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Two-Way Stop Control Potential Capacity with Upstream Signal

Jeanne Bowie
Kinney Engineering
Two-Way Stop Control Potential Capacity with Upstream Signal was posted on May 14th, 2012 at 6:27 PM EDT
regarding Chapter 19: Two-Way Stop-Controlled Intersections

I have a question about how to apply equations 19-33, 19-34, and 19-35. Under equation 19-33, if the total conflicting flow for a movement is less than the platooned flow rate, the unblocked conflicting flow rate is set to zero. In equation 19-35, if the unblocked conflicting flow rate is zero, then the denominator is zero and the equation cannot be used. In this situation, what should be used as the potential capacity? Do you just use the potential capacity if there are no upstream signals (equation 19-32), or is the conflicting flow during the unblocked period actually supposed to be set to a value other than zero?

Erik Ruehr
VRPA Technologies
RE: Two-Way Stop Control Potential Capacity with Upstream Signal was posted on May 28th, 2012 at 9:12 PM EDT

Based on my reading of Equation 19-35, if the unblocked conflicting flow rate is zero, the potential capacity will also be zero. I don't see a way that the denominator of Equation 19-35 could ever be equal to zero. In the case of any problems with the upstream signal calculation, an approximate answer can be determined by igoring the upstream signals portion of the procedure and obtaining an answer assuming there are no adjacent signals.

Jeanne Bowie
Kinney Engineering
RE: Two-Way Stop Control Potential Capacity with Upstream Signal was posted on July 13th, 2012 at 5:30 PM EDT

For equation 19-33, I ended up assuming that the value of conflicting flow during the unblocked period was very small (0.1, for instance) under the "otherwise" condition and was able to complete my analysis.

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