But many of most important (and show-stopping) principles involved are the same, and those are what tend to cause delays and increase costs - things like running into unexpected geology, dealing with NIMBY's, the eminent domain process and so on.
He seems to think that, in between, his colleagues have been perfecting the fine forms of the art and polishing its many facets.
They (we) are. Want to see for yourself? Go to the Transportation Research Board annual meeting in Washington D.C.: http://www.trb.org/AnnualMeeting2014/AnnualMeeting2014.aspx
Except feats that were once fairly common, such as building the Hoover Dam under budget and two years ahead of schedule [1], are in the realm of the mythical these days.
You can say the same about the original elevated Boston Artery, the 19th century railroads, etc. The biggest difference between the mega-projects of old and today involve 1) the environmental process and 2) commitments to worker safety. It's fairly easy to build a project quickly when you don't care about splitting neighborhoods, killing/maiming workers and contaminating soil. The environmental process in particular has been a double-edged sword - it's done well in protecting the environment and communities, but it also provides means for anyone who doesn't like any facet of a project to significanty delay (or kill) it.