Revised Version of the Automobile Level-of-Service Methodology for Urban Streets in the Highway Capacity Manual 2010
The Highway Capacity Manual 2010 (HCM 2010) contains a significantly revised automobile analysis and level-of-service (LOS) methodology for arterials. This study compared the arterial LOS results of the HCM 2000 and HCM 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, all in Florida, as well as data received from the Florida Department of Transportation Districts 2 and 3. The HCM 2010 results showed that for shorter, lower-speed arterial segments [such as in central business districts (CBDs)] it was not possible to obtain LOS Ratings A or B. Therefore, many 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 revisions of the HCM 2010 methodology to find an approach that would not be as punitive to arterials with shorter segment lengths and that would 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 consisted of the following: the use of two classes instead of one (on the basis of the posted speed); the use of the average travel speed as the service measure instead of the ratio of the average travel speed to the base free-flow speed; and the setting of the free-flow speed to equal the posted speed plus 5 mph, instead of using the free-flow speed computations in the HCM 2010 methodology.