Ahead of schedule based on an adjusted schedule during construction. They are slightly behind the originally planned schedule (a couple years).
Obviously this is still a very well executed project overall.
Obviously this is still a very well executed project overall.
"This rock is too solid to drill through with our machines!" – "Ok, for now let's just drill around it and make it an underground rollercoaster instead of a railway, we can get back to the original design later!"
However, here “ahead of schedule” is used as a, well, I guess compliment and for that it’s important to know the context. That they adjusted the schedule is obviously not at all a problem and, as I said, for a project this big the couple years it took longer aren’t really that relevant even.