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Sub-problem 2b - Page 6 of 10

ID# C402B06

Sub-problem 2b: What are the Levels of Service in the Weaving Sections Located in the I-87/Alternate Route 7 Interchange?

Step 2. Results

The weaving analysis methodology of the HCM produces five distinct results:

  1. The estimate of space mean speed of weaving and non-weaving traffic in the weaving section.

  2. Determination of whether the flows are constrained or unconstrained by the weaving section geometry.

  3. Forecasts of average density based on the predicted speeds.

  4. Forecasts of level of service based on average density.

  5. Estimates of the capacity of the weaving section.

The results of the weaving analysis are provided in Exhibit 4-28.

After you've taken the time to review the data in Exhibit 4-28, consider the following questions:

bullet

How does the length of each weaving section affect its operation?

bullet

The volume ratio, VR, is more than twice as high in Weaves B and C as in Weave A; is this significant and if so, why?

bullet

What is the significance of the predicted speeds for the weaving and non-weaving traffic? The weaving speeds are approximately 16 to 18 mi/hr less than the non-weaving speeds for five of the time periods presented in the table; is this important and if so, why?

bullet

Why is the weaving traffic constrained? What is the practical implication of this finding?

bullet

What happens when the weaving flow rate exceeds the model limit?

bulletIn Weaves A and B, the volume ratio, VR, exceeds the model limit; what is the likely result that you would observe in the field?

Discussion:
Take a few minutes to consider these questions, and your answers to them. Proceed to the next page when you are ready.

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