[sixtofour]

"If manpower is expensive, you buy prefabricated components and only do the final assembly on site."

Not infrastructure, but that's exactly what Boeing has done for years, assemble airplanes out of prefabbed subassemblies.

When Boeing gets a contract to sell planes to, say, China or Japan, part of the deal is often that the subassemblies (wings, body sections, whatever) are made in that country, shipped to the US and assembled by Boeing.

Airplanes are a more controlled and regular construction environment than highways, but I don't see why it won't become more common. Residential and commercial buildings too, I suppose. Suburban houses are already cookie cutter these days.