Basic HTML Version
72
Traffic Signal Systems Operations and Design: Isolated Intersections
While the models that we considered in the reading (Activity #8) provide an excellent framework
for understanding traffic flow at a signalized intersection, they lack an important ingredient that we
observe in the real world. The models are deterministic and the real world is stochastic. In this activity
we consider a very high resolution data set that was collected in Los Angeles that will allow us to
consider the messiness, or stochasticity, that is ever present in the real world.
In 2006, the Federal Highway Administration published the results of a study of traffic flow char-
acteristics along a four-block section of Lankershim Blvd. in Los Angeles. The study was based on
very high quality video that was taken from a 30-story building located adjacent to Lankershim Blvd.
Video image processing software extracted data on position, velocity, and acceleration for vehicles
traveling along the arterial for a 30 minute period at time intervals of 0.1 second. This is by far the
most detailed study of vehicle trajectories ever compiled.
Figure 46 shows an aerial view of one of the four signalized intersections included in this study. It
is the intersection of Lankershim Blvd., Campo de Cahuenga Way and Universal Hollywood Drive,
located near Universal Studios. Figure 47 shows the entire arterial. You took a video tour of this
arterial using the file a03.wmv (See Activity #3 in Chapter 1).
Figure 46.
Aerial view of Lankershim Blvd. intersection
Figure 47.
Lankershim Blvd. study area
You are given field data for one lane of a signalized intersection in the Excel spreadsheet. The data in
the “field data tab” give the location of eight vehicles over a period of three minutes at one foot resolu-
tion, and the time that each vehicle passes each one foot point. The data in the “arrival-departure data”
tab includes the arrival time at a given point and the departure time from a given point.
A
ctivity
10: U
sing
H
igh
R
esolution
F
ield
D
ata
to
V
isualize
T
raffic
F
low