MAITE

The Second Transportation Student Research Symposium

Abstract Detail

Name	School	Title of presentation
Joshua Seeherman	NU	A LOS comparison between HCM theoretical values and actual freeway data

The Texas Transportation Institute reported in January 2005 that the average lost time for commuters stuck in traffic has tripled in the last five years, an indication of how congestion is affecting our national economy. Thus, it is imperative to utilize our best design theories to improve design of our congested freeways. In the US, the Highway Capacity Manual has been the standard for planning and traffic analysis. However, the HCM may not accurately represent conditions during the peak hour when freeways are congested. To compare with HCM theoretical values, flow, density, and speed was calculated from actual highway sections with grades over 2% from data agglomerated from FHWA aerial photography. The result of the first section analyzed demonstrated that there was a significantly higher density than predicted by the HCM. This may be due to a number of issues; the underestimation of the effect of grade, the selection of a high base free-flow speed in urban conditions, or the failure of the theory to work during congested conditions. The results of the analysis reveal that the HCM may not adequate in the increasingly congested freeway system and the HCM factors used in theoretical calculation may have to be revisited.

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Last updated January 9, 2009