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Interpretations & Errata?

Jeanne Bowie
Kinney Engineering
Interpretations & Errata? was posted on October 19th, 2011 at 5:37 PM EDT
regarding Chapter 18: Signalized Intersections

I am analyzing an existing signalized intersection with a shared left turn/through lane where the left turn is permitted and opposed by two lanes. I was unsatisfied with the results I was getting, as the HCM2010 analysis indicated that the LOS was F, even though the intersection is operating well. After updating my HCS2010 program with McTrans' latest update (10/1/2011), I receive the following message when opening the intersection file:

ERROR: The Highway Capacity and Quality of Service (HCQS) committee has stated that permitted left turns, when opposed by two or more lanes including a shared L+T lane, are not modeled correctly by the HCM Chapter 18/31 procedures. The HCQS committee is working on a solution.

If this is the case, why is there no notice of this under interpretations and errata? When I was having trouble believing the analysis, I looked here first and found nothing!

Scott Washburn
University of Florida
RE: Interpretations & Errata? was posted on October 28th, 2011 at 11:11 AM EDT

Interpretations and errata go through a committee-wide approval process. Once a suitable solution to this issue has been developed by the signalized intersection subcommittee and approved by the full committee, it will be added to the errata section.

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