Hacker Newsnew | past | comments | ask | show | jobs | submitlogin

Concrete is about two tons per yard. The legal limit on most trailers is about 20 tons (40,000 pounds, the trailer is about 40,000 for the legal limit of 80,000 pounds). So you can get about 10 yards of concrete in one go; you can use specialty trailers to get higher numbers, but even if you double it to 40 tons, that's still only 20 yards.

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.



If there was an interstate running directly from San Francisco to Los Angeles along this route...

Umm, that's kind of the point. It's called I-5.


I guess we can agree that we don't need to have this discussion, as I-5 runs the entire route where the pylons would need to be installed.


> a 4' x 4' x 8' ecology block is about five yards

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)




Guidelines | FAQ | Lists | API | Security | Legal | Apply to YC | Contact

Search: