交通流理论chap2.pdfVIP

TRAFFIC STREAM CHARACTERISTICS BY FRED L. HALL4 4 Professor, McMaster University, Department of Civil Engineering and Department of Geography, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7. CHAPTER 2 - Frequently used Symbols k density of a traffic stream in a specified length of road L length of vehicles of uniform length ck constant of proportionality between occupancy and density, under certain simplifying assumptions ki the (average) density of vehicles in substream I qi the average rate of flow of vehicles in substream I Å average speed of a set of vehicles A A(x,t) the cumulative vehicle arrival function over space and time k jam density, i.e. the density when traffic is so heavy that j it is at a complete standstill u free-flow speed, i.e. the speed when there are no f constraints placed on a driver by other vehicles on the road 2. TRAFFIC STREAM CHARACTERISTICS This chapter describes the various models that have been developments in measurement procedures. That section is developed to describe the relationships among traffic stream followed by one providing detailed descriptions and definitions characteristics. Most of the work dealing with these relationships of the variables of interest. Some of the relationships between has been concerned with uninterrupted traffic flow, primarily on the variables are simply a matter of definition. An example is the freeways or expressways. Consequently, this chapter will cover relationship between density of vehicles on the road, in vehicles traffic stream characteristics for uninterrupted flow. In per unit distance, and spac