A full Bayes before-after study accounting for temporal and spatial effects: Evaluating the safety impact of new signal installations

Sacchi, Emanuele; Sayed, Tarek; El-Basyouny, Karim

doi:10.1016/j.aap.2016.05.015

Cited by 17 publications

(3 citation statements)

References 30 publications

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“…To account for the heterogeneity effects and time trends in before–after evaluation, Sacchi and Sayed developed a Koyck model which integrates both the heterogeneity effects and time trends into the model in a before–after analysis of the Signal Head Upgrade Program ( 35 ). Furthermore, Sacchi et al conducted a FB before–after study accounting for temporal and spatial effects to evaluate the safety impact of new signal installations ( 37 ).…”

Section: Literature Reviewmentioning

confidence: 99%

Before–After Evaluation of Left-Turn Lane Extension Considering Injury Severity and Collision Type

Guo

Sayed

2020

Transportation Research Record: Journal of the Transportation R

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Left-turn lanes are commonly used to provide space to accommodate vehicle deceleration and provide adequate storage of turning vehicles. The objective of this study is to evaluate the safety effectiveness of extending the length of left-turn lanes at signalized intersection approaches. Five years of collision data including injury severity and collision type from three treatment sites and 31 comparison sites in the City of Surrey, Canada were used in the study. The analysis focused on target crashes including left-turn-related rear-end and left-turn-related sideswipe collisions. A full Bayesian (FB) before–after analysis was conducted for all collisions, severity levels, and collision types. Multivariate Poisson–lognormal linear intervention models were used for the analysis. The treatment effectiveness index was calculated to quantitatively measure the effectiveness of the safety treatment. The FB before–after results showed that the treatment-related collisions were reduced by 57.4% following the implementation of extended left-turn lane. The reduction in injuries and fatalities collisions (63.8%) was greater than that in property damage only collisions (55.7%). The decrease in rear-end collisions (62.8%) was greater than that in sideswipe collisions (58.1%). The findings indicate a remarkable improvement in safety after the length extension of the left-turn lane.

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Section: Literature Reviewmentioning

confidence: 99%

Before–After Evaluation of Left-Turn Lane Extension Considering Injury Severity and Collision Type

Guo

Sayed

2020

Transportation Research Record: Journal of the Transportation R

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“…McGee et all ( 4–6 ) found that the effect of signalization at an intersection depends on the crash history at the intersection, the number of approaches (three- or four-leg), the signal timing, the operation speed and the total entering volume. Sacchi et al ( 7 ) employed a full Bayes before-after methodology to account for spatial and temporal characteristics when evaluating the safety effects of signalization. In another study, Srinivasan et al ( 8 ) demonstrated that the safety effects of signalization with and without left-turn lanes on two-lane roads would make a difference.…”

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confidence: 99%

Effects of Signalization at Rural Intersections Considering the Elderly Driving Population

Yue

Abdel-Aty

Lee

et al. 2019

Transportation Research Record: Journal of the Transportation R

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The main objective of this study is to quantify the safety impacts of signalization at Florida’s rural three-leg and four-leg stop-controlled intersections by estimating crash modification factors. The intersections are those in which stop signs are provided for the minor approaches or all-way stop-controlled intersections. The crash modification factors (CMF) are estimated using the cross-sectional method. Generalized linear models (GLM) and multivariate adaptive regression spline models (MARS) are employed with four years of Florida crash data. The K-nearest neighbor (KNN) and K-means clustering algorithms are implemented to identify the comparison sites which are sites having similar characteristics as those of the converted intersections. Furthermore, the quasi-induced exposure method is used to evaluate separately the safety effects of signalization for elderly and non-elderly drivers. According to the results, signalization contributes to an increase in property damage only (PDO) and rear-end crashes. In addition, elderly drivers are more at risk of being involved in such crashes than non-elderly drivers. In particular, at rural four-leg two-way stop-controlled intersections, signalization decreases crash severity, and a greater percentage of the decrease is observed for the elderly drivers than non-elderly especially when the intersection has a high level of major-road average annual daily traffic (AADT) and elderly driver proportion. This study also demonstrates that the MARS model shows a better model fit than the GLM model due to its strength in capturing nonlinear relationships and interaction effects among variables. This study’s findings have implications for both practitioners and researchers.

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“…They provide exact measures of uncertainty on the posterior distributions of these parameters. Sacchi et al (2016) used a full Bayes method to compare the effects of spatial and temporal dynamics in evaluating the effectiveness of road safety treatments. The analysed countermeasure was the installation of traffic signals at unsignalized urban or suburban intersections in British Columbia, Canada.…”

Section: Full Bayes Hierarchical Model With Spatial Effectsmentioning

confidence: 99%

Spatial Analysis of Traffic Accidents using GIS : the Case of Banda Aceh, Indonesia

Satria¹

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A full Bayes before-after study accounting for temporal and spatial effects: Evaluating the safety impact of new signal installations

Cited by 17 publications

References 30 publications

Before–After Evaluation of Left-Turn Lane Extension Considering Injury Severity and Collision Type

Before–After Evaluation of Left-Turn Lane Extension Considering Injury Severity and Collision Type

Effects of Signalization at Rural Intersections Considering the Elderly Driving Population

Spatial Analysis of Traffic Accidents using GIS : the Case of Banda Aceh, Indonesia

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