Subproblem 2a  Page 3 of 6 
ID# C102A03 
Subproblem 2a: Analysis of the Existing TWSC Intersection
Considering the Effects of the Adjacent Intersections
What additional data are needed when we consider the
effect of adjacent intersections? The additional data needed are for the
upstream signalized intersection. We need to consider the following
variables:

distance from the signalized intersection to the
subject TWSC intersection 

the progression speed of the through platoon 

the length of the traffic signal cycle 

the volume of the platooned or progressed vehicles 

the
saturation
flow rate of the signalized intersection 

the
arrival
type for major street through vehicles at the signalized intersection 
 the
effective
green time for the signalized intersection 
What is the potential effect of midblock driveways on
these arrival patterns? If there are midblock driveways between the
upstream signalized intersection and the subject TWSC intersection, vehicles
other than those in structured platoons from the signalized intersection
will arrive at the TWSC intersection. These vehicles may reduce the size of
the large gaps that otherwise would be present at the TWSC
intersection. While the HCM model does not account for this effect, you
should keep this in mind if the intersection you are studying has midblock
driveways.
What
computational tools are used to compute the capacity of a TWSC intersection
when considering the effect of adjacent intersections? We will use the
same procedure from Chapter 17 of the HCM for TWSC intersections. This time,
however, we will consider the upstream signal module that is included in
this procedure.
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