Safety Evaluation of Roundabouts in Georgia

Gbologah, Franklin E.; Guin, Angshuman; Rodgers, Michael O.

doi:10.1177/0361198119843265

Cited by 8 publications

(3 citation statements)

References 9 publications

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“…While early designs presented constraints, introducing innovative traffic rules has improved capacity and safety. Research findings highlight the significant advantages of roundabouts for intermediate traffic demands, while signalized intersections exhibit superior performance in high-traffic scenarios [ 17 , 18 ]. Roundabouts encourage low speeds, promoting safety, but possess unique crash profiles.…”

Section: Related Workmentioning

confidence: 99%

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Exploration of the application of Grey-Markov models in the causality analysis of traffic accidents in roundabouts

Li,

2023

PLoS ONE

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We propose a multivariate Grey-Markov model to quantify traffic accident risk from different causality factors in roundabouts that is uniquely suited for the scarce and stochastic traffic crash data from roundabouts. A data sample of traffic crashes occurring in roundabouts in the U.S. State of Michigan from 2016 to 2021 was collected to investigate the capabilities of this modeling methodology. The multivariate grey model (MGM(1,4)) was constructed using grey relational analysis to determine the best dimensions for model optimization. Then, the Markov chain is introduced to address the unfitness of stochastic, fluctuating data in the MGM(1,4) model. Finally, our proposed hybrid MGM(1,4)-Markov model is compared with other models and validated. This study highlights the superior predictive performance of our MGM(1,4)-Markov model in fore-casting roundabout traffic accidents under data-limited conditions, achieving a 3.02% accuracy rate, in contrast to the traditional GM(1,1) model at 8.30% and the MGM(1,4) model at 4.47%. Moreover, incorporating human, vehicle, and environmental risk factors into a multivariate crash system yields more accurate predictions than merely aggregating crash counts.

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Section: Related Workmentioning

confidence: 99%

“…Their implementation in the United States has led to decreased injury collisions and improved efficiency. However, the direct applicability of international research findings to the US context may be constrained due to various factors [ 18 ].…”

Section: Related Workmentioning

confidence: 99%

Exploration of the application of Grey-Markov models in the causality analysis of traffic accidents in roundabouts

Li,

2023

PLoS ONE

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“…However, the collision severity was reduced for both single and double-lane roundabouts. Another study by Gbologah et al [6] evaluated the safety performance of roundabouts in Georgia using the Empirical Bayes (EB) method. The results found 37% and 56% reduction in total and injury collisions, respectively.…”

Section: Introductionmentioning

confidence: 99%

Safety Impacts of Converting Stop-Controlled Intersections in Ottawa to Roundabouts

Abolhassani,

Hassan,

Kassim

2023

Proceedings of the 8th International Conference On Civil, Structural and Transportation Engineering (ICCSTE 2023)

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Roundabouts are becoming increasingly popular in North American road networks. They are used as a method for reducing traffic conflicts and enhancing road safety. This paper provides a statistical assessment of the impacts of roundabouts as modern safety treatment in the City of Ottawa. The assessment uses two statistical methods, which are Negative Binomial (NB) regression and Empirical Bayes (EB) before-and-after study to account for Regression to the Mean and time trend effects. The intersections within the City of Ottawa that were re-constructed as roundabouts within the period of 2012-2016 were taken as the study sample in this study. The results of the NB analysis showed significant Roundabout variable in total collisions, property damage only (PDO) collision severity and all collision impact type except for single motor vehicle (SMV) collisions. The results showed an increase in total, PDO, rear-end, and sideswipe collisions and decrease in angle collisions. The EB before-and-after study findings confirmed the increase in total, SMV, Sideswipe, rear-end and PDO collisions and the reduction of angle collisions, although the increase in SMV collisions was not statistically significant. The EB analysis also showed a 42% reduction in the number of injury+fatal collisions, which is very close to the estimated 48% reduction in angle collisions. In conclusion, this study shows an overall positive safety impact of roundabouts because of an approximately 42% reduction of the severe collisions that result in injury or fatality despite an increase of around 15% in the total number of collisions.

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Effectiveness of road safety interventions: An evidence and gap map

Goel,

Tiwari,

Varghese

et al. 2024

Campbell Systematic Reviews

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BackgroundRoad Traffic injuries (RTI) are among the top ten leading causes of death in the world resulting in 1.35 million deaths every year, about 93% of which occur in low‐ and middle‐income countries (LMICs). Despite several global resolutions to reduce traffic injuries, they have continued to grow in many countries. Many high‐income countries have successfully reduced RTI by using a public health approach and implementing evidence‐based interventions. As many LMICs develop their highway infrastructure, adopting a similar scientific approach towards road safety is crucial. The evidence also needs to be evaluated to assess external validity because measures that have worked in high‐income countries may not translate equally well to other contexts. An evidence gap map for RTI is the first step towards understanding what evidence is available, from where, and the key gaps in knowledge.ObjectivesThe objective of this evidence gap map (EGM) is to identify existing evidence from all effectiveness studies and systematic reviews related to road safety interventions. In addition, the EGM identifies gaps in evidence where new primary studies and systematic reviews could add value. This will help direct future research and discussions based on systematic evidence towards the approaches and interventions which are most effective in the road safety sector. This could enable the generation of evidence for informing policy at global, regional or national levels.Search MethodsThe EGM includes systematic reviews and impact evaluations assessing the effect of interventions for RTI reported in academic databases, organization websites, and grey literature sources. The studies were searched up to December 2019.Selection CriteriaThe interventions were divided into five broad categories: (a) human factors (e.g., enforcement or road user education), (b) road design, infrastructure and traffic control, (c) legal and institutional framework, (d) post‐crash pre‐hospital care, and (e) vehicle factors (except car design for occupant protection) and protective devices. Included studies reported two primary outcomes: fatal crashes and non‐fatal injury crashes; and four intermediate outcomes: change in use of seat belts, change in use of helmets, change in speed, and change in alcohol/drug use. Studies were excluded if they did not report injury or fatality as one of the outcomes.Data Collection and AnalysisThe EGM is presented in the form of a matrix with two primary dimensions: interventions (rows) and outcomes (columns). Additional dimensions are country income groups, region, quality level for systematic reviews, type of study design used (e.g., case‐control), type of road user studied (e.g., pedestrian, cyclists), age groups, and road type. The EGM is available online where the matrix of interventions and outcomes can be filtered by one or more dimensions. The webpage includes a bibliography of the selected studies and titles and abstracts available for preview. Quality appraisal for systematic reviews was conducted using a critical appraisal tool for systematic reviews, AMSTAR 2.Main ResultsThe EGM identified 1859 studies of which 322 were systematic reviews, 7 were protocol studies and 1530 were impact evaluations. Some studies included more than one intervention, outcome, study method, or study region. The studies were distributed among intervention categories as: human factors (n = 771), road design, infrastructure and traffic control (n = 661), legal and institutional framework (n = 424), post‐crash pre‐hospital care (n = 118) and vehicle factors and protective devices (n = 111). Fatal crashes as outcomes were reported in 1414 records and non‐fatal injury crashes in 1252 records. Among the four intermediate outcomes, speed was most commonly reported (n = 298) followed by alcohol (n = 206), use of seatbelts (n = 167), and use of helmets (n = 66). Ninety‐six percent of the studies were reported from high‐income countries (HIC), 4.5% from upper‐middle‐income countries, and only 1.4% from lower‐middle and low‐income countries. There were 25 systematic reviews of high quality, 4 of moderate quality, and 293 of low quality.Authors' ConclusionsThe EGM shows that the distribution of available road safety evidence is skewed across the world. A vast majority of the literature is from HICs. In contrast, only a small fraction of the literature reports on the many LMICs that are fast expanding their road infrastructure, experiencing rapid changes in traffic patterns, and witnessing growth in road injuries. This bias in literature explains why many interventions that are of high importance in the context of LMICs remain poorly studied. Besides, many interventions that have been tested only in HICs may not work equally effectively in LMICs. Another important finding was that a large majority of systematic reviews are of low quality. The scarcity of evidence on many important interventions and lack of good quality evidence‐synthesis have significant implications for future road safety research and practice in LMICs. The EGM presented here will help identify priority areas for researchers, while directing practitioners and policy makers towards proven interventions.

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Safety Evaluation of Roundabouts in Georgia

Cited by 8 publications

References 9 publications

Exploration of the application of Grey-Markov models in the causality analysis of traffic accidents in roundabouts

Exploration of the application of Grey-Markov models in the causality analysis of traffic accidents in roundabouts

Safety Impacts of Converting Stop-Controlled Intersections in Ottawa to Roundabouts

Effectiveness of road safety interventions: An evidence and gap map

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