Traffic Engineering - Analysis

Transcription

1 Traffic Engineering - Lecture 4: Shocwave nalysis, PhD ssistant Professor Public Wors Dept. Faculty of Engineering airo University 1 ourse Syllabus Traffic System Users Vehicles Traffic Networ WHT? WHY? HOW? Data ollection Traffic Surveillance Information/communi cation technologies Decisions Info System Evaluation Data nalysis (studies) ctual Performance Measures ontrol Options Evaluation Traffic Simulations Expected Performance Measures Evaluation Schema Models System ontrol Geometry ontrols Operations Integration Demand / land-use 2 1

2 Shocwaves What? acup or ueuing as a results of a sudden decrease in roadway capacity (reduction in number of lanes, red traffic signal, accidents., slow moving truc etc). 3 Shocwaves TYPES 1) acward Propagating 2) Forward Propagating time 3) Stationary 4 2

3 Space- Diagrams ssuming that all vehicles are travelling with a constant speed, the space-time diagram will loo lie this Slope= vehicle speed 5 Space-time Diagram at signalized intersections asic oncepts: Space-time Slopes: represent speeds Traffic State: an area with steady-state vehicle speeds (consistent space-time slopes) Shocwave speed (): is the slope of the boundary between two traffic states Red signal stop Forming shocwave Red signal timing clearing shocwave 6 3

4 asic oncepts: State : Free-Flow State State : Vehicles Stopping State (red signal) State : Vehicles flow at full section capacity Red signal learing shocwave ( ) Forming shocwave ( ) Red signal phase length 7 asic oncepts: State : Free-Flow State State : Vehicles Stopping State (red signal) State : Vehicles flow at full section capacity to results in a Forming shocwave to results in a learing shocwave 8 4

5 Estimation of Shocwave Speed +ve value for forward propagating shocwave -ve value for bacward propagating shocwave apacity to results in a Forming shocwave to results in a learing shocwave 9 Estimation of haracteristics Red signal ( ) ( ) Red signal timing clearing Max ueue length Reach Total 10 5

6 Example: Signalized intersection Vehicles are flowing with a rate of 1000 veh/hr pproached a red signal (with 60 sec red phase) Estimate the speed of the forming/ clearing shocwaves. Estimated the max ueue length Estimated the distance the ueue will reach onsider the model u= Example: Signalized intersection State : = 1000 veh/hr or14.64veh / m 2 80 (80) 4(0.8)(1000) 2(0.8) 12 6

7 Example: Signalized intersection State : = 0 = j = 80/0.8=100veh/m State : = max =80*100/4=2000 veh/hr = j /2= 100/2=50veh/m 13 Example: Signalized intersection m m Red signal ( ) ( ) 14 7

8 Example: Signalized intersection 11.69m 40m Max 11.69* m Q Q Q reach Q Q Q m reach reach max reach reach 60 sec(0.0167hr) clearing Total Max ueue length Reach 15 Space-time Diagram along a highway with a slow moving truc asic oncepts: State : Free-Flow State State : Vehicles slowing down behind a slow truc State : Vehicles flow with full section capacity Truc speed (u t ) Truc enters Truc exits Forming shocwave ( ) learing shocwave ( ) 16 8

9 Shocwaves along a highway with a slow moving truc Estimation of Shocwave Speed +ve value for forward propagating shocwave -ve value for bacward propagating shocwave apacity to results in a Forming shocwave to results in a learing shocwave 17 Shocwave along a highway with a slow moving truc Estimation of haracteristics Truc on-road (u t ) Max ueue length ( ) ( ) clearing Reach Total 18 9

10 Shocwaves along a highway with a slow moving truc Example: slow moving truc Vehicles are flowing with a rate of 1000 veh/hr slow moving truc (with 20 m/hr) entered the highway and exists after 500 m. Estimate the speed of the forming/ clearing shocwaves. Estimated the max ueue length. Estimated the distance the ueue will reach onsider the model u= Shocwaves along a highway with a slow moving truc Example: slow moving truc State : = 1000veh/hr or14.64veh / m 2 80 (80) 4(0.8)(1000) 2(0.8) 20 10

11 Shocwaves along a highway with a slow moving truc Example: slow moving truc State : u = 20 m/hr = (80-20)/0.8=75 veh/m = 75(20)=1500 veh/m State : = max =80*100/4=2000 veh/hr = j /2= 100/2=50veh/m 21 Shocwaves along a highway with a slow moving truc Example: slow moving truc m m Note the sign 22 11

12 Shocwaves along a highway with a slow moving truc Example: slow moving truc -Truc-on-road 8.28m 20m Max ueue length Truc on road 0.5 / hr Q reach 0.5m Max * m Total Reach 23 12