohn et al. (2020) found statistically significant overall crash reductions in association with RLCs and suggests that RLCs encourage signal compliance. However, while several key crash types are reduced, rear-end crashes were found to increase (see Table), suggesting a potential combination of late braking, tailgating (following too close) and possibly other factors in some instances.

Table 1: Red light camera (RLC) effects by crash type (data: Cohn et al, 2020)

The authors concluded that RLCs are likely to be effective for encouraging compliance and reducing certain types of intersection crashes but may also result in an increase in rear-end crashes. As stated by the authors:

The costs and benefits of RLCs must be considered when implementing RLC programs. The potential benefits of a reduction in traffic violations and in some types of injury crashes must be weighed against the increased risk of other crash types. The economic implications of operating an RLC program also must be considered, including the costs of installation and operation as well as the economic impact of RLC effects.

[1] Austroads Guide to Road Safety Part 2 and (US) FHWA “Intersection Safety”.

[2] Cohn et al. (2020) Red light camera interventions for reducing traffic violations and traffic crashes: A systematic review. Campbell Systematic Reviews 16(2), e1091.