Yesterday afternoon I took photos of the laying of a third track at Crystal City, VA. After they dug down deep and rolled the earth with a steam roller, I was amazed that they put down rubber pond liner. Then, they covered with crusher fines (crusher fines are used for laying sewer pipes and as ballast for garden railroaders). If there were any stones in the crusher fines, which are a quarter inch or less in size, the workers manually removed the rocks. (ballast will undoubtedly go over this).
My guess is that the crushers act as a cushion so the pond liner won’t get punctured. At the end of the rubber is the roll, awaiting to be unrolled some more.
My other guess is that the pond liner serves as a weed barrier and also serves to prevent the crusher fines and ballast from disappearing into the clay earth.
Then, along came one of those ugly CONRAIL diesels, looking like it just got out of the paint shop.
Incidentally, the worker with the pole basically stands around for hours chatting with his helper, enjoying the nice spring weather. I think the pole does some sort of elevation measuring.
I don’t think they were using “pond liner” but rather a “neopreme membrain”. Actually they are very, very close to the same thing. The use is most likely to prevent water perculation. If the wqater table is hign in that area (i.e. dig down about 2 or 3 feet and hit water.) The membrain is used to keep the water from “working up” into the top layers of the roadbed. The pond liner that is available here in sunny sandy eggo has a “top side” that is a special layer to inhibit growth of moss etc. Other than that “top coat” the main difference between liner and membrqain is that membrain is about two to thrree tims as thick, and much more durable. Membrain MUST be covered as (in most cases) it is not UV resistant, where pond liner is.
For the average guy standing more than three feet away is not going to see the difference.
Dave thanks for the photos and the posting. Always edjamacational to see how the 1:1 boys do it; and amazing that, for whatever reason, it sure looks very similar to the process used by a lot of garden railroaders. [;)]
I spoke with some other rail fans and they tell me that the liner might be used as well to contain spills. The crusher fines could also absorb whatever spilled (oil, radioactive waste, etc).
YES, this track is near the Potomac in the 100 yr floodplain. A Cat 3 or 4 hurricane direct strike would do it.
Yes just did and replied, sorry! “Check Email” was on the to do list under wax the car when it gets nice out lol its been a while im bad about checking [xx(]
found this online thought it might help shed light on the subject… du ponts research
High speed railway trains place great demands upon track foundations; heavy shock loads that are intensified by even the slightest irregularity in the rails. Conventional support for railroad trackage throughout the world is coarsely crushed, dense rock and this is the material used by the Japanese National Railways for some 12,000 miles of operating lines. Unfortunately, even this heavy ballast loses its effectiveness when laid over subsoils that are quickly turned to mud by rain or subterranian water. The pounding of passing trains pumps this mud up through the space between the ballast and it is washed away, undermining the foundation for that section of track. In 1973, after intial laboratory work, three groups of experiments were begun at selected sites on tests to strengthen subgrade by chemical treatment, tests of plastic and elastomeric sheets material placed between the subgrade and ballast, accelerated physical testing of the sheet material with a vibrator. It was concluded that a physical moisture barrier was required. For this purpose, plastic sheeting apperared to be less serviceable than elastomer selected, on the basis of accelerated testing plus in situ performance was Neoprene.
If you look closer you will see both cabs are empty and there are 3 guys standing there, it’s called a break, the 3rd guy is operating the other front loader on the high side! Talk about ball busting, can’t contrators take breaks?? sheesh! and that guy with the rod, has perhaps the most important job out of the 3, if he’s wrong with the grades, thats some serious $$$ wasted!
Whell at least they have learned a thing or two from back in the day. Never try to run tracks threw the middle of a swamp, but Np had to have there way. Its olny a three percent grade down and back up in about half a mile. Fun to run threw though.
