This book contains peer-reviewed proceedings of the 2026 13th International Conference on Geological and Civil Engineering (ICGCE 2026), held in Fukuoka, Japan, from March 6–8, 2026. The conference served as an ideal international forum, bringing together leading researchers, engineers, and industry professionals to exchange cutting-edge ideas, share research outcomes, and foster new collaborations. This book features high-quality contributions covering a broad spectrum of topics, including geo-technical engineering: performance assessment, testing, and management, multi-scale mechanical behavior and seismic performance of engineering structures, resource recycling and material innovation in sustainable civil engineering, sustainable water management and coastal infrastructure, intelligent traffic systems: pedestrian behavior and computer vision–based monitoring, etc. This book is an essential resource for researchers, scholars, practitioner who are engaged in researches and studies in the field of Geological and Civil Engineering.