Abstract The application of DER evaluation method of structure inspection and the operation of visual scan database for evaluation of tunnel structure safety in TMRTS are introduced. The DER evaluation method is widely used in bridge structure inspection. Taipei Rapid Transit Corporation (TRTC) adopts the DER evaluation method in ordinary and periodical tunnel structure inspections. The basic structure information，results of structure inspection and maintenance records of TRTS are managed in a unique Structure Management Information System. The evaluation of tunnel structure safety should be carried out by the professional engineering consultants，who evaluate the potential defaults of the tunnel structure. In the meantime，the visual image of entire tunnel surface can be scanned into digital files and recorded by using the digital image scan technology. The visual image will be used for the reference and comparison of future structure safety evaluation.
2004, Vol. 23 
