Integrated traffic conflict model for estimating crash modification factors

Shahdah, Usama Elrawy; Saccomanno, Frank; Persaud, Bhagwant

doi:10.1016/j.aap.2014.05.019

Cited by 76 publications

(31 citation statements)

References 12 publications

(12 reference statements)

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“…The SSAM approach has seen increasing use in safety evaluations recently (, among others). However, several researchers raised two main concerns about using simulated conflicts in safety evaluation .…”

Section: Introductionmentioning

confidence: 99%

A comparison between PARAMICS and VISSIM in estimating automated field‐measured traffic conflicts at signalized intersections

Essa

Sayed

2016

J of Advced Transportation

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SUMMARYThe main objective of this study is to investigate the relationship between field-measured conflicts and simulated conflicts estimated from microsimulation model (PARAMICS) using the surrogate safety assessment model. An urban signalized intersection was selected for analysis. Automated video-based computer vision techniques were used to identify field conflicts. The applicability of a two-step model calibration procedure applied to VISSIM in a recent study was investigated using PARAMICS. In the first calibration step, the PARAMICS model was calibrated to ensure that the simulation gives reasonable results of average delay times. The second calibration step used a genetic algorithm procedure to calibrate PARAMICS parameters to enhance the correlation between simulated and field-measured conflicts. Finally, the results obtained from PARAMICS were compared with results obtained from VISSIM. The comparison included three aspects: (i) the car-following model and safety-related parameters; (ii) the correlation between simulated and field-measured conflicts; and (iii) the conflict spatial distributions. The results show that the default simulation model parameters give poor correlation with the field-measured data, and therefore, using simulation models without a proper calibration should be avoided. Overall, good correlation between field-measured and simulated conflicts was obtained after calibration for both models, especially at higher timeto-collision (TTC) values. At TTC threshold of 1.5 s, PARAMICS overestimates the number of conflicts and VISSIM underestimates it. Both models overestimated the number of conflicts at TTC threshold of 3.00 s. There were major differences between field-measured and simulated conflicts spatial distributions for both simulation models. This indicates that despite the good correlation obtained from the calibration process, both PARAMICS and VISSIM do not capture the actual conflict occurrence mechanism. Copyright

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Section: Introductionmentioning

confidence: 99%

A comparison between PARAMICS and VISSIM in estimating automated field‐measured traffic conflicts at signalized intersections

Essa

Sayed

2016

J of Advced Transportation

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“…Hence, there is a need to study the coexistence of Conventional Vehicles (CV) and AVs in the same road link at the same time, and to rethink the road infrastructure standards in a way that can suit both types of vehicles [8,9]. Traffic micro-simulation is a valuable approach to investigate how safety and operational traffic characteristics will change when AVs circulate in the streets, and to consider new Crash Modification Factors (CMFs) [10,11].…”

Section: Introductionmentioning

confidence: 99%

Introduction of Autonomous Vehicles: Roundabouts Design and Safety Performance Evaluation

et al. 2018

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Driving experiences provided by the introduction of new vehicle technologies are directly impacting the criteria for road network design. New criteria should be taken into consideration by designers, researchers and car owners in order to assure traffic safety in changed conditions that will appear with, for example, introduction of Autonomous Vehicles (AVs) in everyday traffic. In this paper, roundabout safety level is analysed on the originally developed microsimulation model in circumstances where different numbers of AVs vehicles are mixed with Conventional Vehicles (CVs). Field data about speed and traffic volumes from existing roundabouts in Croatia were used for development of the model. The simulations done with the Surrogate Safety Assessment Model (SSAM) give some relevant highlights on how the introduction of AVs could change both operational and safety parameters at roundabouts. To further explore the effects on safety of roundabouts with the introduction of different shares of AVs, hypothetical safety treatments could be tested to explore whether their effects may change, leading to the estimation of a new set of Crash Modification Factors.

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“…Although it could be greatly desirable and beneficial to conduct the safety analysis on the basis of traffic crash data, there are three critical issues associated with the existing crash database in China: (1) the crash data are heavily underreported, e.g., the property damage only data are typically not included and investigated by the police (Cheng, 2004;Fei et al, 2006); (2) the officially published crash counts are seriously biased due to the political concerns (Fei et al, 2006); and (3) the design layout of LWA at the signalized intersections is relatively new as opposed to the conventional intersections (and currently available only in the capital cities of China) and thus the number of crashes occurring at intersections as such is limited. Also, the historical research works (Gettman and Head, 2003;Oh et al, 2010;Autey et al, 2012;Shahdah et al, 2014) have indicated that the development of safety evaluation based upon the traffic conflict technique can well reflect the safety situation. Comparatively, traffic conflict data are easier to collect and measure as opposed to the crash events (due to the crash characteristics of randomness and rarity) at the intersections with LWA.…”

Section: Traffic-conflict Techniquementioning

confidence: 99%

Safety evaluation of signalized intersections with left-turn waiting area in China

Jiang

Zhang

Bai

et al. 2016

Accident Analysis & Prevention

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Integrated traffic conflict model for estimating crash modification factors

Cited by 76 publications

References 12 publications

A comparison between PARAMICS and VISSIM in estimating automated field‐measured traffic conflicts at signalized intersections

A comparison between PARAMICS and VISSIM in estimating automated field‐measured traffic conflicts at signalized intersections

Introduction of Autonomous Vehicles: Roundabouts Design and Safety Performance Evaluation

Safety evaluation of signalized intersections with left-turn waiting area in China

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