How is traffic signal coordination achieved on arterial roads?

Signal coordination creates green waves allowing vehicles to progress through multiple signals without stopping. Key parameters: common cycle length (all signals same cycle), offsets (time difference between green starts), bandwidth (continuous green time through system). Coordination achieved through: time-space diagrams to visualize vehicle trajectories, optimization software (SYNCHRO, TRANSYT), and real-time adaptive systems. Half-cycle offsets may accommodate two-way progression. Coordination breaks down at high v/c ratios or long distances between signals.