NCHRP Synthesis 659: Automated Traffic Signal Performance Measures: Management, Operation, and Maintenance examines how state departments of transportation are using high-resolution traffic signal controller data to monitor, manage, and improve signal performance. Automated Traffic Signal Performance Measures (ATSPMs) enable continuous, data-driven oversight of traffic operations and maintenance, supporting more proactive and efficient decision-making. While the benefits of ATSPMs are well documented, adoption across state DOTs varies due to challenges such as funding constraints, equipment and technology upgrades, staffing capacity, and organizational readiness. The synthesis highlights current practices, including the use of both controller-based and crowdsourced signal performance measures. It also explores implementation barriers, funding strategies, staffing considerations, and examples of how agencies integrate ATSPMs into day-to-day operational and maintenance workflows.