Intelligent Pedestrian-Crossing Illumination for Sustainable Smart Roads and Urban Mobility: Safety, AI Reliability, Inclusion, and Environmental Trade-Offs

Pedestrian crossings are essential elements of sustainable road design because they mediate interactions among motorized traffic, active mobility, and users with diverse abilities. At night, poor pedestrian visibility, delayed yielding, excessive approach speed, and inaccessible or poorly coordinated infrastructure can turn a compliant crossing into a high-risk conflict point. Intelligent pedestrian-crossing illumination integrates approach-specific photometry, warning devices, sensing, communications, edge processing, and artificial intelligence to adapt the road environment to pedestrian presence and traffic conditions. This critical review evaluates such systems as people-centered smart-road infrastructure rather than isolated lighting devices. Evidence is synthesized across road-safety performance, human factors, sensing and AI reliability, inclusive design, operational energy, life-cycle burdens, economic considerations, and ecological effects of artificial light at night. Studies show that improved pedestrian contrast, appropriate luminaire placement, vertical illumination, and timely warnings can enhance detection, yielding, approach speed, and stopping behavior. However, current evidence is heterogeneous and dominated by simulators, staged pedestrians, single-site demonstrations, short monitoring periods, and surrogate outcomes. Critical aspects such as crash reduction, adverse-weather reliability, accessibility, resilience, life-cycle performance, and biodiversity impacts are rarely assessed together. Three complementary outputs are proposed: an evidence-maturity framework, a multidimensional trade-off framework, and a stage-gated pathway for context-sensitive deployment.