One of the better-written reviews (almost certainly seen here before) of the "why does it cost so much to build stuff in the US" ... [www.vox.com]

Many others can be found, but many have right-wing axes to grind so be careful.

An interesting paper (PDF) ... [papers.ssrn.com]
And another article, along the same line: [www.strongtowns.org]

Bottom line seems to be: our procurement regulations and funding practices are wrong. We reward graft, extortion, change orders, and ballooning costs rather than penalizing it. FWIW, it's not just transportation - have you ever looked at health care? Here's one obvious example: engineering and overhead costs as a percentage of construction cost; how could that possibly go wrong?