Research On Capacity Influence Factors Of Basic Expressway Segment

With the speeding up of the urbanizing in our country, city scale constantly extends, and city layout occurs fundamentality change. Many metropolises in China invest substantive financing to build expressway. Urban expressway is to satisfy the transportation of largeness, long distance and speediness. It builds central reservation between opposed driving lane, the exit and entrance adopt whole control or partial control. Basic segment is not influenced by diverging, merging or weaving area nearby the ramp. Because the capacity of expressway is influenced by many factors, the traffic of many expressways is very crowd actually and not achieves the characteristic of speediness, big volume at all. So it is urgent to quicken the pace to study traffic characteristics and corresponding theory.This paper combines the research process of the country natural fund project; it introduces four advanced traffic flow detecting techniques of the data collection, investigation content of basic expressway segment, the choice of investigation place, time and concrete implementation of the data collection scheme. Then it uses a great deal of actual data to analyze traffic circulation characteristic of basic expressway segment in Beijing. It includes hour change characteristic of traffic volume, vehicles composition characteristic, vehicles direction distributed characteristic, lane distributed characteristic of traffic volume and velocity characteristic.According to complexity and variety of expressway capacity influence factors, it establishes hierarchy structure model of basic expressway segment influence factors by Analytic Hierarchy Process, analyzes influence factors of basic expressway segment, obtains relative weight of all indexes by calculating, and establishes appraisal index system of basic expressway segment capacity.It establishes factor set, evaluation set of basic expressway segment capacity, and makes corresponding result of fuzzy comprehensive evaluation by the principle of fuzzy comprehensive evaluation. Then it explains its concrete utilization as up-grade direction of Dongzhimen at second loop line of Beijing an example.Finally it analyzes the feasibility that using hydromechanics to analyze traffic flow by contrasting various characters between traffic flow and fluid flow. It analyzes influence of road alignment to basic expressway segment capacity by hydromechanics, and obtains viscous resistance and viscous movement differential equation when the vehicle drives on circular curve segment of expressway. And it infers that viscous resistance is correlated with sideway force coefficient, slope of crown and radius of circular curve. Radius of circular curve, sideway force coefficient and slope of crown are bigger, viscous resistance is smaller, the influence to capacity is smaller when the vehicle is running on nearside lane of circular curve; but radius of circular curve and sideway force coefficient are bigger, slope of crown is smaller, viscous resistance is smaller, the influence to capacity is smaller when the vehicle is running on fast lane of circular curve.