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Re: Seismic hydraulic mud in the Newhall Tunnel
Author: mook
Date: 06-01-2016 - 17:36
Any tunnel is subject to unanticipated problems, which is why (along with the cost) they're avoided in general. But sometimes they are the best (or only) solution. And there is no way to get a railroad out of LA to the Central Valley without boring tunnels - the higher speed the line is designed for, the longer and more costly the tunnels.
The major seismic zones in and bordering the San Gabriels are moderately well known and can be designed for; besides, the ones within the range don't have (at least a recent) history of frequent major movement unlike the ones bordering the range. Minor ones are likely to cause problems during construction, but if suitable contingencies (based on allowances for the majors) are provided for it can still work. The Alps are a fairly unstable mountain range produced by seismic zones too, and I strongly suspect that odd things happened at times in the big project - the Swiss simply anticipated them and had appropriate responses ready (rather than, as in the U.S., stopping everything and calling for extra work and change orders == PROFIT!).
For that matter, Spain is earthquake country too and most of their HSR lines just punch through modest mountain ranges almost without a thought about avoiding them. Also large bridges to manage the grade changes. They do, of course, have "shared" lines with the conventional rail in places where it hasn't been practical to build true HSR yet, and unfortunately a driver several years ago hit a curve too fast in one of those shared zones after missing several slowdown signals as the HSR zone ended; eerily similar to the Amtrak NEC wreck last year. Anyway, a tunnel through either the Tehachapis (though there's somewhat less information available about what's inside them) or the San Gabriels for HSR is eminently doable if the money can be found.
And Just Do It for the Pasadena thing. The current tunnel proposals are quite benign in their effects on So.Pas. especially compared to some of the stuff I saw 30+ years ago. Ban trucks if you have to, forcing them over to 605, but that would (in a toll scenario) greatly extend the payoff period if not making it "forever." A lot of trucks do need to make it through, and the detour would guarantee higher truck emissions in the Basin pretty much forever.
The major seismic zones in and bordering the San Gabriels are moderately well known and can be designed for; besides, the ones within the range don't have (at least a recent) history of frequent major movement unlike the ones bordering the range. Minor ones are likely to cause problems during construction, but if suitable contingencies (based on allowances for the majors) are provided for it can still work. The Alps are a fairly unstable mountain range produced by seismic zones too, and I strongly suspect that odd things happened at times in the big project - the Swiss simply anticipated them and had appropriate responses ready (rather than, as in the U.S., stopping everything and calling for extra work and change orders == PROFIT!).
For that matter, Spain is earthquake country too and most of their HSR lines just punch through modest mountain ranges almost without a thought about avoiding them. Also large bridges to manage the grade changes. They do, of course, have "shared" lines with the conventional rail in places where it hasn't been practical to build true HSR yet, and unfortunately a driver several years ago hit a curve too fast in one of those shared zones after missing several slowdown signals as the HSR zone ended; eerily similar to the Amtrak NEC wreck last year. Anyway, a tunnel through either the Tehachapis (though there's somewhat less information available about what's inside them) or the San Gabriels for HSR is eminently doable if the money can be found.
And Just Do It for the Pasadena thing. The current tunnel proposals are quite benign in their effects on So.Pas. especially compared to some of the stuff I saw 30+ years ago. Ban trucks if you have to, forcing them over to 605, but that would (in a toll scenario) greatly extend the payoff period if not making it "forever." A lot of trucks do need to make it through, and the detour would guarantee higher truck emissions in the Basin pretty much forever.
