Transportation Engineering Flashcards
Time Mean Speed Formula
TMS = ∑V / N
Space Mean Speed Formula
TMS = n / (∑1/ V)
Traffic Flow Formula
q = N/t
q= kv
Where:
q= number of vehicles
t= total time of observation
k= traffic density
Ability of a roadway to accommodate traffic volume
Traffic Capacity
The difference in position of vehicles arriving in a certain point
Space Headway
Space headway formula
Hs = 1 / k
The difference in time of vehicles arriving in a certain point
Time Headway
Time headway formula
Ht = 1 / q
The clear distance between 2 consecutive vehicles
Clearance
Time between two consecutive vehicles
gap
Speed Density Relationship Formula
V = Vf (1-k/kj)
Flow Density Relationship Formula
q = Vf/kj x k² + kVf
K optimum Formula
Kopt = kj / 2
Flow Speed Relationship Formula
q = kj/Vj x V² + Vkj
V opt Formula
V opt = Vf / 2
Max Flow Capacity Formula
q max = k opt / v opt
Traffic Max Capacity Formula
Vf Kj / 2
The standard system used to describe the queuing model
Kendall’s Notation
Traffic Intensity Formula
ρ = λ / μ
M|D|1: Average Length of queue
ǭ = ρ² / 2(1-ρ)
M|D|1: Average waiting time in queue
ω = ρ² / 2μ(1-ρ)
M|D|1: Average time spent in the system
t = 2-ρ / 2μ(1-ρ)
