The North Carolina Level of Service (NCLOS) program is a planning-level highway capacity analysis tool developed for NCDOT under a previous project. The program originally used methodologies in the 2000 Highway Capacity Manual (HCM), along with specific default parameters from North Carolina data, to determine level-of-service (LOS) threshold “capacities” for freeways, multilane highways, two-lane highways, and arterial streets. Shortly after the release of the HCM 2010 edition, the NCLOS program was updated in a follow-up project. NCLOS is unique in that it provides a graphical display of the measures of effectiveness (MOE) plotted against AADT for each facility type. Users see best case, default case, and worst case curves, plus a highlighted curve for the LOS selected for the analysis.
The NCLOS program is being used extensively in planning applications within NCDOT. Output capacities are used in travel demand forecasting models and in developing Comprehensive Transportation Plans (CTP). Output values can also be used in the statewide travel demand model. Currently the tool is also used to provide data for the Performance Metrics Dashboard and is used as a scoring component in the Strategic Prioritization Process and Urban Loop Prioritization Process.
In early 2016, the HCM 6th Edition will be available for transportation facility analyses. There are significant and important improvements for many of the methodologies in the new HCM based on the most recent national research over the last 5-6 years. As with previous editions of the manual, the HCM 6th Edition will become the standard for determining capacity of most highway facilities. NCLOS was re-programmed to incorporate these new methodologies and other enhancements to remain current with the state-of-the-practice.
This research project analyzed new traffic count data available from the Traffic Survey Group and found that travel patterns had not significantly changed, but did recommend default values for new variables that did not exist in previous editions of the HCM. The improved NCLOS software can be used to update the Comprehensive Transportation Planning Manual to bring the default tables and guidance up to speed with the HCM 6th Edition.
