Lighting the way: Strategic solutions for smarter traffic signals

Effectively maintaining traffic signals enhances driver safety and cuts costs for public agencies.

Illinois Center for Transportation and Illinois Department of Transportation partnered to improve traffic signal assessment and maintenance practices across Illinois in the joint project, R27-251: Optimum Traffic Signal Condition Assessment and Strategic Maintenance Planning.

Ryan Fries and Yan Qi, Southern Illinois University Edwardsville professors, led the project with IDOT’s Kenneth Davis, electrical services supervisor for District 8, and Kyle Armstrong, engineer of operations.

Illinois’ 6,800 traffic signals have various electrical and structural components, making maintenance complex. This project equipped IDOT with consistent data to prioritize repairs and replacements more effectively.

Fries and Qi developed an evaluation method that will shift transportation agencies from reactive to proactive maintenance, reducing the risk of malfunctions and lowering long-term costs. They developed standardized assessment procedures for 34 components, categorized into good, fair, poor or critical conditions.

Collaborating with Illinois traffic signal technicians and engineers, they incorporated best practices and Illinois-specific data to estimate the components’ life span and to create a roadmap for future maintenance needs.

“An unexpected traffic signal failure can be dangerous to travelers, cause delays, and add expenses to public budgets,” Fries said. “This research recommended a method to help agencies identify poor conditions and perform maintenance or replacement before a failure occurs.”

The standardized procedures allow for consistent assessments statewide of electrical and structural components as well as provide estimates of expected life cycles.

“This approach would allow agencies to better assess the condition of traffic signal components, whether they be electronic components, poles, or the signal indications themselves, to help establish when they should be repaired or replaced,” Armstrong said.

Budget constraints often complicate planning for effective maintenance. According to Davis, budgets for signal equipment and maintenance vary widely, making it difficult to plan for repairs and replacements. Data collected in this study may support funding requests with evidence of component condition and life cycle.

The complexity and 24/7 operation of signal systems add another layer of difficulty, making life cycle tracking critical for ensuring continued safe operation.

By using the recommended preventive strategies, IDOT and local agencies can extend signal life span and reduce unexpected failures, leading to fewer traffic disruptions.

This proactive approach helps optimize budgets, reduces emergency repairs and improves signal performance. Armstrong noted the research would help allocate maintenance funds more efficiently while improving safety for motorists.

The project lays the foundation for integrating traffic signals into broader infrastructure management systems, ensuring they are evaluated alongside other critical assets.

Fries sees this as the first step in a larger initiative.

“Transportation agencies can now use a consistent method to evaluate the condition of their traffic signals,” Fries said. “The results can help identify any components in a critical condition, avoid unexpected failure, and support proactive management of these important transportation assets.”

The recommendations offer a path toward improving traffic signal reliability statewide, making roads safer and helping agencies operate more efficiently.