I can't say I'm overly surprised at this article about safety at Boston's 'Big Dig'.
Having been 'in' tunnels before and following the project reasonably closely, I realised things may not have been properly thought out the second they announced they were pumping liquid nitrogen into the ground around the workface to ensure support for the surface.
$14.6 billion.
You could do a lot with that.
Although I'm never convinced how much at fault the engineers are as opposed to the managment.