Institute of Transportation Studies at UC Berkeley

Traffic performance metrics such as delay and Level Of Service (LOS), which are well documented in the Highway Capacity Manual (HCM), have been widely used by most of the transportation consulting companies, public agencies, and etc. For arterial delay analysis, prevailing commercial tools like Synchro have adopted the method proposed by the HCM, which is rooted in the Webster’s delay calculation proposed more than 50 years ago. The LOS is obtained using a lookup table that assigns a certain grade (from A to F) to the estimated delay according to its value. Without knowing detailed vehicles trajectory profiles, this kind of delay calculation method relies on macroscopic queueing theory and assumes certain types of arrival patterns. As mentioned in the State Bill 743 (SB743) and the memo entitled Preliminary Evaluation of Alternative Methods of Transportation Analysis issued by Governor Brown’s Office of Planning and Research on December 30, 2013, current calculation of LOS is difficult and expensive. Particularly, as will be illustrated in Section 2, the state-of-the-practice calculation of delay and LOS for local intersections is very complicated and has limitations