Study On Practical Methods Of Optimization For Integrating Timing And Spacing Resources In Signalized Intersections

As a critical technique of optimization design of signalized intersection (SI) and as the subject of this dissertation, the synthetic optimization is to achieve the optimal scheme integrating the timing and spacing resources. With the above subject as core, the dissertation, in view of study categories, can be divided into 5 parts as follows: design process, optimum design of space, phase and sequence design, optimum design of time, and integrated optimization of timing and spacing resources. Part 1 is the frame of the optimization procedure, and the following three parts are to work out initial scheme, while part 5 is to gain the optimal scheme through optimizing the initial scheme. The later four parts are the development of part 1 and are the focus; therefore all of them compose an interrelated and united method frame.What warrants should be used to judge the installation of traffic signals? What process does the optimum design of intersection judged installation of traffic signals comply with? Answers of the two problems are given in the 1st part of this dissertation. The optimal principal is put forward, which is the design scheme of SI should be optimal but not only meet the level of service (LOS). Thus precondition and orientation of this study are determined.Approach function split (AFS) is the main task of space design of SI. In the 2nd part of dissertation, more attention is paid to the following three issues: the installation of left-turn lane (LTL), the installation of right-turn lane (RTL), and the AFS.Treatments of left-turn (LT) are the most difficult problem of SI and are always troublesome for the traffic engineering. The following issues are discussed: warrants for LTL, the length of LTL, the installation of multi LTL, types of LTL configurations and design methods, the geometric design of LTL and other noticeable details. Warrants for LTL are studied using probability theory and the theory of queen, and obtained the LT volume of threshold for exclusive LTL. The study indicates that exclusive LTL should be installed in approaches generally in view of the traffic operation efficiency and safety. The length is a key design element of LTL. Firstly, the taper length and the deceleration distance are studied; secondly, the design methods of storage lengths for protected phase and unprotected phase are discussed separately, and storage lengths of varieties are summarized in charts. The criteria of multi LTL and special considerations are explored. Types of configurations and design are crucial for the safety and efficiency of LTL operation. So, some details are discussed as follows: types of LTL configurations, turn radius, guide lines, and signs and markings etc. It is suggested that LT should be shadowed and avoided trap lane, if possible. Varied installation methods are presented for different conditions.Treatments of right-turns (RT) in SI are also important for mixed traffic flow in China. Being similar to LTL, warrants, storage length and geometric design of RTL were studied. Warrants for RTL are analyzed in view of safety and traffic operation efficiency. According to the study of the HCM 2000, guidance figure for RTL installation is charted. In addition to meeting the requirements of deceleration and queuing, the length of RTL should also be sufficient for requirement of the stopping sight distance.Based on the studies of the former issues of LTL and RTL installations, the method for AFS is established according to two guiding principles: the matching of approach lanes and link lanes and the matching of approach lanes and exit lanes. So the approach function matrix is determined.