I saw in a paper that gave reasons tunneling projects were expensive listed labor as a larger fraction than you would think. Consider cars. Your $30,000 car pro

I saw in a paper that gave reasons tunneling projects were expensive listed labor as a larger fraction than you would think. Consider cars. Your $30,000 car probably costs $60,000 to operate over it's life. Likely more. Not surprise me if tunneling is the same. Operating costs dominate. Then consider the Bertha problems in Seattle. Two year delay because they needed to dig a rescue pit to get at it after it broke down. Ask would you want to start a tunnel project with an 'used' TBM? Likely not.