Case Study 1 Problem 3 Styner/Lauder Intersection Moscow, Idaho

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Case Study 1Problem 3Styner/Lauder
IntersectionMoscow, Idaho
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Questions to be answered
Problem 3 Event Traffic Analysis - U.S. 95
Styner-Lauder Avenue Intersection

• Using the HCM, what would be the LOS at U.S.
  95/Styner-Lauder Avenue during a University of
  Idaho football game if the intersection were
  signalized?
• How would this LOS estimate change if a
  microscopic simulation model were used instead?
• What would the critical movement analysis
  technique tell us about the intersections
  sufficiency under these circumstances?

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Sub-problem 3a Oversaturated Intersection
Analysis

• What is the difference between volume and demand,
  and why is it important to distinguish between
  these two terms?
• Can the intersection operate at LOS F even when
  demand is less than capacity?
• What is the appropriate value of the
  duration-of-analysis parameter when demand
  exceeds capacity? When should multiple time
  periods be considered in a capacity and level of
  service analysis?

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Sub-problem 3a Oversaturated Intersection
Analysis

• How will the intersection perform, under both
  signal control and stop sign control, for these
  demand conditions?
• How should we proceed with this analysis?

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Step 2. Results
Sub-problem 3a Oversaturated Intersection
Analysis

• How will the intersection perform under signal
  control?

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Step 2. 1st period results signal control
Sub-problem 3a Oversaturated Intersection
Analysis
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Step 2. 2nd period results signal control
Sub-problem 3a Oversaturated Intersection
Analysis
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Step 2. 3rd period results signal control
Sub-problem 3a Oversaturated Intersection
Analysis
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Step 2. 3rd period results signal control
Sub-problem 3a Oversaturated Intersection
Analysis
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Microscopic simulation models
Sub-Problem 3b Using a Microscopic Simulation
Model

• HCM chapter 34 provides information on simulation
  models
• Microscopic simulation has several distinct
  attributes
• Individual vehicle interactions
• Detailed operation of traffic controllers
• Oversaturated conditions can be directly modeled
• Multiple period inputs
• Probabilistic nature of traffic flow and driver
  behavior
• More data are required
• Needs to be calibrated to local conditions

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Sub-Problem 3b Using a Microscopic Simulation
Model
Screen capture from a typical CORSIM animated
display
What insights can we draw from a comparison of
CORSIM and HCM results?
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Problem 3c Critical movement analysis

• What is critical movement analysis?
• What data are needed?
• What outputs are produced?
• Are the results any more or less valid than the
  results produced by the HCM or by microscopic
  simulation models?
• Why is there virtually no difference between
  estimated delay on the eastbound and westbound
  approaches to the intersection?
• What is the effect of grade and heavy vehicles?
• How do changes in vehicle mix affect the
  intersections when the intersection operates near
  or at capacity?
• What effects do heavy vehicles have on the
  intersection beyond changes to saturation flow
  rate?

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Problem 3c Critical movement analysis

• What is critical movement analysis?
• What data are needed to conduct critical movement
  analysis?

Data necessary to conduct a critical movement
analysis include - Approach volume - Number
of lanes - Lane configuration on each approach
Critical movement analysis is a method to
determine whether the projected volumes at a
signalized intersection will be under, near, or
over the intersection's capacity to accommodate
them.
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Problem 3c Critical movement analysis

• Are the results from critical movement analysis
  any more or less valid than the results produced
  by the HCM or by microscopic simulation models?
• Why is there virtually no difference between
  estimated delay on the eastbound and westbound
  approaches to the intersection?
• What is the effect of grade and heavy vehicles?
• How do changes in vehicle mix affect the
  intersections when the intersection operates near
  or at capacity?
• What effects do heavy vehicles have on the
  intersection beyond changes to saturation flow
  rate?

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Problem 3c Critical movement analysis

• What is the primary result of critical movement
  analysis?
• What are the limitations of critical movement
  analysis?

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Problem 3 Analysis

• The ability of a traffic signal to handle
  fluctuations is a function of the signal timing
  that is in the controller in the field. In time
  period 3 (430 - 445 pm) of our previous
  analysis, we changed the green ratio slightly to
  serve the traffic at the post-game traffic at the
  intersection.
• Would this green ratio be possible under the
  existing pre-timed control?

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Will the consideration of actuated traffic
controller settings affect our analysis?
Problem 3 Discussion

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End of Problem 3