MUTCD's Warrant 2 change?
MUTCD's Warrant 2 change?
Question about Warrant 2 (Four-Hour Vehicular Volume) from MUTCD's Section 4C.01 (https://mutcd.fhwa.dot.gov/htm/2009/part4/part4c.h...):
Figures 4C-1 and 4C-2 show curves that vehicles per hour data points are scattered across - if they cross the line, the warrant is considered satisfied.
Suppose I wanted the curves for Warrant 2 to be for a Three-Hour Vehicular Volume. How would I determined the change in the position of the curves on the Figures? I'd be counting the 3 highest hours instead of the 4 highest hours, but all the worksheets show the curve already set (see attachment, pg. 3): https://files.engineering.com/getfile.aspx?folder=...
Thanks for help!
Edit: FHWA MUTCD page had this to say about origin of curves:
"Q: How can I obtain the formulas on which the curves in the graphs for signal warrants 2 (four-hour warrant) and 3 (peak hour warrant) are based?
A: The formulas are not readily available. Those graphical MUTCD signal warrants were based (loosely) on modeling and simulation research in the 1970s that developed a large number of curves. The curves that ended up in the MUTCD don't exactly match what's in the research report, as a result of massaging that was done to obtain consensus agreement on the new warrants from the practicing traffic engineering community at that time. The developers of commercial software products that "automate" the signal warrant analysis process most likely created formulas or equations by working backwards from plotted points on the curves and/or using "curve fitting" programs. Also, the HTML version of Part 4 on FHWA's MUTCD website has tabular formatted charts of the graphs that are part of the Section 508-compliant "text descriptions" of the figures and graphics. Those descriptions were developed specifically to meet Section 508 of the ADA law, which requires the federal government to make accessible to blind and visually-impaired persons any material that is posted in electronic format on websites. The firm that developed the descriptions for FHWA did what anyone could have done---plot values of some points on the curves and put them into tabular form that a visually disabled person's HTML-reader software can read. However, it must be recognized that these plotted point numerical values have no official or legal basis and are just estimates provided for user information only. A direct link to the HTML version of Chapter 4C is: https://mutcd.fhwa.dot.gov/htm/2009/part4/part4c.h...."