actually they are based on ww1 britan I think. Just look at their armor and tactics

Err the NCR is more than an army. This topic is not about that.

But yes, if they can get railroads across the USA - the rebuilding should be more or less complete infrastructure wise.

I don't think the NCR can build railroads they use pre-war railroads because where would they smelt the iron the nearest working refinery is in the Pitt.

I think that creating a new steelworks isn't something that would be all that difficult. Besides, the Powder Gangers were working on creating a railroad weren't they?

Melting iron is all but hard. But getting it in large amounts could be hard since there isn't all that much in the us as far as I know.

California has iron and there is always good old recycling.

Think of the sheer amount of old girders you could dig up out of the wreckage of LA alone.

There's also coal to be mined in California and quite a lot of it in Southern Oregon (also NCR territory).

Well if you look at the old maps of frontier USA when the continental railroad was being built you can see the towns and cities that sprung up around the railroad, so basically you set up a construction crew, give it a decent military unit, and pioneers follow along the line and build towns along the line to support the railroad, its a story of grand old pioneering americans except not building the US but rebuilding.