Is there such a thing as perfect ballast material?
Only if it is harder than diamonds, cheap, local, drains really well, incredibly angular and repels mud & dirt.
Everybody tries to make do with whatever is available at a reasonable cost. (and then you get some goofball that can’t understand why gravel is a bozo no-no [banghead])
Gravel, like in river rock gravel, the smooth, round stuff?
Every day, I watch a trainload of pinl quartzite head south from Dell Rapids, S.D. to Sioux City, Iowa. I presure that a lot of that is being used for ballast. Yet, a lot of the tracks around here are ballasted with granite from Minnesota.
Does ballast wear out ?
Ballast does wear out. Mechanical action turns it to dust.Some faster than others (like steel mill slag)…usually it fouls before it degrades.
River rock ballast is too soft, degrades too fast, never locks up (insufficient fractured sides, no friction to speak of) and is like putting ball bearings under the track.
Who would knowingly make a decision to bllast a line with something that won’t hold up? Or ballast that’s just not up to the task?
Plenty of people, usually driven by the “culture of cheap”. Plus the arrogant and the ignorant. Happens enough that railroads and folks like PDN & I are wary of it.
Well, there was a time when the budget and the task just didn’t meet up, not even close, and it was neither arrogant nor ignorant to find a good pit, process the gravel for tangent track, and get the company down the road 5 or 10 years hoping for better times.
These may be good times by comparison, but they may not be permanently so either and it would be a waste of useful and sometimes painful experience to forget not how it was done, but how it had to be done to keep the railroad moving.
Quite a topic for thoise of us not ‘in’ the business! A rock, is a rock, is a rock,is a rock, NOT!
Like Wal-Mart; Cheap is not always a good deal over time. This is a pretty intense study of how useful a rock might be in specific circumstances: For those who are interested this link may be of some use:
http://www.minsocam.org/MSA/collectors_corner/article/mohs.htm
“MOHS’ SCALE OF HARDNESS”
“…Mohs’ hardness is a measure of the relative hardness and resistance to scratching between minerals. Other hardness scales rely on the ability to create an indentation into the tested mineral (such as the Rockwell, Vickers, and Brinell hardness - these are used mainly to determine hardness in metals and metal alloys)…”
Not only railroads are interested in rocks usefulness, but highway departments as well. States mandate hardness of rocks used in their highway bridge construction, as well. Often times traveling large distances to find specific qualities of hard rock for special uses, ie;hard surfacing of a bridge deck. And railroads as Mudchicken mentioned want a hard rock for ballast with angular surfaces to promote drainage.
One of the best sources of ballast around in the east is the big (and I do mean big – miles long) “trap” quarry just east of Westfield, Massachusetts on the old B&A (now CSX) main line. It has a direct rail loadout (not accessible to the general public). Very similar is the big quarry in North Branford, CT, which even has its own rail line to a barge facility on Long Island Sound. There are also quarries in New Jersey, and a very large one near Sault Ste. Marie in Ontario…
Trap is a local term for diabase, an igneous rock of basaltic composition which cooled quickly (relatively speaking!). Very very fine grain, weathers slowly, crushes into wonderful angular fragments, extremely hard as rocks go. Great stuff.
“Moh’s Scale of Hardness” is a start, but the principal laboratory test that is used to qualify - and more importantly, disqualify - ballast materials from the standpoint of abrasion and other break-down type degradation, is the Los Angeles Rattler Test. The typical cut-off point is 40 % loss of weight of the large pieces to fines or dust, etc. I believe the protocol for that test is that it is done with the ballast stone dry - though much worse results can occur when the rock is kept wet.
But the best real test is observation of in-service performance under heavy traffic over several years, esp. in the wetter northern climates with frequent freeze-thaw cycles in winter. That doesn’t lend itself to easy quantification in objective terms, but anyone with track experience who monitors it will know it when they see it.
Steel slag has a further problem as ballast when used in signaled territory…it still has some metallic content…metallic content that will conduct electricity and in damp/wet conditions give false track occupancy indications and all other forms of unintended signal actions.
Just as an observation, apparently gravel wasn’t so bad to use as ballast, say, 65 years ago. Here’s how 1792.1 miles of Pere Marquette main and branch line shaped up in 1944:
Stone: 276.0 (15.4%)
Slag: 12.9 ( 0.7%)
Cinder: 142.6 ( 8.0%)
Washed gravel: 536.0 (29.9%)
Pit gravel: 632.9 (35.3%)
Sand: 191.7 (10.7%)
Admittedly, most of the sand ballast (can we translate that as “no ballast”?) was on branch lines. Gravel still made up the majority of ballast on first and second main track (almost four times as much gravel ballast as stone ballast). On branch lines, nearly a third of the trackage was ballasted with sand, just under half with gravel
What is often referred to as “gravel” or “pit,” is in fact “processed” gravel, which is pit run gravel washed and run through crushers to produce clean, fractured rock and in fact has its own AREMA classification. “Processed” gravel from a good pit (high quartz/granite/feldspar) is heads and shoulders above “gravel” but unfortunately, is/was not often clearly i
In addition to the ballast’s composition, size is important, well, for the ground pounders at least. In areas, where with heavy foot traffic, a finer grade of stone, called walking ballast, is preferred.
Nick
There seem to be many people who will use products that are not suitable because the boss, owner, etc does not know that garbage is being used and the aforementioned person gets credit for doing the job for less money and may well be gone when the real bill comes due.
Murphy Siding:
Who would knowingly make a decision to bllast a line with something that won’t hold up? Or ballast that’s just not up to the task?
When you decide how to meet a given budget that comes from “up on high,” and its not perfect and doesn’t come close to it, and you also need to keep the railroad running, let me know what you would do, “knowingly.”
One word: Quartzite. This rock is composed of high grade pure silica sandstone that has been metamorphosed under extreme heat and pressure to a partially melted state and then cooled.
Quartzite is almost pure quartz (SiO2, Silicon dioxide), a very hard mineral, very resistant to chemical weathering, and almost totally insoluble in water. The rock scores high on the Los Angeles Rattler test for mechanical degradation, and the breakdown products (silica particles) are non-cementing (unlike limestone, for example).
Unfortunately, I don’t think quartzite formations are all that widespread throughout the US. The most notable is the Baraboo Quartzite strata in southern Wisconsin. The CNW’s quarry at Rock Springs, Wisc. (west of Baraboo) supplied much of their ballast from the late 1950s on, and the UP is still using ballast from there.
There is another formation (or possibly the same one) of quartzite under part of southwestern Minnesota and eastern South Dakota. Some of the rock surfaces at Redwood Falls, Minn., and another outcrop is the “Red Rock Ridge” which runs east-west about 50 miles due west of Mankato. There is a quarry on the east side of the Minnesota river at New Ulm (the North Western retained a short portion of the original Winona & St. Peter main line to serve this quarry, complete with an ancient swing bridge). Other quarries (both very active) are at Sioux Falls (Concrete Materials/Sweetman Construction, originally CNW served), and Dell Rapids, SD (L. G. Everist, ex-MILW line, now Dakota & Iowa).
By the way, quartzite’s characteristic pinkish and purplish coloring is caused by iron oxides carried by water through the original sandstone. This was an interesting tidbit learned on a University of Minnesota geology field trip to Baraboo (in November!) many years ago. I still have my rock specimens from the trip.
Trap rock (mentioned by other posters) is good also. I don’t know how it compares on the LA Rattler test; would be interesting to find out
Good overview, Kurt - thanks for the time it took to write that up. [tup] I’ll see if I can find some values for the LA Rattler test for traprock.
A small addition: Around here were have several varieties of limestone with differeing characteristics. One of them - dolomite, which has a lot of magnesium instead of one of the calcium atoms, as I understand it - is considerably harder, and is also beloved by the cement mills because of the wonderful cement it makes.
- Paul North.
Is good ballast worth recycling, if a line is pulled up?
‘It depends’ - but yes, it can be, mainly as long as it doesn’t have to go too far/ incur too much trucking or hauling costs to the point of re-use. I’ve done it several times.
More commonly, though, a line that’s being pulled up is having that happen because there wasn’t enough traffic - hence it probably didn’t have any good ballast applied over its lifetime anyway. Then, too, even the best ballast can be ruined by having mud and debris - such as coal dust/ dirt - foul it, and/ or mud ‘pumping’ up into it from underneath. So this is rare - it probably happens most often when a main line is abandoned, which is thankfully rare, or relocated. If the relocation is in conjunction with a government project of some kind - like a new road or dam/ reservoir project - the agency usually claims the ballast.
A few months ago we had a thread here about a fellow in Ohio or Indiana who bought a lengthy abandoned CSX line, mainly to salvage the ballast for his construction business, but also to sell off the R-O-W to the adjoining land owners. That’s a more common fate for the ballast, rather than ralroad re-use.
- Paul North.