This paper considers techniques for inferring the cause of deformation in the lining of tunnels by the extracted normal type of cracks using a Tunnel-Lining Crack Index ("TCI") calculated from on internal elevations, of cracks found in the lining of road tunnels administered by East Nippon Expressway Company Limited, Central Nippon Expressway Company Limited and West Nippon Expressway Company Limited (together "NEXCO"). As a result, deformation inferred to be due to internal causes and external causes was able to be classified quantitatively. Further, for tunnels deformed by external forces, the interrelation between the configuration of cracks and deformation of the tunnel cross section was able to be determined by implementing measurement of the tunnel cross section using a Mobile Mapping System.