Comment by jtzhou

I think there are just a lot of intangibles so it's hard to compare mega projects, like the existing state of the subway where it is integrating into (like extensions), how many stations are being added, cost of labor, etc. I think comparing dozens of similar projects like the cost of replacing one street light, overpass or kilometer of highway from a non-US project, or even better within a single city in the same country, would be more informative.