The Study of Signal Intersections in Risk Analysis and Safety Assessment Models
Date Issued
2012
Date
2012
Author(s)
Lin, Szu-Min
Abstract
The conclusion of the analysis related to the traffic safety in the past may mostly come with hidden differences contributed by individual accidents. It is neither easy to present a concrete way for improvement. nor to find the correlation between the accidents and the traffic facilities. In order to make the accident factors as concrete as possible in this research, the intersections are categorized into 18 types of blocks that include entry, pass, and exit according to the characteristics and directions of the traffic flow. Through the statistical analysis of the accidents, this study divides the accidents of high frequency into four accidental categories, including adjacent passing, reverse passing, parallel left-turn, and parallel right-turn. To explore and establish the arguments for the study, factors of intersections, environment, traffic controls, and traffic characters have been taken into consideration, therefore the investigation of the relation between the accident risk of intersections and these factors helped build the model of signal intersections in risk assessment and safety assessment models. Besides, this study also investigate the accident patterns with conditions that motorcycles with and without direct left turns at intersections, and then speculation on the advantage of reducing the intersection risk by the analyzed data was conducted.
According to the conclusion of the analysis, the risk model of adjacent passing makes the average driving speed measurable, including the lane continuity, the lane design, the clearance time; the risk model of reverse passing measures the straight speed, the light configuration, the traffic signal type, the left-turn space of car standby, the related signal configuration, and the lane design; the risk model of parallel left-turn is concluded to be abke to measure the light configuration, the turning radius, the asymptote lane type, the lane for a left-turn purpose, the left-turn space of car standby, and the lane continuity; the risk model of parallel right-turn can measure the average driving speed, the jug handle installation, and the turning radius. With the discussion above being complete, ways of improvements are presentable based on the finalized analysis and the observation of data. For example, the accident of adjacent and reverse passing can be reduced by modifying the position of the signal, reviewing the design of progression signal, or reestimating whether the clearance time is enough. Moreover, the limit of turning based on the difference of lane design must have clear signals or limits to lower the accident risk.
Through the model of the accident risk analysis and the safety assessment, not only can it predict and assess the accident risk of the intersections, but also assess the safety of improving the intersections. Besides, the threshold values of the high frequent accident were determined according to the conclusion of accident risk assessment in the intersections, the values are references for prioritized improvement approaches.
Subjects
Safty Intersection
Accident Analysis
Risk
Quantification Theory Type I
Improving the Traffic Engineering
Multivariate Analysis
Type
thesis
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