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VDF functions

Francis King
VDF functions was posted on June 29th, 2012 at 9:15 AM EDT
regarding Chapter 11: Basic Freeway Segments

Speed flow curves have been provided, e.g. Exhibit 11-15.

It would be really useful if coefficients were provided for a range of road types, and for a range of speed-flow curves and volume-delay functions. Graphs are generally less useful than coefficients for calculations.

Gustavo Riente de Andrade
TECTRAN - T├ęcnicos em Transportes ltda
RE: VDF functions was posted on August 11th, 2012 at 11:43 PM EDT

Agreed. In a series of training courses I,ve been giving for highway professionals, that was a recurrent feedback they give me. People would like to have VDFs to do HCM calculations in an Excel spreadsheet. In my master thesis, I derived a basic formulation which can generate any speed-flow curve for a given value of FFS (not necessarialy rounded) for freeways and multilane highways. It's been proving very useful now.

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