Study Of Relationship Between Road Alignment And Accident Rate Along With Induction Factors On Freeway

Traffic accident is the unusual event induced by a single factor or multiple factorsof people, vehicles, road and environment. The road alignment as the basic elements ofroad, plays an essential role in the accident, especially the freeway, therefore, there wasa great significance to study the relationship between traffic accident and roadalignment conditions of freeway. This paper treated the freeway alignment as the mainline, to carry out the alignment safety, relationship between alignment and accident rate,accident induction research based on road alignment, as well as freeway traffic safetyenhancement research.Firstly, selected Jingzhu freeway Yuebei segment and Huning freeway Suchangsegment as the typical mountainous and plain freeway, collected their alignment andaccident data. The characteristics of horizontal, vertical and combined alignment wereanalyzed, and the segment was divided. The accident rate was calculated based on theroad segments, and the alignment safety was analyzed based on the road segment.Secondly, the relations of accident rate and horizontal indicators, vertical alignmentindicators, combination of horizontal alignment, combination of horizontal and verticalalignment were analyzed using the regression analysis. Then the models betweentangent length, horizontal curve radius, declination, vertical gradient, vertical curveradius and accident rate were developed. The relationships between combinationalignment and accident rate were analyzed. At last, the difference of the relationshipsbetween road alignment and accident rate were explored by comparative analysis.Although the relationship of the accident rate and alignment indicators canexplained the accident occurrence discipline, but traffic accidents are often not causedby only one alignment index, the study of the relationship between alignment indexand the accident rate cannot fully explain the accident occurrence discipline. So theprediction models of the mountainous and plain areas freeway were developed based onthe negative binomial distribution model. Quantitative indicators (elasticity coefficient)of accident induction factors were proposed based on the prediction model using theelastic analysis method. And then, the impact extent of accident induction factors andthe main induction factors of mountainous and plain areas freeway were determined..At last, the great vertical gradient and small horizontal curve radius segment ofmountainous freeway, small declination segment of plain freeway were selected as thetypical sections based on the study of relations between alignment and accident as longas induction factors. Then the safety measures were taken using the traffic engineeringtheory. These measures can be used to ensure the traffic safety of freeway.