evidently the fill that SP installed to make it a causeway to replace the old tressel is sinkining into the muck of the Salt lake at an uneven rate causing cracks in one culvert and putting another culvert in trouble.
http://www.sltrib.com/sltrib/politics/54989110-90/causeway-lake-salt-corps.html.csp
UP may have to detour through salt lake city and the WP route to Wells? There may be some enviromental issues with the cuseway according to the article.i
When you put fill over waterlogged sediments, they compress, so you have to add more fill as it sinks, which causes more compression of the sediments, and on and on. I wonder if UP has compared the cost to double-track to old WP route south of the lake?
Nothing lasts forever.
Looking at the below link aerial gives one the impression UP has more of a problem that just their track sinking (as the linked news clip mentioned) … Look at the lake color differential on the north!
Years ago everybody and their uncle worked for railroads. But, railroads with so little employees now don’t have the political clout needed to ram things down society’s throat anymore. UP has its hands full on this one.
A most interesting subject and thread! Thanks for starting this thread, blue streak 1.
Best,
K.P.
As I recall from an old National Geographic article, the color differences on either side of the causeway is caused by different algae growth in response to salinity differences fostered by the causeway barrier.
This was completed in 1959. Morrison-Knudsen was the contractor and they moved to Williams, AZ after it was finished and were the contractor for Santa Fe’s the 44 mile Williams-Crookton line change. Most of the same people worked on both projects.
That corrrectly describes a geotechnical ‘no-win’ situation. However, a fairly new technology - which has been used in Salt Lake CIty several times recently - is Expanded Polystyrene (“EPS”) Geofoam in the fills instead of soil, to avoid that compression problem. Notably, that was done in the same or similar sediments - and next to (and to protect) a UP line at that ! A good overview explanation can be found at this article:
A very detailed explanation can be found in this AREMA paper from 2010 (37 pages, approx. 3.0 MB file size):
I remember reading somewhere that when SP was driving pilings for the trestle that used to carry the line over the lake, they broke through some sort of crust, and the pilings literally disappeared. I guess it’s conceivable that a similar barrier may have been breached by portions of the fill.
The last big issue was raising the causeway because of increasing water levels in the lake, which took lots of riprap and a sizeable fleet of old box cars. I, too, wonder how much money is being saved by using this routing over upgrading the old WP around the lake. A shorter route that is slower than the long one can’t cut too many costs.
The paper pointed to by your second link mentioned using hot wire cutters for the foam - at which point I started having flashbacks from Model Railroader articles on using foam and hot wire cutters for making scenery - and putting in fills sounds a lot like making scenery.[;)]
Thanks for posting the links!
PDN; This EPS technique appears to have many applications. Those of us who only dabble in construction can only scrape the surface on the advantages of zero sum excavation used in this construction. I have observed many large buildings that use this method as well.
My only question is what is the expected life of EPS? I woould expect it to be rather long in years ( 100 + ? )
The use of EPS on the lucin cutoff would appear to be difficult due to the EPS floatin
Great Salt Lake is the miniscule remains of Lake Bonneville, a huge lake that 13,000 years ago covered what is now northwestern Utah plus a part of southern Idaho and eastern Nevada. The site of Salt Lake City was completely under water. The gradual erosion of the rock formation in southern Idaho let this lake break loose into what is, by far. the largest fresh water flood in the north American continent. 1150 cubic MILES of water broke loose and eroded the Snake River to its confluence with the Columbia. The Columbia River was backed up by this deluge. To understand this emense amount of water consider that if the entire lower 48 states were completely level the 1150 cubic Miles of water would cover it to a depth of two (2) feet.
Perhaps some of you have been to Register Rock along the Oregon Trail in Idaho. This 50 ton rock was rolled to its present location from what is now Utah. Those who would like more information about Lake Bonneville and this flood may reference the book ROUGH-HEWN LAND by Keith Heyer Meldahl, U of Cal Press, 2011.
Erik - We must have read the same article(s) ! [swg] Amazingly, the same technique is also used to cut out the longitudinal openings for pipes and wires in Structural Insulated Panels (“SIPs” - 2 pieces of Oriented Strand Board with 6 to 12" of foam between them, kind of like a giant ice cream sandwich) as used in building construction - you can even see the inward path of the hot wire towards the circular opening to start the cut !
blue streak 1 - No idea of the service life under those environmental conditions, but I too anticipate it is measured in decades as long as it is protected from mechanical abrasion and solvent attack (aggressive petrochemicals such as gasoline), etc.
This Lucin Cutoff situation is getting close to the “limiting case” for poor soils - so weak in compression and shear that they can’t carry any load for any length of time, kind of like quicksand - or ultimately, like water. I suspect that the worst problem is the static or ‘dead load’ of the fill, which is a relatively large differential even from the adjoining salt-heavy lake water, and which is bearing down on the sediments 24 x 7 x 365 - that’s what’s going to cause the long-term subsidence. In contrast, trains moving over it are heavy and as a ‘live load’ do increase the weight on the sediments, but only for a relatively short time (5 - 10 minutes), and the sediments may not respond that quickly to the temporary increase in load. Even temporary surcharges that are intended to deliberately cause consolidation or settlement are usually placed for time periods that are measured in weeks or months, not minutes.
You’re right, though - floatation of the EPS would be too much of a good thing. So this would be a balancing act, with a very narrow margin for succes
Carl, I do not remember just what year it was, but the rising lake level also precipitated the purchase of several large pumps which moved water from the lake to a dry area on the other side of a ridge–and the pumps have not been used since that year. This water year has been dry, but not dry enough to call for brown lawns. The ski resorts here did have enough snow–and had their first snow, which did not stay, of this season last week.
The article I read in the Tribune mentioned that more fresh water comes into the south side of the lake than into the north side, which causes a great difference in the salinity of the water on the two sides. The trestle allowed much more diffusion than the causeway allows, which, as is noted in one post, causes the difference in color. The brine shrimp that grow in the lake are an export item that are shipped to the Orient to be used as food in fish farms.
Another lakeside industry is mineral extraction.
The Styrofoam shows that we have come full circle, with the prototype following model railroad practices.
The balancing act would be further complicated by the fact that buoyancy would change with seasonal salinity changes, and more importantly, lake level changes. The structure would have to be located away from the present unstable fill. This of course would create another isolated water zone. The structure would need to avoid natural hazards like submarine landslide zones. A partially buoyant structure would probably have to be anchored against wind and seismic induced seiche.
It’s looking like the long term solution would involve the alternate WP route.
“The line proved a difficult challenge, with long tunnels at the Liverpool end and a huge bog to traverse at Chat Moss, not far from Manchester. Stephenson solved the latter problem by using fascines - bundles of wood - to support the rails. Doubters said the plan would never work - but the wooden bundles are still there and still doing their job today.”
If you’re out there on the causeway you can see the color differential as plain as nday. And the stench is indescribable.
One of the issues that UTA and UP have with the foam blocks is that you have to keep the water out of the material. It’s one thing to use it on dry land in the SLC area, quite another out in brackish saltwater.
The stuff on land is protected by multiple thick layers of plastic sheeting or reinforced earth wall sections.
Our AREMA tribe just looked at the stuff under construction in August in the SLC area. It ain’t cheap either.
Interesting article on expanding a floating bridge in Washington.
http://www.wsdot.wa.gov/Projects/SR520Bridge/questions.htm
Robert
The pontoons in the WA bridge were 28 feet high, mostly underwater. Great Salt Lake is very shallow (IIRC about 30’ at deepest along causeway) and its depth fluctuates wildly. Pontoons would alternately be floating and sitting on the variable and unstable bottom, making for a bumpy ride.
Speculating out loud [^o)] , UP has an option that SP and WP never had - bypassing the worst sections of both routes.
It appears that a roughly 26 mile connection could be built between the Lakeside sub (MP 653) and the ex-WP Shafter sub (MP 787). Besides the GSL causeway, the twisty slow grades of the Silver Zone pass would be avoided. The Arnold Loop (40.943812,-114.268545) must be seen to be believed.
Besides the longer mileage there are other consequences. The Shafter sub has mostly tiny (by todays standards) 6000 foot sidings. Also, traffic bound for the UP main drag in Ogden would put more load on the 2MT part of the Lynndyl and Salt Lake subs. Hmmm.