I can’t place exactly where those mileposts are; it’s been over 10 years since I moved from Nevada.
As far as double tracking the former WP goes; there are two really tough spots. Silver Zone pass has several miles of tight curves and rock cuts that would require a massive amount of blasting/digging. (Although I always wondered if a much shorter - but steeper - bypass could be built for eastbound traffic; staying entirely to the south of the freeway.) There is also the tunnel through the Pequop range. Really expensive to put in a second bore; (or a valley bottom cut just to the south of the existing tunnel?) or a permanent single track choke point.
A question that has bounced around in the back of my mind (lots of spare room there, ya know…) about this-why not replace the fill with a new bridge/trestle? After all, it has already been done so it doesn’t seem to be an insurmountable task. My layman’s impression is that steel or concrete pilings are not limited in length the way wooden piles are and ought to be able to reach sufficiently stable ground* to support tracks and trains.
Would the extreme salt environment be too harsh for such materials? Steel and concrete structures around the world’s oceans exist that have been there for decades (FEC’s Key West Extension comes to mind). Or do the extremes of the Great Salt Lake take us into another realm of chemical reactions?
Of course, it could simply be a case of cost but I wonder how great (or little) the differential is compared to the constant shoring up the present fill has needed and will need.
*Were there settlement problems with the original structure?
The water in the Great Salt Lake contains appreciably more salts than seawater, I believe that average salinity is about 28%. Since the lake is located in an arid climate, the salts get left behind very quickly when the water evaporates. Anybody who has bobbed around in the Great Salt Lake will vouch for this fact.
The higher salinity also means that the water is denser, so waves pack a lot more wallop when they hit something.
I don’t know the specifics of the GSL basin, but those in the “Basin and Range” could have thousands of feet depth of sediment, although hopefully the sediments would be de-watered enough for support at shallower depths. Complicating things could be interbedded salt, gypsum, etc. which could dissolve, or deform under load.
Watched a segment on the History Channel last night about using Styrofoam as a building material in the construction of highways over less than optimum ground conditions - sinks and other unsteady soil conditions.
The alleged selling point was that the Styrofoam blocks, when used as a part of the sub-grade system provided a steady base that was thousands of times lighter than using normal rock & dirt fill materials to perform that same function and in being lighter did not exert the continual forces that the heavier methods did up on the suspect ground and thus didn’t develop the overall sinking of the roadway over time that has been happening with traditional methods. Segment stated that the Styrofoam ‘sub-grade’, depending upon conditions could be anywhere for a foot or two to twenty feet or more in depth.
I am not a CE and have no idea if this form of technology could help in this instance.
@rdamon - nice link! That must have taken quite a hike and quite a wait to get that pic … looks like rare (for that sub) concrete ties.
Overlooked one more ‘bypass’ obstacle on my last post - the necessary new RR bridge over I-80. Penny here, penny there, pretty soon you’re talkin’ real money [;)] . IMO double tracking wouldn’t be necessary immediately - start by lenghtening every other siding using rail from some of the bypassed ones.
Do the grades over the passes favor directional running on a paired trackage arrangement, so as to cut down on completely double tracking a single route?
