LOSS Evaluation for Continuous Downgrades Segments Based on Accident Frequency Prediction

2014 ◽  
Vol 505-506 ◽  
pp. 1061-1066
Author(s):  
Yi Xuan Sun ◽  
Chun Fu Shao ◽  
Meng Meng ◽  
Song Shou Ouyang
Keyword(s):  
Traffic Safety ◽  
Evaluation Method ◽  
Negative Binomial ◽  
Prediction Models ◽  
Safety Evaluation ◽  
Safety Performance ◽  
Accident Frequency ◽  
Sample Segment ◽  
Level 3 ◽  
Geometrical Factors

In order to evaluate traffic safety performance of continuous downgrades segment more accurately and quantitatively, a new safety evaluation method namely level of safety service (LOSS) is introduced. Based on the current traffic safety situation in China, the LOSS definition and classification method are studied systematically. In this paper, LOSS is built as a 5 levels framework and the graded threshold values are derived from accident frequency prediction models. The empirical research dataset includes 322 accidents data on a 15.27km continuous downgrades segment. The dataset is grouped into 16 fixed longitudinal grade sections to highlight the geometrical characteristics. Negative binomial model is best fitted among four candidate models, while the parameter estimation result indicates that geometrical factors, oversize vehicles mixed rate and average speed have significant positive effect on accident frequency. The overall LOSS of sample segment locates into the Level 3 interval, which means less safety performance than expected. As an extended application, LOSS specific to each fixed longitudinal grade section is analyzed.

scholarly journals In Search of the Consequence Severity of Traffic Conflict

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Ruoxi Jiang ◽  
Shunying Zhu ◽  
Pan Wang ◽  
QiuCheng Chen ◽  
He Zou ◽  
...  
Keyword(s):  
Traffic Safety ◽  
Evaluation Method ◽  
Prediction Models ◽  
Safety Evaluation ◽  
Threshold Value ◽  
Two Dimensions ◽  
Trajectory Data ◽  
Traffic Conflicts ◽  
Traffic Conflict ◽  
Accident Data

Currently, many studies on the severity of traffic conflicts only considered the possibility of potential collisions but ignored the consequences severity of potential collisions. Aiming toward this defect, this study establishes a potential collision (serious conflict) consequences severity model on the basis of vehicle collision theory. Regional vehicles trajectory data and historical traffic accident data were obtained. The field data were brought into the conflict consequences severity model to calculate the conflict severity rate of each section under different TTC thresholds. For comparison, the traditional conflict rate of each section under different TTC thresholds that considered only the number of conflicts was also calculated. Results showed that the relationship between conflict severity rate and influencing factors was somehow different. The conflict severity rate seemed to have a higher correlation with accident rate and accident severity rate than conflict rate did. The TTC threshold value also affected the correlation between conflicts and accidents, with high and low TTC threshold indicating a lower correlation. The results showed that conflict severity rate that considered each single conflict consequence severity was a little better than the traditional conflict rate that considered only the numbers of conflicts in reflecting real risks as a new conflict evaluation indicator. The severity of traffic conflicts should consider two dimensions: the possibility and consequence of potential collisions. Based on this, we propose a new traffic safety evaluation method that takes into account the severity of the consequences of the conflict. More data and prediction models are needed to conduct more realistic and complex research in the future to ensure reliability of this new method.

The Application of Traffic Conflict Technique as a Road Safety Evaluation Method: A Case Study of Hasselt Intersection

2016 ◽  
Vol 845 ◽  
pp. 394-403 ◽  
Author(s):  
Fardzanela Suwarto ◽  
Kami Hari Basuki
Keyword(s):  
Traffic Safety ◽  
Traffic Control ◽  
Evaluation Method ◽  
Prediction Models ◽  
Safety Evaluation ◽  
Road User ◽  
The Road ◽  
Traffic Conflict ◽  
Accident Data

The majority of traffic safety evaluations in the world generally have been conducted by colecting historical accident data. The data will then being analyzed using risk prediction models or before-after study that required an exact and reliable data. Meanwhile, the availability of accident data is rare where the rest actually consist of near-crashes and abnormal behaviour, which is mostly underreporting and lack of detail concerning the behavioural and situational of the event. Therefore, traffic conflict technique, is needed to assess traffic safety as another approach rather than waiting for several years until a number of accidents happen in a certain area. Hence the aim of this study is to make a safety evaluation towards a specific intersection in Hasselt Belgium using traffic conflict technique. The observation of conflict (near crashes) was carried out in intersection of Manteliusstraat – Dorpsstraat – Thonissenlaan in the Hasselt, Belgium. In order to differentiate slight conflict and serious conflict, the TA-value (Time of accident) was defined based on the estimated speed of the road user and estimated distance from the road user when conflict occurred. From the observation, it was found that the conflicts between car and pedestrian were the most frequent conflict, with 50% of the total conflict, and that the conflict between car with car and the conflict between car with cyclist were high in terms of severity level based on the TA-value. By taking these into consideration, it can be concluded that unsafe crossing for pedestrian and cyclist, different speed, and peak hour traffic were the causes of conflict. Therefore, it was concluded that traffic conflict technique can be used to assess and measure traffic safety in a certain road segment. Furthermore, in term of safety, the Manteliusstraat – Dorpsstraat – Thonissenlaan intersection should be modified with some alternatives; signalized intersection with toucan crossing and traffic control devices improvement

scholarly journals Safety Evaluation of Freeway Speed-Change Lanes Based on Crashes and Simulated Conflicts

2021 ◽  
Author(s):  
Lei Qin
Keyword(s):  
Traffic Control ◽  
Goodness Of Fit ◽  
Linear Models ◽  
Negative Binomial ◽  
Prediction Models ◽  
Control Strategies ◽  
Safety Evaluation ◽  
Safety Performance ◽  
Assessment Model ◽  
Crash Prediction Models

To facilitate the evaluation of the safety performance of freeway merge, diverge, and weave areas, conventional crash-based Safety Performance Functions (SPFs) were developed using generalized linear models (GLM) with a negative binomial (NB) error structure. However, crash-based SPFs may not take into account all factors that contribute to the crashes. The use of simulated conflicts as a surrogate safety measure to predict crashes can address this issue and provide recommendations for the designs and traffic control strategies. This approach was explored by using Surrogate Safety Assessment Model (SSAM) and VISSIM software to generate and analyze conflicts for merge areas on Ontario freeways. Crash-conflict integrated SPFs with different Time to Collision (TTC) thresholds were then developed and compared. Their predictive capabilities were also evaluated. To complement this analysis, the transferability of US crash prediction models to Ontario data was evaluated and the goodness-of-fit of these models was explored.

scholarly journals Safety Evaluation of Freeway Speed-Change Lanes Based on Crashes and Simulated Conflicts

2021 ◽  
Author(s):  
Lei Qin
Keyword(s):  
Traffic Control ◽  
Goodness Of Fit ◽  
Linear Models ◽  
Negative Binomial ◽  
Prediction Models ◽  
Control Strategies ◽  
Safety Evaluation ◽  
Safety Performance ◽  
Assessment Model ◽  
Crash Prediction Models

To facilitate the evaluation of the safety performance of freeway merge, diverge, and weave areas, conventional crash-based Safety Performance Functions (SPFs) were developed using generalized linear models (GLM) with a negative binomial (NB) error structure. However, crash-based SPFs may not take into account all factors that contribute to the crashes. The use of simulated conflicts as a surrogate safety measure to predict crashes can address this issue and provide recommendations for the designs and traffic control strategies. This approach was explored by using Surrogate Safety Assessment Model (SSAM) and VISSIM software to generate and analyze conflicts for merge areas on Ontario freeways. Crash-conflict integrated SPFs with different Time to Collision (TTC) thresholds were then developed and compared. Their predictive capabilities were also evaluated. To complement this analysis, the transferability of US crash prediction models to Ontario data was evaluated and the goodness-of-fit of these models was explored.

scholarly journals The variability of urban safety performance functions for different road elements: an Italian case study

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Paolo Intini ◽  
Nicola Berloco ◽  
Gabriele Cavalluzzi ◽  
Dominique Lord ◽  
Vittorio Ranieri ◽  
...  
Keyword(s):  
Negative Binomial ◽  
Prediction Models ◽  
Safety Performance ◽  
Common Trends ◽  
Main Research ◽  
Pavement Markings ◽  
Italian Case ◽  
Sight Distance ◽  
Safety Performance Functions ◽  
Urban Safety

Abstract Background Urban safety performance functions are used to predict crash frequencies, mostly based on Negative Binomial (NB) count models. They could be differentiated for considering homogeneous subsets of segments/intersections and different predictors. Materials and methods The main research questions concerned: a) finding the best possible subsets for segments and intersections for safety modelling, by discussing the related problems and inquiring into the variability of predictors within the subsets; b) comparing the modelling results with the existing literature to highlight common trends and/or main differences; c) assessing the importance of additional crash predictors, besides traditional variables. In the context of a National research project, traffic volumes, geometric, control and additional variables were collected for road segments and intersections in the City of Bari, Italy, with 1500 fatal+injury related crashes (2012–2016). Six NB models were developed for: one/two-way homogeneous segments, three/four-legged, signalized/unsignalized intersections. Results Crash predictors greatly vary within the different subsets considered. The effect of vertical signs on minor roads/driveways, critical sight distance, cycle crossings, pavement/markings maintenance was specifically discussed. Some common trends but also differences in both types and effect of crash predictors were found by comparing results with literature. Conclusion The disaggregation of urban crash prediction models by considering different subsets of segments and intersections helps in revealing the specific influence of some predictors. Local characteristics may influence the relationships between well-established crash predictors and crash frequencies. A significant part of the urban crash frequency variability remains unexplained, thus encouraging research on this topic.

Metro Operation Safety Evaluation

2014 ◽  
Vol 505-506 ◽  
pp. 467-470
Author(s):  
Li Yun Wei ◽  
Yong Bo Lv ◽  
Yuan Ren
Keyword(s):  
Traffic Safety ◽  
Safety Assessment ◽  
Evaluation Method ◽  
Comprehensive Evaluation ◽  
Weak Link ◽  
Management Strategies ◽  
Safety Evaluation ◽  
Fuzzy Comprehensive Evaluation ◽  
Comprehensive Evaluation Method ◽  
Urban Rail

In order to evaluate urban rail traffic safety performance comprehensively and to find the weak link to strengthen management, this article, it used the secondary fuzzy comprehensive evaluation method for safety assessment. the qualitative analysis was done to emphasis the structure importance and management strategies are put forward based on the results.

High-Grade Highway Safety Evaluation Method Based on Grey Clustering

2012 ◽  
Vol 594-597 ◽  
pp. 1412-1415
Author(s):  
Sheng Neng Hu
Keyword(s):  
Traffic Safety ◽  
Evaluation Method ◽  
Evaluation Model ◽  
Safety Evaluation ◽  
Highway Safety ◽  
High Grade ◽  
Highway Transportation ◽  
Grey Clustering ◽  
Safe Condition ◽  
Safety First

Evaluation for traffic safety is very important to improve traffic safety. First analyzes high grade highway security characteristic, then according to grey characteristics of traffic safety system, proposed high grade highway grey clustering evaluation model, and carries on the model to Henan province high grade highway's safe condition status evaluation, thus confirms this method the validity. The research showed that this model is a effective way which measure high grade highway transportation degree of security.

scholarly journals The Application Research on Safety performance Evaluation of Portal Crane based on Reliability Evaluation and risk Assessment

2021 ◽  
Vol 257 ◽  
pp. 01077
Author(s):  
Li Qin ◽  
Bin Zhang ◽  
Xinren Li ◽  
Zheng-qiu Huang
Keyword(s):  
Risk Assessment ◽  
Risk Management ◽  
Performance Evaluation ◽  
Evaluation Method ◽  
Safety Evaluation ◽  
Direct Application ◽  
Safety Performance ◽  
Application Research ◽  
Continuous Development ◽  
Portal Crane

With the continuous development of modern industry in our country, the use of cranes is becoming more and more common, but the unsafe incidents of cranes occur from time to time, which makes the risk assessment of cranes more and more important. Crane risk assessment has become an important part of crane risk management. In order to further promote the development of crane risk management, this paper tests the feasibility and effectiveness of this method through the study of fuzzy safety evaluation method and the direct application of this method to the risk assessment of portal crane.

scholarly journals Investigation of model calibration issues in the safety performance assessment of Ontario highways

2021 ◽  
Author(s):  
S.M. Morjina Ara Begum
Keyword(s):  
Negative Binomial ◽  
Prediction Models ◽  
Temporal Correlation ◽  
Negative Binomial Regression ◽  
Estimating Equation ◽  
Repeated Measurements ◽  
Safety Performance ◽  
Dispersion Parameter ◽  
Segment Length ◽  
Linear Modeling

A set of Safety Performance Function (SPFs) commonly known as accident prediction models, were developed for evaluating the safety of Highway segments under the jurisdiction of Ministry of Transportation, Ontario (MTO). A generalized linear modeling approach was used in which negative binomial regression models were delevoped separately for total accidents and for three severity types (Property Damage Only accidents, Fatal and Injury accidents) as a function of traffic volume AADT. The SPFs were calibrated from 100m homogenous segments as well as for variable length continuous segments that are homogeneous with respect to measured traffic and geometric characteristics. For the models calibrated for Rural 2-Lane Kings Highways, the variables that had significant effects on accident occurrence were the terrain, shoulder width and segment lenght. It was observed that the disperson parameter of the negative binomial districution is large for 100m segments and smaller for longer segments. Further investigation of the dispersion parameter for Rural 2-Lane Kings Highways showed that the models calibrated with a separate dispersion parameter for each site depending on the segment length performed better that the model calibrated considering fixed dispersion parameter for all sites. For Rural 2-Lane Kings Highways, a model was calibrated with trend considering each year as a separate observation. The GEE (Generalized Estimating Equation) procedure was use to develop these models since it incorporated the temporal correlation that exists in repeated measurements. Results showed that integration of time trend and temporal correlation in the model improves the model fit.

Safety Performance of One-Way Arterials

2020 ◽  
Vol 2674 (10) ◽  
pp. 548-559
Author(s):  
Srinivas R. Geedipally ◽  
Dominique Lord ◽  
Michael P. Pratt ◽  
Kay Fitzpatrick ◽  
Eun Sug Park
Keyword(s):  
Predictive Models ◽  
Traffic Control ◽  
Injury Severity ◽  
Negative Binomial ◽  
Prediction Models ◽  
Distribution Functions ◽  
Safety Performance ◽  
Safety Performance Function ◽  
Traffic Characteristics ◽  
Wide Range

Safety analysts are generally interested in understanding the differences in the safety performance when a two-way street is converted to a one-way operation or vice-versa. Literature exists to understand and predict the safety of two-way streets. However, safety prediction procedures are currently not available for assessing the safety performance of one-way arterials. This research was undertaken to develop safety prediction models for one-way arterials. To accomplish this objective, data collected in California, Illinois, Michigan, Oregon, and Texas were assembled that included a wide range of geometric design features, traffic control features, traffic characteristics, and crash records. The data were used to calibrate predictive models, each of which included a safety performance function (SPF) and several crash modification factors (CMFs). Separate SPFs were developed for fatal and injury crashes (i.e., fatal, incapacitating injury, non-incapacitating injury, and possible injury crash) and property-damage-only crashes. The SPFs were estimated using the negative binomial modeling structure. Severity distribution functions (SDFs) were also calibrated using the fatal and injury data. These functions can be used with the predictive models to estimate the expected crash frequency for each of four injury severity levels.

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