Should traffic enforcement be unpredictable? The case of red light cameras in Edmonton

Red light cameras are installed in many jurisdictions around the world to improve road safety by discouraging red light running behaviour at signalized intersections. In many jurisdictions, a smaller number of cameras are rotated among a larger number of locations to increase the effectiveness of the red light camera programs. This study outlines some arguments for deciding the best deployment strategy that can be used to rotate these cameras, focusing on the deterrent effects of enforcement and punishment on driver behaviour. A simple on-road experiment is then conducted to determine the effectiveness of three different rotation schemes. Our results suggest that not moving the cameras and keeping enforcement predictable yields a lower average violation rate than moving the cameras around and making enforcement uncertain.     

Evaluation of red light camera enforcement in Oxnard, California

Red light cameras are increasingly being used to supplement police efforts to enforce against noncompliance with traffic signals--a substantial contributing factor in urban motor vehicle crashes. Camera enforcement is intended to modify driver behavior through both general deterrence and punishment of individual violators. A before/after quasi-experimental design with controls was employed to evaluate the influence of a red light camera enforcement program on red light violation rates in the city of Oxnard, CA. A total of 14 intersections (nine camera sites, three non-camera sites, and two control sites) were studied. Overall, the red light violation rate was reduced approximately 42% several months after the enforcement program began. Increases in driver compliance with red lights were not limited to the camera-equipped intersections but spilled over to nonequipped intersections as well. Results of public opinion surveys conducted approximately 6 weeks before, 6 weeks after, and 6 months after the camera enforcement program began indicated that nearly 80% of Oxnard residents support using red light cameras as a supplement to police efforts to enforce traffic signal laws.     

The impact of red light cameras on safety in Arizona

Red light cameras (RLCs) have been used in a number of US cities to yield a demonstrable reduction in red light violations; however, evaluating their impact on safety (crashes) has been relatively more difficult. Accurately estimating the safety impacts of RLCs is challenging for several reasons. First, many safety related factors are uncontrolled and/or confounded during the periods of observation. Second, “spillover” effects caused by drivers reacting to non-RLC equipped intersections and approaches can make the selection of comparison sites difficult. Third, sites selected for RLC installation may not be selected randomly, and as a result may suffer from the regression to the mean bias. Finally, crash severity and resulting costs need to be considered in order to fully understand the safety impacts of RLCs.

Recognizing these challenges, a study was conducted to estimate the safety impacts of RLCs on traffic crashes at signalized intersections in the cities of Phoenix and Scottsdale, Arizona. Twenty-four RLC equipped intersections in both cities are examined in detail and conclusions are drawn. Four different evaluation methodologies were employed to cope with the technical challenges described in this paper and to assess the sensitivity of results based on analytical assumptions. The evaluation results indicated that both Phoenix and Scottsdale are operating cost-effective installations of RLCs: however, the variability in RLC effectiveness within jurisdictions is larger in Phoenix. Consistent with findings in other regions, angle and left-turn crashes are reduced in general, while rear-end crashes tend to increase as a result of RLCs.     

A before-and-after study of driver stopping propensity at red light camera intersections

This paper reports a before-and-after study which evaluated the impacts of installing and operating red light cameras at two "T" and one "X" signalized intersections on driver stopping propensity upon the onset of amber. Rather than using video cameras, a special purpose data logger working in conjunction with loop sensors was used to gather traffic parameters, vehicle stopping/crossing movements, and signal phases. Logistic modeling was employed to model the revealed stopping/crossing decisions of non-platoon vehicle drivers in response to the onset of amber with traffic, situational and behavioral variables, including their interactions. The results indicate that the variable Cam_Inst that gathered the impacts of red light camera (RLC) installation on driver decision-making at signalized intersection was significant at 5% level only for the camera approach model of the cross-intersection. The significance of Cam_Inst was undermined for the camera approaches at the T-intersections by the inclusion of a significant two-order variable defining the interaction of Cam_Inst with distance from the stop-line. One may, thus, infer that RLC has a fixed-quantum effect at the cross-intersection, but an accentuated effect with distance at the two T-intersections. Lastly, the effects of a RLC at an intersection on the stopping decision at the non-camera approaches were minimal.     

Still red light for red light cameras? An update

The present study has replicated the results from a previous meta-analysis by Erke (2009) [Erke, A., 2009. Red light for red-light cameras? A meta-analysis of the effects of red-light cameras on crashes. Accident Analysis & Prevention 41 (5), 897–905.] based on a larger sample of RLC-studies, and provides answers to the criticisms that were raised by Lund et al. (2009) [Lund, A.K., Kyrychenko, S.Y., Retting, R.A., 2009. Caution: a comment on Alena Erke's red light for red-light cameras? A meta-analysis of the effects of red-light cameras on crashes. Accident Analysis and Prevention 41, 895–896.] against the previous meta-analysis. The addition of recent studies to the meta-analysis and a more thorough investigation of potential moderator variables lead to a slight improvement of the estimated effects of RLC in the previous meta-analysis. The present study found a non-significant increase of all crashes by 6% and a non-significant decrease of all injury crashes by 13%. Right-angle collisions were found to decrease by 13% and rear-end collisions were found to increase by 39%. For right-angle injury collisions a decrease by 33% was found and for rear-end injury collisions a smaller increase was found (+19%). The effects of RLC are likely to be more favorable when RLC-warning signs are set up at main entrances to areas with RLC enforcement than when each RLC-intersection is signposted. The effects of RLC may become more favorable over time, this could however not be investigated empirically. Several results indicate that spillover effects may occur for right-angle collisions, but most likely not for rear-end and other crashes. If spillover effects do not occur for rear-end crashes, which increase at RLC intersection, this would be a positive result for RLC. However, the results seem to be affected to some degree by publication bias and the effects may therefore be somewhat less favorable than indicated by the results from meta-analysis.     

Characterizing red light runners following implementation of a photo enforcement program

Red light running causes about 260,000 crashes and 750 fatalities each year in the US (Retting, Ulmer, & Williams, 1999, Accident Analysis & Prevention). This study investigated the effects of photo enforcement cameras on reducing red light running and characterized the typical red light runner throughout photo enforcement program implementation. In Southeast Virginia, eight intersections were observed over an 8-month period during which photo enforcement cameras were installed at three sites. To assess spillover effects, three other sites served in a same city comparison group. Two additional sites from a nearby city served in a control group for city. Over 1750 light cycles were observed with red light running occurring at least once during 13% of these cycles. Predictors of red light runners included being at a site without a camera or at an intersection before deployment of cameras, being under the age of 26, being in the non-camera city, not using a safety belt, and driving in more traffic. While overall red light running decreased at camera sites, characteristics of the typical red light runner remained the same at camera and non-camera locations.     

An evaluation of Winnipeg's photo enforcement safety program: Results of time series analyses and an intersection camera experiment

The objective of this study was to evaluate the impact of Winnipeg's photo enforcement safety program on speeding, i.e., “speed on green”, and red-light running behavior at intersections as well as on crashes resulting from these behaviors. ARIMA time series analyses regarding crashes related to red-light running (right-angle crashes and rear-end crashes) and crashes related to speeding (injury crashes and property damage only crashes) occurring at intersections were conducted using monthly crash counts from 1994 to 2008. A quasi-experimental intersection camera experiment was also conducted using roadside data on speeding and red-light running behavior at intersections. These data were analyzed using logistic regression analysis. The time series analyses showed that for crashes related to red-light running, there had been a 46% decrease in right-angle crashes at camera intersections, but that there had also been an initial 42% increase in rear-end crashes. For crashes related to speeding, analyses revealed that the installation of cameras was not associated with increases or decreases in crashes. Results of the intersection camera experiment show that there were significantly fewer red light running violations at intersections after installation of cameras and that photo enforcement had a protective effect on speeding behavior at intersections. However, the data also suggest photo enforcement may be less effective in preventing serious speeding violations at intersections. Overall, Winnipeg's photo enforcement safety program had a positive net effect on traffic safety. Results from both the ARIMA time series and the quasi-experimental design corroborate one another. However, the protective effect of photo enforcement is not equally pronounced across different conditions so further monitoring is required to improve the delivery of this measure. Results from this study as well as limitations are discussed.     

Willingness to pay for private and public road safety in stated preference studies: Why the difference?

Estimates of the willingness to pay (WTP) for a mortality risk reduction can be used to calculate the value of a statistical life, which is a major component in many economic evaluations of environmental and safety policies. Previous research on the WTP for risk reductions using stated preference methods have found that the mean WTP for public risk reductions is significantly smaller compared to the mean WTP for private risk reductions of equal magnitude. Hence, the use of a private or public scenario in stated preference studies of e.g. environmental or safety policies may strongly determine the outcome of the economic evaluation. In this paper we use a stated preference survey to show that WTP for a private risk reduction is three times higher compared to a public risk reduction and a significant part of the difference can be explained by respondents’ attitudes towards privately and publicly provided goods in general.     

Evaluation of automated speed enforcement on Loop 101 freeway in Scottsdale, Arizona

Speed cameras can reduce speeding and injury crashes, but in many communities they are confined to low-speed settings such as residential streets and school zones. In 2006 the city of Scottsdale, Arizona, implemented a 9-month pilot program to evaluate the feasibility and effects of highly visible speed camera enforcement on a busy urban freeway. This was the first use of fixed speed cameras on a major US highway. Deployment of six cameras along an 8-mile corridor was associated with large declines in mean speeds and an 88% decrease in the odds of vehicles traveling 11 mph or more above the 65 mph limit. Traffic speeds increased soon after the pilot program was suspended. In addition to reducing speeding along the enforcement corridor, speed cameras were associated with large reductions in speeding on the same highway but 25 miles away from the camera installations. However, traffic speeds were fairly stable on urban freeways in Scottsdale that were not part of the study road. Public opinion surveys found widespread concerns about speeding on the Loop 101 freeway and high levels of support for speed camera enforcement on this road.     

Use of CCTV to determine road accident factors in urban areas

This paper sets out to assess whether there is a potential use for images collected through the increasingly ubiquitous use of CCTV cameras in urban areas as a means of increasing understanding of the causes of road traffic accidents. Information on causation and contributory factors is essential as a means of understanding why accidents occurred and how the occurrence of similar events may be prevented in the future. CCTV records of accidents could provide an independent perspective on an accident and have the potential to increase both the quality and quantity of information available to the safety researcher.

This study focuses on an area of central Leeds in the UK and shows that an existing CCTV camera system used for urban traffic management reasons has the potential to record around a quarter of the accidents which occur in the area, based on patterns of past occurrence. Most city centres in the UK will have similar camera systems set-up. By the introduction of additional strategically placed cameras and replacement of existing cameras with ones dedicated to accident recording, this figure could be increased substantially.

The paper also considers how effective cameras and video records will be as a means of identifying contributory factor information once an accident is recorded. The contributory factor classification used by a recently introduced system in Britain is assessed in terms of how visible each of the factors is likely to be on video and their relative frequency of occurrence. It is concluded that CCTV has a high potential to provide corroborative evidence about many of the most commonly occurring factors, and to throw further light on accident causation.     

Reducing red light running through longer yellow signal timing and red light camera enforcement: results of a field investigation

Red light running is estimated to account for 900 intersection crash fatalities annually. Two principal methods used to reduce red light running involve lengthening the duration of yellow change intervals and automated red light enforcement. The present study evaluated the incremental effects on red light running of first lengthening yellow signal timing, followed by the introduction of red light cameras. At six approaches to two intersections in Philadelphia, Pennsylvania, yellow change intervals were increased by about 1s, followed several months later by red light camera enforcement. The number of red light violations was monitored before changes were implemented, several weeks after yellow timing changes were made, and about 1 year after commencement of red light camera enforcement. Similar observations were conducted at three comparison intersections in a neighboring state where red light cameras were not used and yellow timing remained constant. Results showed that yellow timing changes reduced red light violations by 36%. The addition of red light camera enforcement further reduced red light violations by 96% beyond levels achieved by the longer yellow timing. This study shows that the provision of adequate yellow signal timing reduces red light running, but longer yellow timing alone does not eliminate the need for better enforcement, which can be provided effectively by red light cameras.     

The use of maintenance indicators to evaluate the effects of maintenance programs on NPP performance and safety

Nuclear Power Plants (NPPs) under commercial operation are under continuous demand to meet higher levels of performance and safety by NPP owners, regulatory authorities and the public in general. Maintenance plays an important role in achieving such a goal, therefore, many programs are being conducted in order to improve their effectiveness. A common link between these programs is the necessity to evaluate how maintenance affects NPP performance and safety. This paper presents the foundation of a methodology for a maintenance evaluation program based on maintenance indicators and how it is applied to monitoring the effectiveness of the maintenance at the Cofrentes NPP. The methodology is general and might be applied in other fields of industrial engineering, particularly in those activities which devote many resources to maintain plant equipment, and also in those with less but very critical maintenance.     

The red-light running behavior of electric bike riders and cyclists at urban intersections in China: An observational study

Electric bikes and regular bicycles play an important role in the urban transportation system of China. Red-light running is a type of highly dangerous behavior of two-wheeled riders. The main purpose of this study was to investigate the rate, associated factors, and behavior characteristics of two-wheelers’ red-light running in China. A field observational study was conducted using two synchronized video cameras at three signalized intersections in Beijing. A total of 451 two-wheelers facing a red light (222 e-bike riders and 229 cyclists) were observed and analyzed. The results showed that 56% of the two-wheelers crossed the intersection against a red light. Age was found to be a significant variable for predicting red-light runners, with the young and middle-aged riders being more likely than the old ones to run against a red light. The logistic regression analysis also indicated that the probability of a rider running a red light was higher when she or he was alone, when there were fewer riders waiting, and when there were riders already crossing on red. Further analysis of crossing behavior revealed that the majority of red-light running occurred in the early and late stages of a red-light cycle. Two-wheelers’ crossing behavior was categorized into three distinct types: law-obeying (44%), risk-taking (31%) and opportunistic (25%). Males were more likely to act in a risk-taking manner than females, and so were the young and middle-aged riders than the old ones. These findings provide valuable insights in understanding two-wheelers’ red-light running behaviors, and their implications in improving road safety were discussed.     

Contrast enhancement for in vivo visible reflectance imaging of tissue oxygenation

Results are presented illustrating a straightforward algorithm to be used for real-time monitoring of oxygenation levels in blood cells and tissue based on the visible spectrum of hemoglobin. Absorbance images obtained from the visible reflection of white light through separate red and blue bandpass filters recorded by monochrome charge-coupled devices (CCDs) are combined to create enhanced images that suggest a quantitative correlation between the degree of oxygenated and deoxygenated hemoglobin in red blood cells. The filter bandpass regions are chosen specifically to mimic the color response of commercial 3-CCD cameras, representative of detectors with which the operating room laparoscopic tower systems are equipped. Adaptation of this filter approach is demonstrated for laparoscopic donor nephrectomies in which images are analyzed in terms of real-time in vivo monitoring of tissue oxygenation.     

Red light for red-light cameras?: A meta-analysis of the effects of red-light cameras on crashes

A meta-analysis has been conducted on the effects of red-light cameras (RLCs) on intersection crashes. The size and direction of results reported from studies included in the meta-analysis are strongly affected by study methodology. The studies that have controlled for most confounding factors yield the least favourable results. Based on these studies, installation of RLCs leads to an overall increase in the number of crashes by about 15%. Rear-end collisions increase by about 40% and right angle collisions, which are the target crashes for RLC, are reduced by about 10%. All effects are, however, non-significant. Meta-regression analysis shows that results are more favourable when there is a lack of control for regression to the mean (RTM). An interaction is found between control for RTM and control for those spillover effects that result from the tendency of RLCs to affect crash levels in nearby intersections without RLC. In studies controlling for RTM, additional control for spillover effects reduces the favourability of results still further. Studies controlling for both RTM and spillover effects tend also to control for more additional factors than other studies. It is likely that the results are affected by additional moderator variables, which could not be investigated in this meta-analysis. RLCs may reduce crashes under some conditions, but on the whole RLCs do not seem to be a successful safety measure.     

The use of videos in road safety training: Cognitive and emotional effects

The aim of the study was to evaluate the use of videos in educational programs for improving road safety. Particularly, we evaluated the cognitive and emotional effects of viewing videos taken from cameras placed along Italian highways and showing car crashes or traffic flow images.     

Drivers’ phone use at red traffic lights: A roadside observation study comparing calls and visual–manual interactions

Phone use while driving has become one of the priority issues in road safety, given that it may lead to decreased situation awareness and deteriorated driving performance. It has been suggested that drivers can regulate their exposure to secondary tasks and seek for compatibility of phone use and driving. Phone use strategies include the choice of driving situations with low demands and interruptions of the interaction when the context changes. Traffic light situations at urban intersections imply both a temptation to use the phone while waiting at the red traffic light and a potential threat due to the incompatibility of phone use and driving when the traffic light turns green. These two situations were targeted in a roadside observation study, with the aim to investigate the existence of a phone use strategy at the red traffic light and to test its effectiveness. N = 124 phone users and a corresponding control group of non-users were observed. Strategic phone use behaviour was detected for visual–manual interactions, which are more likely to be initiated at the red traffic light and tend to be stopped before the vehicle moves off, while calls are less likely to be limited to the red traffic light situation. As an indicator of impaired situation awareness, delayed start was associated to phone use and in particular to visual–manual interactions, whether phone use was interrupted before moving off or not. Traffic light situations do not seem to allow effective application of phone use strategies, although drivers attempt to do so for the most demanding phone use mode. The underlying factors of phone use need to be studied so as to reduce the temptation of phone use and facilitate exposure regulation strategies.     

Driver views on speed and enforcement

This paper reports on the results of a drivers’ survey regarding the effects of speed cameras for speed enforcement in Israel. The survey was part of a larger study that accompanied the introduction of digital speed cameras. Speed camera deployment started in 2011, and till the end of 2013 twenty-one cameras were deployed in interurban road sections. Yearly surveys were taken between 2010 and 2013 in 9 gas stations near speed camera installation sites in order to capture drivers’ opinions about speed and enforcement. Overall, 1993 drivers were interviewed.In terms of admitted speed behavior, 38% of the drivers in 2010, 21% in 2011, 13% in 2012 and 11% in 2013 reported that their driving speed was above the perceived posted speed limit. The proportion of drivers indicating some speed camera influence on driving decreased over the years. In addition, the majority of drivers (61%) predicted positive impact of speed cameras on safety. This result did not change significantly over the years. The main stated explanation for speed limit violations was time pressure, while the main stated explanation for respecting the posted speed was enforcement, rather than safety concerns.Linear regression and sigmoidal models were applied to describe the linkage between the reported driving speed (dependent) and the perceived posted speed (independent). The sigmoidal model fitted the data better, especially at high levels of the perceived posted speeds. That is, although the perceived posted speed increased, at some point the actual driving speed levels off (asymptote) and did not increase. Moreover, we found that the upper asymptote of the sigmoidal model decreased over the years: from 113.22 (SE = 18.84) km/h in 2010 to 88.92 (SE = 1.55) km/h in 2013. A wide variance in perceived speed limits suggest that drivers may not know what the speed limits really are.