Research On Safety Evaluation Of The Highway Alignment Designing Based On Entropy

The effect of highway design on traffic safety has been paid close attention at present. decreasing hidden danger in road design, expanding the"safety space"of road, increasing the"tolerance"of road, reducing traffic accident have been become important research projects in the road safety. Research on safety evaluation index system and quantitative evaluation of relationship of indexes has important theoretic value and practical significance for scientific perfection of road design standard.In this thesis, the main effecting factors of road safety were analyzed, the main indexes effecting road design safety were chosen. According to the complexity system theory, the interrelation of safety factors in road design was studied. The levels model effecting factor of road design safety was established. The evaluation index system of safety factors in road design was composed. The safety complexity of highway design was analyzed by entropy theory. The complexity of information, function and structure was used as evaluation scales to establish an evaluation model. The influence degree of factors effecting road safety for highway design safety was analyzed quantitatively.In order to analyze the safety problem in highway design systematically, this thesis based on the study about interrelation and interaction of road safety factors and highway safety design, the safety complexity of highway design was analyzed, the evaluation model was established. According to the living example analyses, the safety degree of road design was evaluated; the complexity scales of information, function and structure were established. The relative parameters of system evaluation were found. The important index effecting safety degree of highway design was given.The thesis included seven chapters: introduction, analysis of influence factors and establishing model, establishment of evaluation index system, analysis of complexity, establishment of model and simulated analysis of mathematical model, analysis of living example and conclusion.In the first chapter, the present study situation of relative field at home and abroad was reviewed based on consulting literatures. The problems in the present relative studies were given, and the main content, research method, route of this thesis were explained. In the second chapter, the main factors and sub factors effecting highway design safety were defined from the interrelation and interaction of these factors. The evaluation method of road safety was analyzed systematically. It included time array method, relativistic accident rate method and so on, the merits and demerits of different evaluation methods. the highway design safety was evaluated by entropy theory of complex system to explore the safety degree, and lay a foundation for the correction of relative parameters in highway design, thereby.In the third chapter, the road design safety was analyzed and evaluated. In the safety evaluation index system, how to choose index is the key. Based on the safety evaluation index system of road design, the evaluation indexes were chosen, the levels model was established, the safety evaluation system of highway design was composed, the interaction of each level was analyzed. According to the complex relationship of factors, the interaction of each factor was analyzed.In the fourth chapter, the safety evaluation complexity of highway design was analyzed. It was suggested that there are information complexity, function complexity and structure complexity among the safety factors of highway design. The effecting model of different complexity on highway design was discussed.In the fifth chapter, the definition of entropy and relative theory were introduced. The three-dimensional vector space model was composed by complexity evaluation scale of entropy. A safety evaluation model of highway design was established based on the levels model. This chapter includes:(1) In the safety evaluation system of highway design, the interaction and influence of factors and sub factors affected the safety are random. In the thesis, the random variables were measured by"Entropy"for these random events. Entropy as a characteristic, which expresses undefined degree of exist state and motion state of a system, has been extensively used for the study on undefined nature and variety measurement in undefined phenomenon. It is the most appropriate scale to estimate undefined degree. So, the entropy theory was used for safety evaluation study of highway design in this thesis.(2) Based on the complexity measurement of entropy, an entropy function was defined to form a complexity vector space for different scale of each territory. The complexities of information, function and structure were used as evaluation scale; the interaction and relationship of safety evaluation factors in highway design were quantified. The analytical result of mathematical model has indicated that the influence of function complexity in safety evaluation of highway design is the biggest one.(3) A simplify of the function complexity in safety evaluation of highway design was given. It is advantageous to improve the safety degree of highway design.(4) Computer simulation is a main method to study complex system. In this chapter, the vehicle model was established using road design data and design standard. According to the road data, the analytical data during travel of vehicle is obtained by velocity and friction coefficient of wheel and ground. Based on the changeable range of parameters indexes, the safety hidden of road may be decided.In the sixth chapter, the safety evaluation of Huanggouling to Dongqing section in Mingyue to Dongqing highway of Jilin Province was established using mathematical model simulation. The evaluation result was compared with the traffic accident statistics which has made by traffic police of Jilin Province during last five years. The study result about safety evaluation system of road design based on entropy was tested and verified indirectly. That is the function complexity in evaluation indexes is more important for safety evaluation. The conclusion of this chapter is following:(1) In order to get high traffic properties, normally, some higher indexes are adopted under an allowable condition when a designer chooses value according to the standard of design. This design thinking will lead to a separation of practical vehicle velocity from indexes of highway line. In view of a single, the design is accordant with the demands of standard; however, in view of a whole, there is incoherence in it.(2) Normally, the maximum, minimum and general values of geometric elements are stipulated in the geometric design standard of highway. Because these values based on theoretical deduction, not on the safety study, it is difficult to quantify the relationship of geometric standard and safety. The seventh chapter is the summary of this thesis, which includes conclusion, point of bring forth new idea and research direction in future.