On-Off Ramp Junction Capacity And Ramp Setting On Urban Expressway

Urban expressway is an importantcomponentof the roadnetwork system inlarge- and medium-sizedcities in China, and it's to be approved it's one of keymeasurements to release traffic congestion. However, urban expressway is a hugestructure with extensive investment, so the construction mustbe scientific andrational, which will guide to the city's developing direction. With rapid construction,the differentdemands are continually increasing. It's particularly urgentto do somerelevantresearchs onplanning, construction, operation and managementforurbanexpressway, because of the existing systemlagging farbehind thandemand.On- andoff-ramp junctions of urban expressway were chosen as two mainresearch objects depending on Research Fund forthe Doctoral Programof HigherEducation. On the basis of a large-scale traffic survey, statistical analysis theory,cellularautomaton theory, traffic wave theory and fuzzy control theory were used toanalyze and study the traffic flow operationcharacteristics, capacity computingmethods and ramp settings. Fromabove study, we hoped to find some scientic basison planning, construction, operation and managementforChinese urban expressway,as well as forotherhigh-speed roads orhighways.Combined detection methods were used to design traffic flow surveyprogramme with the modern magnetic imaging and metrocount impulse technologies.Aftersurvey application, representative urban expressway on- and off-ramp data fortraffic flow, roadway infrastructure, traffic management and control, and etc werecollected in China. Based on analyzing general ramp junctions'traffic flow operationcharacteristics, different characteristics for traffic volume and speed, headway,acceleration and deceleration, and density were studied according to collected data.Consequently, Weibull distribution model for headway and relationship models formacroscopic traffic flow parameters were set up. Those were a good foundation forestablishing on- andoff-rampjunctions computing models andrampsetting research.Highway Capacity Mannual of America was widely used to compute andanalyze capacity in China. Actually, there were some disadvantages someway. On-and off-ramp junctions computing methods were separately set up according to time gap acceptace theory, traffic wave theory, and automaton cellular theory. And then,the relevant parameters calibration forthose models was done according to collecteddata. So the possible capacity values were determined forChinese urban expresswayon- and off-ramp junctions. Finally, suggested possible capacity vaules for on- andoff-ramp junctions of Chinese urban expressway were put forward aftercomparisonanalysis on differentvalues.Further more, on-ramp control types and application effects were attentivelystudied depend on the computing capacity methods. Subsequently, three on-rampmetering strategies were concluded, such as mainroad priority strategy; alternatepassing through strategy, and signal control strategy. On this basis, on-ramp junctioncapacities were studied in condition of different control strategy after comparasinganalysis the advantages anddisadvantages.The new setting condtions forurban expressway ramp were put forward aimingat the uncertainty of present speed changing lanes setting conditions. On this basis,the length computing models for speed changing lanes were set up,collector-distributor lane and ramp distance setting methods were studied and therelevant suggested values ormethods were put forward separately. Combination themerits between fuzzy theory and neural network theory, a self-adaptive on-rampmetering method for urban expressway was put forward according to neuro-fuzzytheory, and also for the design programe for the controller and an example. Theexperiment results indicated that on-ramp junction capacity increased much more incondition of metering.Finally, the simulation models for on- and off-ramp junctions were built up inVISSIM software environment, the parameters calibration were done with collecteddata, and the simulation results were listed. At the same time, automaton cellulartraffic flow simulation modulars foron- and off-ramp junctions were developed withMATLAB toolboxes, and the simulation experiments were done with the differentlengths of speed changing lanes. The computing models and relevant ramp settingresearch findings were tested by the simulation results.