How is capacity analysis performed for signalized intersections?

HCM methodology for signalized intersections: (1) Calculate saturation flow rate (s) for each lane group based on ideal saturation flow (1900 pc/h/ln) adjusted for lane width, heavy vehicles, grade, parking, turns, and pedestrians, (2) Calculate capacity c = s * g/C where g = effective green, C = cycle, (3) Calculate v/c ratio and control delay, (4) Determine LOS from delay (A: <=10s to F: >80s). Critical v/c ratio indicates overall intersection performance. Analysis identifies needs for geometric or signal timing improvements.