That's the delivery part. There is no room to stage anything on the site, so the mad 24/7 logistics nightmare has to happen during the entire construction proce

That's the delivery part. There is no room to stage anything on the site, so the mad 24/7 logistics nightmare has to happen during the entire construction process. There are 2 million more people in NYC now than there was in the old highrise heyday and that doesn't count commuters. That's a lot more traffic to have to negotiate. Not being able to physically deliver enough materials during the construction phase is an enormous slowdown. Coupled with the new smaller footprint/higher elevation slowdown it winds up being a slog. You can only fit so many workers in a given area. There are other differences that add time and complexity that the old buildings didn't have to deal with as much as well, like the thousands of miles of additional cabling that goes in now for higher electric loads and data. I would also imagine that inspections weren't near as thorough and time consuming in the past. It's death by a thousand cuts. Hundreds of little things add a little time and complexity and it all adds up.