Research the Big Dig. Most of the interstate was built 50+yr ago when the administrative overhead of such projects was far, far lower. The states basically sa

Research the Big Dig. Most of the interstate was built 50+yr ago when the administrative overhead of such projects was far, far lower. The states basically said "here's where it's going" and did it without much local input, environmental assessment, etc, etc. Government also was far less risk averse in those days (so more stuff was done in house at cost). The interstate is actually a great example of how costs have increased over time since it was mostly built over a 30yr period.