This study introduces a human-centered and transdisciplinary engineering-centered “4D” design model, comprising Discovering Service Touchpoints, Defining Service Sore Points, Depicting User Experience, and Design Idea Development phases, which are based on service encounter discovery and peal-end rule. The systematic travel experiment involving 30 volunteers across six city tours was conducted to analyze user behaviors and needs. Emotional change curves are utilized to optimize peak and end of travel experiences. The findings validate the 4D model for redefining service encounters and leveraging the peak-end rule for the improvement of public transport services.