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Work Zone Capacity

Kevin Murai
State of California Department of Transportation
Work Zone Capacity was posted on January 9th, 2019 at 5:04 PM EST
regarding Chapter 10: Freeway Facilities Core Methodology

Equation 10-9 Work zone capacity As noted, the average queue discharge drop rate is higher in a freeway work zone than in a non-work zone. By using these rates in equation 10-9, the calculated work zone capacity will always be greater than the non-work zone capacity, which should not be the case. Should the denominator in equation 10-9 be adding rather than subtracting the average queue discharge drop rate? For example

QDRwz=2000 Cwz (13.4% avg queue discharge drop) = 2309 Cnon-wz (7% avg queue discharge drop) = 2151

If you revise equation 10-9 by adding the avg queue discharge drop rather than subtracting, then Cwz = 1764 Cnon-wz = 1869 These rates make more sense. Any clarification would be appreciated. Thank you.

(Edited July 9th, 2020 at 1:31 PM EDT)
Cooper Calhoun
Alabama Department of Transportation
RE: Work Zone Capacity was posted on January 24th, 2020 at 3:12 PM EST

I am noticing the same situation with the equation for work zone free-flow speed. As stated on pg.10-44 the higher the work zone speed limit then the higher the work zone FFS, but the equation calculates differently.

(Edited July 24th, 2020 at 1:32 PM EDT)

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