Fall 2012 Seminars
Presenter: Seckin Ozkul, doctoral student
Title: A Revised Version of the HCM 2010 Urban Streets Automobile LOS Methodology
Abstract: The Highway Capacity Manual (HCM) 2010 contains a significantly revised automobile analysis and level of service (LOS) methodology for arterials. This paper compared the arterial LOS results of the HCM 2000 and 2010 methodologies for an experimental set of arterial segments and analyzed the effects of the revised methodology. In addition, existing Florida field data sets were also analyzed with arterial segments obtained from Gainesville, Tallahassee, and Tampa, as well as data received from FDOT Districts 2 and 3.
The HCM 2010 results showed that for shorter/lower speed arterial segments (such as in central business districts) it was not possible to obtain LOS A or B. Thus, many of the CBD arterials that had good LOS values under the HCM 2000 methodology would now have moderate to poor LOS values. Consequently, the research team tested several different revisions of the HCM 2010 methodology to find an approach that would not be as punitive to arterials with shorter segment lengths and provide a good balance of LOS values across a range of segment lengths, posted speeds, and traffic demands. Suggested revisions to the HCM 2010 methodology that allowed this objective to be achieved consist of the following: using two-classes instead of one (based on posted speed), using average travel speed as the service measure instead of the ratio of average travel speed to base free-flow speed, and setting free-flow speed equal to the posted speed plus five miles per hour instead of the free-flow speed computations in the HCM 2010 methodology.