About YAMAMOTO TSUTOMU
About 東京地下鉄
About Subway
About underground railway
About railway tunnel
About rehabilitation management
About periodic test
About deterioration (superannuation)
About variation
About image
About digital image
About salt damage
About concrete
About degradation (alteration)
About lifetime extension
About Tokyo Metropolis
About neutralization
About tunnel transformation state
About visible imagery
About Tokyo Metro
About Tunnel maintenance and incidental equipment,and others
About Track maintenance,prevention of railway disasters
About 東京
About メトロ
About トンネル
About 維持管理
About 長寿命化