Abstract: Discusses the problems of the reliability analysis for tunnel structure by way of conventional stress field. Describes how the supersonic technique and geologic radar worked to detect/evaluate the concrete lining thickness and quality of an expressway tunnel. Based on the monitoring/measuring data obtained from a tunnel in service in Northeast China, a new way was proposed to evaluate comprehensively its structural reliability. The results showed that this method is highly practical and available to use for other road tunnels, and it is feasibly adaptable to lengthening the service life of road tunnels and reducing the costs for structural maintenance/reinforcement.