Study On The Technical Indicators And Adaptability Of Freeway Diamond Interchange’s Critical Area

This paper are based on the technical indexes and traffic adaptability of freeway diamond interchange, adopting the method of mathematical statistics and its theory, system analysis and simulation technology for the further research on―bottleneck‖ of freeway diamond interchange in our countrywith the field measurement and field experimental data. Including speed-change lane of freeway diamond interchange, traffic operation characteristics of intersection, traffic adaptability of intersection in freeway diamond interchange without signal intersection, traffic adaptability of toll station in freeway diamond interchange, the theory of selecting the form of diamond interchange, the way to determine the length of speed-change lane in non-signaled intersections of diamond interchange and mark setting requirements considering the problem that mark cannot be obscured,etc.Through indoor and outexperiments, drivers’ physiological and psychological characteristics, including the data of pupil diameter approximate entropy parameter in eye tracking test are obtained, by analyzing driver’s perceptive, psychological and visual traffic characteristics on the deceleration ramp of diamond interchange and using experimental method based on the performance theory of driver’s physiology and psychology, drivers’ characteristics including parameters of driver’s physiology and psychology, and approximate entropy of pupil diameter in consciousness and visual senseare obtained;This paper focuses on analyzing traffic accident mechanism model and its application of the intersection in diamond interchange with objective and subjective reasons. In addition, putting forward the relationship between accidentmechanism and accident type of the intersection in diamond interchange. Using Logistic regression method to build an acceptable fault-gap model for left turn in the intersectionand analyze the driving mechanism that the conflicts caused by the acceptable gap.To start with conflicts in non-signaled intersections of diamond interchange, by analyzing the priority in conflict zones, the theoretical method for calculating traffic capacity of a single conflict group and multiple conflicts in the condition of saturated and unsaturated is obtained. Utilizing the theory of intermittent reception and traffic conflicttechnique to calibrate parameters in the model, and adopting VISSIM simulation techniques to calibrate the adaptable traffic volume in non-signaled intersections of conflict zones, and finally concluded that the traffic adaptability is 328 pcu/h, when the large vehicles entering rate is 10%. By to establish traffic volume models of Toll stations.It is concluded that the simulation results of traffic adaptability composed by different proportion of vehicle are consistent with the theoretical calculation under the mixture condition of MTC and ETC, by analyzing the traffic performance and service time in the tollbooth of diamond interchange, calibrating model parameters with VISSIM simulation techniques and changing the number of ETC channel and the percentages of ETC users in traffic flow and the composition of the vehicle.In the basis of the principle of selecting the type of diamond interchange, analyzing classifications and selecting factors of diamond interchange. The factors are analyzed by multiple attribute decision making theory. In the paper we decompose the influence factors that restricting the selection of diamond interchange, and determine the weight of various restricting factors by using multiple attribute decision making theory, and establish quantitative calculation model to select the type of diamond interchange based on the theory of multiple attribute decision making. With ShiYang interchange on the freeway-ring around Nanjing as an example, adopting multiple attribute decision making theory to analyze the diamond interchange scheme and the pros and cons of all kinds of feasible solutions. when it comes to adopt reconstruction plan for the built diamond interchange, the management measures should be first improved, and the civil engineering measures should be followed by; For new diamond interchange, multiple attribute decision making theoryshould be applied to analyze the effect of various factors combining with the forward adaptivetrafficvolume duringthe planning and designing phase to determine the best diamond interchange type selection scheme.In the point of conflicts in non-signaled intersections of diamond interchange, putting forward the theory of conflict critical gap. By assuming condition of non-signaled diamond interchange, establishing the model of conflict delay and dividing delays caused by conflicts into queuing delay, waiting delay, accelerating delay and decelerating delay. In addition, this paper analyzesthe delay time caused by conflict under the condition when the traffic volume is 330pcu/h mixed with various large, medium and small vehicles. And calculate the running speed of 51.5km/h deceleration ramp minimum length is 263m;For visual range in the intersection of diamond interchange across non-signaled bridge mainlines and the problem that large vehicles obscure marks, a calculation model based on the probabilityare set up to determine the visual range that large vehicles obscuring the marks. In addition, this paper makes an assumption of the model to calculate the probability of large vehiclesarea little bit in front of little ones and obscure them in the area of sign identification in different lanes,andrecognitionvisual range. Through analyzing the example to calculate the recognition visual range in non-signaled intersections of diamond interchange and the probability of large vehicles are obscured. In the section of a freeway which probability is higher, it is necessary to set marks repeatedly to lower the probability that traffic sign information is obscured. At the same time, flexible settings of signs should be cooperated to improvetraffic information acquisition for drivers.