年平均日交通量.ppt
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1、Chapter 3. Volume, Density & Speed Studies and Characteristics,Volume (rate of flow) - intensity of traffic movement Speed - motion condition Density - distribution of traffic flow over space Relationship among three parameters - mathematical equations,1. Volume,Volume - is defined as the number of
2、vehicles that pass a point on a highway, or a given lane or direction of a highway, during a specified time interval, generally a day or an hour.,Some useful volumes,AADT (Average Annual Daily Traffic 年平均日交通量) AAWT (Average Annual Weekday Traffic 年平均工作日交通量) ADT (Average Daily Traffic 平均日交通量) AWT (Av
3、erage Weekday Traffic 平均工作日交通量),These four volumes remain at macroscopic level,Daily variation factor (DF) - is defined as ratio of AADT over yearly average volume for particular day of week (Monday, Tuesday etc.),Calibration of Daily Variation Factors,Monthly variation factor (MF) - is defined as r
4、atio of AADT over ADT for particular month of the year,Calibration of Monthly Variation Factors,Hourly volumes and peak hour volume (小时流量,高峰小时流量) Hourly volumes are used to reflect variation (fluctuation) of traffic volume in a day Peak hour volume is defined as the volume in the single hour that ha
5、s the highest hourly volume,Rate of flow (流率)- defined as an equivalent hourly volume for a given interval (interval can be 5, 10, 15 minutes) used in design to reflect the worst scenario used in modeling mathematical relationship among parameters in research generally the shorter the interval the h
6、igher the rate of flow,Interval Volume Interval Volume 7:00 7:05 15 7:30 7:35 17 7:05 7:10 25 7:35 7:40 35 7:10 7:15 18 7:40 7:45 28 7:15 7:20 42 7:45 7:50 32 7:20 7:25 31 7:50 7:55 26 7:25 7:30 18 7:55 8:00 20,V5 = (180, 300, 216, 504, 372, 216, 204, 420, 336, 384, 312, 240) V10=(240, 360, 294, 312
7、, 360, 276) V15=(232, 364, 320, 312),Max V5 = 504; Max V10 = 360; Max V15 = 364 Hourly volume = 307,Peak hour factor (高峰小时系数)- is defined as the ratio of hourly volume divided by maximum rate of flow,PHF is used to reflect the fluctuation of volume distribution in an hour!,PHF5 = 307/504 = 0.61; PHF
8、10 = 307/360 = 0.85; PHF15 = 307/364 = 0.84;,Peak-Hour-Factor (PHF),The 30th hourly volume (第30位小时交通量) - defined as an hourly volume at which its ranking on yearly-counting curve counts 30th among 8760 hourly volumes in a year DDHV (Directional Design Hourly Volume 设计小时流量) - DDHV = AADTK D where: K
9、is proportion of daily traffic occurring during the peak hour, expressed as a decimal; D is proportion of peak-hour traffic traveling in the peak direction, expressed as a decimal,D= ratio of design hour volume in the major direction to the total (方向性系数),K=ratio of design hour volume to the 24 hour
10、volume (设计小时系数),Relationship Between DDHV and AADT,In general D and K is constant!,VMT (Vehicle Miles Traveled=车英里) or VKT(Vehicle Kilometers Traveled 车公里) - defined as a product of number of vehicles and miles (or kilometer) traveled by these vehicles,Estimation of Vehicle-Miles Traveled on a Limit
11、ed Network: An Example,PCE and PCU (小汽车当量)- defined as the number of passenger cars displaced by one truck, bus, or RV in a given traffic stream Traffic intensity can be used as criterion to determine passenger car equivalent,2. Speed,Time mean speed (TMS,时间平均车速) - defined as the average speed of al
12、l vehicles passing a point on a highway over some specified time period Space mean speed (SMS,空间平均车速) - defined as the average speed of all vehicles occupying a given section of a highway over some specified time period,TMS is a point measure, while SMS is a measure relating to a length of highway o
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