How is optimal signal cycle length calculated using Webster's formula?

Webster's formula for optimal cycle length: Co = (1.5L + 5)/(1 - Y), where L = total lost time per cycle (sum of start-up and clearance losses), Y = sum of critical flow ratios (v/s) for each phase. This minimizes total delay at the intersection. Green splits are allocated proportionally to critical flow ratios. Practical considerations include minimum pedestrian crossing times, coordination requirements, and maximum cycle length limits (typically 90-120 seconds). Cycle length increases with higher traffic volumes.