Presumably everything else is on track, but when it comes to geotechnical engineering, stabilizing earth is challenging, and the engineers appear to want to wait more than 3 or 4 days after the cave-in to see if their method of stabilization (whether they used these neat ground screws, thicker walls, or a pairing) is stable and ready for non-employees to be near.
That article mentions absolutely nothing about a cave in. I wasn't disputing the delay thing (definitely an issue with any project of Musk's), but claiming that there was a cave in requires a legitimate source.
I did more research and still came up blank - I saw a number of headlines talking about "boring company caves in" - but they use it as a metaphor for them abandoning plans to extend the tunnel significantly. Not an actual cave in.
Presumably everything else is on track, but when it comes to geotechnical engineering, stabilizing earth is challenging, and the engineers appear to want to wait more than 3 or 4 days after the cave-in to see if their method of stabilization (whether they used these neat ground screws, thicker walls, or a pairing) is stable and ready for non-employees to be near.