MAJOR TRAFFIC VARIABLES Flashcards
(17 cards)
What are the 3 Major Traffic Variables?
A. Flow Rate or Volume
B. Speed
C. Density or Concentration
is defined as the number of vehicles passing a point during a specified period of time.
Flow Rate (q)
What is the formula used for Flow Rate?
q = N / t (veh/hr)
is defined as rate of motion in distance per unit time.
Speed (u)
Also called spot speed, _________ is simply the arithmetic mean of the speeds of vehicles passing a point within a given interval of time.
Time mean speed
is used to describe the rate of movement of a traffic stream within a given section of road. It is the speed based on the average travel time of vehicles in the stream within the section.
Space mean speed
It is also called the harmonic mean speed.
Space mean speed
is defined as the number of vehicles in a given length of road at an instant point in time.
Density (k)
What is the formula used for Density (k)?
k = n / L (veh/km)
What are some other Traffic Variables?
A. Time headway
B. Spacing
C. Time Occupancy
is defined as the time interval between passage of consecutive vehicles at a specified point on the road with a unit of time per vehicles.
Time headway (h)
What is the formula used for time headway?
h(sub)t = l / q
is the distance between two vehicles measure from the front bumper of a vehicle to that of another.
Spacing (s)
What is the formula used for Spacing (s)?
S = 1 / k
It can only be measure, however, if a detector is installed at a specific point on the carriage way. It is defined as the total time of a detector is occupied, divided by the total time of observation
Time occupancy (O)
Vehicles are not required to stop by any cause external to the traffic stream
Uninterrupted Flow
Vehicles are required to stop by any cause outside the traffic stream
Interrupted Flow
