Operational Performance of Signalized Intersections: HCM and Microsimulation Comparison

Delay at signalized intersections can be estimated by performing onsite measurements, applying analytical models, or using microsimulations. The Highway Capacity Manual 2010 (HCM 2010) methodology is considered to be one of the most convenient and practical analytical methods. HCM 2010 includes a set of different performance measures that thoroughly describe the operations for various travel modes, which makes it the favored methodology by local traffic engineers and planners. This study uses observed traffic data at major signalized intersections to estimate and compare different methods of estimating traffic delays at those intersections. A total of 16 intersections located within the City of Doha in Qatar are selected. For each intersection, traffic demand and signal timings data are collected during three peak periods. First, the turning movements, queue lengths, and geometric layout data are used to build these intersections within a microsimulation environment. To replicate real-life conditions, the microsimulation models were calibrated using several measurements that are observed in the field, such as average delay, average travel time, and intersection throughputs. The HCM2010 procedures are then used to estimate the delays at those junctions. A comparison is made between the simulated delays and those estimated using HCM 2010 procedures. The results revealed that the HCM 2010 method overestimates the calculated control delay at signalized intersections. Moreover, the results show that the default base saturation flow rate of 1,900 pc/hr/ln does not reflect the local conditions in the State of Qatar. Further investigations reveal that a base saturation flow rate of 2,300pc/hr/ln is better reflecting the real-life traffic conditions in Qatar.