It's easy to say that something will cost (eg.) $1bn if it's built in 2 years, but when most of that is labour and bureaucracy starts getting involved, the labour gets put on hold for a year or two whilst still getting paid. Suddenly the overall cost of the project has tripled without anything actually changing, except some bureaucrat sticking their oar in.
Maybe I'm just cynical, but the labour costs seem to be one of the least well defined aspects of this proposal. It's easy enough to make it look cost effective compared to existing rail projects when you don't factor that in.
Afterall do you really think that the HSV with two steel rails is costing $80bn+ because of the price of the components? Although I don't really know the specifics, I find it hard to believe that the rights of way cost that much either. It's usually down to contracting an entire company worth of engineers for 10-20 years that ramps up the costs.
For scale, you know those 4' by 4' by 8' blocks of cement you see all over the place, used for erosion control and the like? They're called ecology blocks, they're about $20 each FOB the cement plant. You want them shipped? A lowboy can carry two or four at a time without exceeding load limits. When I looked into buying a couple hundred, having them shipped about sixteen miles, it was going to cost hundreds per block to truck it out plus renting a crane to unload/place them.
Those are tiny blocks with almost no rebar, no engineering, no preload, nothing.
Again, dunno if it's feasible over long distance, but it's certainly done. (Though Texas has a certain affinity to overpasses that borders on the pathological, fun as they are to bike over...)
a 4' x 4' x 8' ecology block is about five yards. So let's picture the pylon having a 4' x 4' base that sits on granite, requiring no foundation. The pylon is going to max out at 16 or 32 feet tall if we're required to stay within the load limits.
furthermore, when you see those ribs moving around, they're moving around on interstates or state roads of solid construction. If there was an interstate running directly from San Francisco to Los Angeles along this route, we wouldn't be having the discussion. Building such a road to deliver precast sections is quite the endeavor.
I stand by my original claim that these would need to be cast-in-place.
Umm, that's kind of the point. It's called I-5.
That's just brilliant. (for the rest of the world 1,201,202.4m is 3.5m^3 and density of concrete is around 2400 kg/m^3)
It's just fascinating to me that the most expensive thing (in aggregate) is also the "dumbest" part.