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Default Values?

Heather McColeman
Ohio DOT
Default Values? was posted on April 6th, 2012 at 1:08 PM EDT
regarding Chapter 10: Freeway Facilities

The bottom of page 10-40 references Chapters 11, 12 and 13 for specific default values per analysis method. However, only Chapter 11 (page 11-21) contains default values. Chapters 12 and 13, pages 12-25 and 13-28, respectively, refer the user back to Chapter 10 for default values. Is this an oversight or are there default values placed elsewhere in the Chapters? I am specifically asking about PHF default. (My question acknowledges that the use of default values can affect the reliability of the results. I still find these cross references in the manual confusing.)

(Edited April 6th, 2012 at 1:04 PM EDT)
Paul Ryus
Kittelson & Associates, Inc.
RE: Default Values? was posted on May 31st, 2012 at 7:06 AM EDT

All of the freeway-related default values (except for a few ramp-specific, use-only-if-necessary values on page 13-28) were derived from NCHRP Report 599 and ended up in Chapter 11 in the table on page 11-21. Chapters 10, 12, and 13 should reference the default values list in Chapter 11. I've forwarded your comment to the TRB Highway Capacity Committee for consideration as a future correction.

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