“We need to perform regular scans to see whether what we’ve built differs at all from the construction plans, or if there are any problems with some section of the tunnel. Through regular scanning, you can prevent those issues from popping up. And if we can perform those scans without …

"We had the circuit breaker, which had an issue with the electrical protection. In order to remove that breaker, it would be too hazardous for a human to go in there, so we’d have to make a larger outage to a bigger system. It probably would have taken several months …