That tactic was heavily used in the construction of "The Big Dig" which relocated a congested section of elevated roadway into what would become an equally-congested tunnel below the original elevated structure. I hope they poured the foundations well enough to support the next expansion project which will be the rebuilding the elevated structure to, once again, relieve congestion.FranTastic444 wrote: ↑Mon Nov 25, 2019 11:45 pmOver the last few months I've enjoyed watching the clearing of a site next to our office (an old concrete multistory car park) and the insertion of very deep slurry walls to act as the foundations for what will be the second tallest building in downtown Boston. This video gives an idea of what was going in (it is the same company - East Coast Slurry).
The place in that project that I referred to was the I-90/I-93 interchange just south of South Station Terminal. This congested area joins two of the major motorways of Boston fairly seamlessly in a very congested space in full 3-D glory underground, and with the added complication of a very heavily-travelled railway line at the surface. East/west from surface downwards is the railway that connects Boston to New York, Route I-90, in a depressed tunnel entrance to the tunnel under the Fort Point Channel, and North/South I-93 beneath that for grade-separation of N/S and E/W traffic. Ramps and connectors were required for full access in all directions. And all of this had to be done without disrupting (too badly) what was happening at the surface.
From the train I commuted on from Worcester to Boston, I passed over this twice per day -- and revelled in it. That was the last job I had where I actually felt I was making a difference in the world, and it was magical. Each day I'd see the drawings being created by the engineers and architects on the computers I kept running -- and each day, I'd witness the drawings produced months before become real beneath me. This is, indeed, the stuff of dreams.
It's at least as effective as piles, and, if done really well, likely even better.Apparently this method of construction is well suited to the geology of the Boston area.