Hong Kong is mostly granite, which is significantly more difficult to tunnel than the shale-like schist bedrock of manhattan...and MTR construction reflects thi

Hong Kong is mostly granite, which is significantly more difficult to tunnel than the shale-like schist bedrock of manhattan...and MTR construction reflects this fact, being more expensive per km than London, Paris, or Madrid. Even after this fact, MTR construction is still 50% cheaper than the average subway construction costs in the US.