Well, I'll give my commentary.
Imagine the people running the project, do testing on the line, running empty trains along it for 2 and a half years, to verify that everything is perfect, and nothing wrong will happen when the line opens.
Imagine the line finally opens, and within the first few months numerous problems occur. Collisions, a derailment, a mix of human error and system error.
Imagine each problem is fixed as it happens. Now and then, shuttle buses run in place of the trains for a few hours.
If it's serious, they may halt the line for a day. But it's not permenant, they don't give up and shut down the line unnecessarily for an extended period.
Just like they do on all the other lines. Life goes on.
And then we may look back and wonder if the 2 and half years of testing was ever needed.