Net speed calculator

Program Input: – Acceleration (a) & Deceleration rates (d) in ft/s2 – Distance traveled (L) in feet – Distance between intersections (D i ) in feet – Speed Limit (S lim ) in mph – Average waiting time at an intersection (T wait ) in seconds – Time step (h) in seconds (can be change in the program, but it isn’t ask to the user)

Output: – Net Speed (S net ) – Time-Distance-Speed Matrix – Time-Space Diagram

Run the program Set the Current Directory in the right folder (the one that contains MainProgram4 and the other functions) Open MainProgram4 Run MainProgram4

Matlab Command Window Time-Space Diagram Illustration of Inputs and Outputs

Time-Space Diagram Detail h=0.05 sec Instantaneous Speed and Distance traveled are recorded at each time step during non constant speed phases (acceleration end deceleration phases), otherwise (when the speed limit is reached, or when the vehicle is stopped), they are recorded only at the beginning and end of the phase)

Assumptions Constant Acceleration/Deceleration Intersections are equidistant Same waiting time at every intersection (uncoordinated intersections) No queuing space

Acceleration rateDeceleration rate AASHTO Green book 4 to 4.5 ft/s 2 (From 0 to mph) 11.2 ft/s 2 (comfortable) >=14.8 ft/s 2 (emergency) Traffic Engineering Handbook 3.6 ft/s ft/s 2 FHWA7.84 ft/s 2 (sedans) (0-60mph) ft/s 2 (sport cars) (0-60mph) Spurr6.4 ft/s 2 ( g; avg: 0.2g) Haas, Inman, Dixson, Warren 4.5 ft/s 2 (0.14g) (all speed)5.79 ft/s 2 (0.18g) (initial speed mph) Acceleration/Deceleration rates A lot of different values. But Deceleration rate always > Acceleration rate (cf. hypotheses)

Distance between intersection: Portland downtown: 1intersection every 260ft Phoenix downtown: 1intersection every 385ft Tucson: 440ft Los Angeles downtown N-S: 1intersection every 660ft (410ft E-W) Manhattan E-W: 1intersection every 880ft (255ft N-S) Lyon downtown (2è): 1intersection every 185ft *Distances calculated with Google Earth

Acc. rate6ft.sec-2 Dec. rate-6.5ft.sec-2 Speed limit25mph Distance traveled4000ft Distance between intersections260ft Average waiting time10sec S net = ft/s = 7.75 mph Reference situation: Time-Space Diagram

S net1 = 6.61 mph S net2 = 7.15 mph S net3 = 9.48 mph S net4 = 9.78 Time-Space Diagram for different situations

a 1, d 1, D i1, S lim2  S net = 6.63 mph ~ S net1 = 6.61 mph An increase in the Speed Limit (from 25mph to 45mph) doesn’t change the Net Speed much with D i1 (260), a 1 and d 1 (6 and -6.5 ft/s 2 ), because the maximum speed that can be reached is around 26.8 mph. ~26.8 mph Time-Space Diagram for different situations

Net Speed and Posted Speed Limit 34.1 mph 49.5 mph

Net Speed and Posted Speed Limit 26.8mph

Net Speed and D i

Net Speed and acceleration/deceleration rates

Net speed and waiting time

Limitations In practice: variable waiting time, coordinate intersections Non constant acceleration/deceleration: Acceleration vs speed for different gears schema Speed Acceleration 1 st gear 2 nd gear 3 rd gear 4 th gear 5 th gear