>A fun question: of these projects, which required a long time, and which could have been greatly accelerated?

Pretty much everything on the list is a research study of a long-term process that is inherently impossible to accelerate.

From the list, only the Second Avenue Subway and the Sagrada Familia unambiguously qualify as projects that could be greatly accelerated. The SAS was not under active construction for the vast majority of the time between 1942 and 2017 — actual construction only happened for a couple years in the early 70s, then another couple years in the late 80s, and finally from 2011-2017. The fits and starts were due to a combination of bureaucratic red tape, economic woes, and gross incompetence. The Sagrada Familia has also seen only intermittent construction over the last century, primarily because of lack of funding.