Quote:
Originally Posted by Quixote
I don't believe Purple should interline with Sepulveda; I just think it shouldn't be totally ruled out. That's why I'm against Bechtel's idea of narrower three-car consists. Three cars won't suffice once the line is extended down to the LAX/SoFi/Clippers arena arena. Just build the stations with the standard 450-foot platforms. Doesn't the use of a single-bore tunnel mean that they wouldn't have to build actual station boxes that drive up constructions costs? And if that's the case, why don't they spend more on an extra-large TBM to fit in a third or even fourth track for express services?
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There is a point of diminishing return on the size single bore tunnel. Once you get too large, two tunnels become cost effective again.
Also, I don't know if the geology under the mountain can support an "extra large" tunnel. I don't think anyone has done a subway tunnel big enough to fit 4 tracks anywhere in the world.