perhaps you can pour sections and truck those in, but there's no way in hell you're moving a precast that size on anything that doesn't float.
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.
While I certainly can't say anything for the economy of long distance shipping of giant concrete pylons, I can confirm they do get trucked around a lot in the Dallas area. The overpass ribs are basically hooked to a small truck attached to the cab with a small truck on the other far end.
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...)
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.
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.