Before-and-After Empirical Bayes Evaluation of Automated Mobile Speed Enforcement on Urban Arterial Roads

Abstract

Speeding is a leading factor in road collisions and is found to contribute to approximately one-third of all fatal collisions. Speed enforcement is one of the most common countermeasures used to reduce speed. However, a gap exists in the literature regarding the effectiveness of automated mobile photo enforcement on urban arterial roads. This study addresses this gap using the before-and-after empirical Bayes method to account for regression to the mean effects and other confounding factors. Locally developed safety performance functions and yearly calibration factors for different collision severities were obtained by using a reference group of urban arterial roads. The evaluation period covers 8 years. Collision records, deployment information, traffic counts, and road geometric data were collected. The results showed consistent reductions in different collision severities; the reductions ranged from 14% to 20%, with the highest reductions observed for severe collisions. The enforced segments were further categorized according to site selection criteria and deployment hours to examine the effect of enforcement on collision reduction. More reductions were found at segments that had more collisions during the before period and longer deployment hours. The study also compared the safety effects of continuous and discontinuous enforcement strategies on different arterials, and the analysis revealed that continuous enforcement achieved more reductions across all severities and types of collisions. The study also investigated the spillover effects on adjacent unenforced approaches. Significant reductions were found, and these results are discussed with regard to the general and specific deterrence of the enforcement.

Before-and-After Empirical Bayes Evaluation of Achieving Bare Pavement using Anti-Icing on Urban Roads

“…The study adopted a conventional analysis approach, which has been known to lead to biased conclusions owing to the method’s inability to account for RTM effects and other confounding factors. The before-and-after EB approach used in this study can address all of the major limitations that are associated with the use of conventional safety analysis techniques ( 29 , 30 ). In addition, the monetary value of the expected change in frequency of collisions is estimated, which may help in assessing the economic feasibility of anti-icing WRM and provide WRM agencies with useful information about the economic performance of achieving BP using anti-icing.…”

Assessing the Effectiveness of an Integrated Speed Management Plan on Highways

“…It was also found that there was a time-halo effect of at least two days after the police vehicles had left. Furthermore, several studies found speed enforcement to be not only effective but also offer considerable safety improvements (Gouda & El-Basyouny 2017;Li et al 2015;Elliott & Broughton 2005;Wrapson et al 2006;Walter & Broughton 2011;Cruzado & Donnel 2009). In a review that was conducted by Elliott & Broughton (2005), it was shown that a reduction of 4.8 km/h in the mean speed was achieved by using stationary and visible enforcement.…”

“…This could be achieved through improving the design and safety of road facilities as well as launching integrated initiatives that aim to modifying drivers' behavior and prevent collisions (Shalkamy et al 2018;Shalkamy & El-Basyouny 2020) Many factors contribute to road collisions such as limited sight distance, inclement weather, driver fatigue, and, most importantly, speeding-which was estimated to be the main contributing factor for 30% of fatal collisions (Shalkamy et al 2020;Richards et al 1985). It is generally accepted that speeding is a causal factor in collision occurrence with significant implications to the likely outcome of a road collision (Li et al 2015). Speed could be related to safety in two different ways.…”

“…Education measures include creating media campaigns to increase public awareness about the dangers of speeding. Speed enforcement aims to modify the behavior of drivers by first detecting and then ticketing violators who drive over the posted speed limits (Li et al 2015). However, it may be argued that the most relied-upon approach to improving driver's compliance with speed limits is traffic-law enforcement initiatives (Bates et al 2012).…”

“…They are typically achieved through establishing traffic laws, policing these legislations, and applying penalties to offenders and violators (Watson et al 1996). The use of coordinated manned traffic enforcement operations has been found to have significant improvements on road safety (Li et al 2015). Deterrence by way of manned enforcement is instantaneous, as police officers usually issue speeding tickets on the spot (Bates et al 2012).…”