Plastic ties

[Junctionfan]

I know that instead of wood the rail industry could use concrete and steel ties but what about plastic ties. If you use some sort of dense thermo plastic, it could be very durable and is can be recycled.

Anybody have any information on this idea?

[Big_Boy_4005]

We have recently had a discussion on the use of plastic ties, here's the link:

http://www.trains.com/community/forum/topic.asp?TOPIC_ID=15627

There is a lot of interesting discusion, and I think the answer you seek is there, but buried slightly.

[Junctionfan]

Interesting..thankyou for the link. To change the thread slightly than; where would plastic ties be most useful? I ask because in my area the CN Grimsby Sub is prone to mud and weeds and the wooden ties corrode and breakup within 2 or 3 years it seems.

[Big_Boy_4005]

Wooden ties shouldn't go bad that fast. That would be an indication of extremely poor maintainence. Is the track ballasted? One of the main functions of ballast is to provide drainage so the ties don't rot. Railroad ties are treated with creasote as a preservative. This too should lenghten their servicable lifetime.

Old wooden ties often had date nails in them, telling what year they were made. The nail has a 2 digit number right on it's head. I don't know if this is still common practice, and you may not be able to find them because they are usually on the end of the tie, and aren't exposed, but if you could, it would tell you how long they've been there.

Are they doing any tie replacement along the line? The Union Pacific has has a lot of bad ties along their Altoona Sub. This is the mainline. Those pale blue dots on the side of the rail indicate ties that need to be replaced. The rail was manufactured in 1951, but many if not all of the ties have probably been replaced once since then. You can see that some of the ties are in much better condition than others.

[Anonymous]

Plastic ties have been used in a number of places including the Chicago elevated lines. They are of course significantly more expensive than wood.

LC

[Overmod]

Premise of 'existing' designs of plastic tie is to replace wood ties when existing rail maintenance equipment, personnel, and procedures are used.

The Cedrite-style tie is like 'engineered lumber' in that it uses wood material (chips, flakes, sawdust or whatever is in the proprietary mix) with a binder. It's not 'plastic' in the sense the original question in this thread was asked; it's a composite that derives much of its strength from the fibers and material in the filler. IIRC a major constituent was 'war-weary' tie lumber complete with remnants of creosote preservative... this perhaps being a way to keep the overall 'systems' cost of tie replacement down, on the books, because fewer ties have to be 'disposed of' as potentially hazardous material or dumped at railroad expense...

Other designs of tie use other materials to gain different forms of strength or other properties. Ground-up automobile tire rubber, for example, is a useful filler in a variety of ways, and cannot really be disposed of or recycled in very many other ways. There are social benefits to removing large numbers of dumped tires, particularly in mosquito-breeding weather, which again might abate the overall cost or give useful publicity benefits.

The principal reason not to make 'pure' thermoplastic ties is cost. I have read about various proposals to use recycled, 'post-consumer' plastic (such as terephthalate soda-bottle material or shopping-bag plastic) once the recycling programs have gotten to the sophistication necessary to separate out the types of plastic reliably. Cost of running the recycling programs and transporting the material is extensive. Cost of using 'virgin' plastic suitable for the purpose, even from 'waste' stock (e.g., punchouts or molding gates/sprues) is colossally expensive compared to the cost of concrete ties... or normal wood ties when available. Note that a relatively thin 'skin' and appropriate pockets of high-grade plastic, surrounding a cheaper composite core, are likely to give most of the benefits of an all-plastic tie, and may in fact have better vibration and stress characteristics particularly in colder climates.

When I was looking at designs of plastic tie in the early '80s, it appeared that a 'screw spike' system, similar to that used on some of the ex-EL commuter trackage in northern New Jersey starting in the '50s, would be preferable to spikes; pre-drilling is a bit easier than any kind of preparation effective for traditional spiking, the hold-down and clamping forces are better accommodated with the large 'thread' area, and it's possible to have repeated cycles of loosening and tightening without appreciable damage to the tie material. It does not appear that mainstream approaches have agreed with this: they all seem to concentrate on furnishing a "better wooden tie" that is handled much the same way as a real wood tie would (no pun! No!) be.

Concrete ties can conserve material (since it's understood that a derailment spells replacement regardless of the working cross-section); you may notice that some forms of tie have appreciable 'bevel' in the center at the top; this saves volume of concrete required and saves transportation weight. I have not seen plastic ties manufactured this way, perhaps because their beam stiffness is so much lower than reinforced concrete.

Note that, while fancy Pandrol clips and resilient pads aren't required to give vibration-free service (as they are with concrete), a typical plastic tie requires tie plates (to prevent localized crushing) just the same as a wood tie does. You can mold the plate into the tie... but the cost goes through the roof and not much meaningful effort is saved.

A technical discussion of these synthetic ties in Trains will be much appreciated, including (if any) special ability or disability of these ties to deal with expansion in long welded rail, e.g. in preventing sun-kink effects without resorting to rail anchors etc.

[Junctionfan]

The line is ballasted; I don't know what the heck CN is doing wrong but some of their ties I know have got to have been there since the 60s but some of the ties were replaced a couple of years ago and don't look so good. Their is mud bubbling up from the ballast and CN added more ballast to it and than took the tamper to it.

[Big_Boy_4005]

It almost sounds like some bad soil under the track, below the ballast. Is this in a low lying area with generally bad drainage, or near a body of water? It may be less expensive to keep dumping ballast and replacing ties, than to dig out the area and haul in good fill. If they aren't having derailments there all the time, they are doing enough right.

How busy is this section of track? That's going to be another factor for CN to decide how to deal with the problem. Maybe they are just replacing the ones they didn't replace last time.

[Junctionfan]

The area is in front of a Via station. We see about 16 trains a day of which some are over 150 cars long. The section is in between a railroad crossing and a trestle that goes over a creek and from the crossing and the creek is a declining grade not steap but noticable. The soil has a high concentration of clay in it.

[Big_Boy_4005]

That's actually quite a bit of traffic. It might be too hard to close that down for any length of time, so quick fixes are in order, just to nurse it along.

You may have just said the magic word. CLAY. That type of soil loves to hold water, and when it does, it turns to mush. That may very well be what's oozing up from between the ties. The track may almost be "floating" for a short stretch. I'll bet the trains go pretty slowly through there, and the inspectors are watching closely.

Maybe CN has looked at the idea of plastic ties for this section of track. It makes sense from an engineering and maintenance point of view, but cost wise it may not.

[Junctionfan]

I don't know; there are section of that track that twist and flex. You can imagine how a the trains looks like traveling 50mph on the tracks. Is plain awful and scary considering that if they derail they will crash into a passenger station and will cause alot of people in the residential neighborhoods near by to flee and be evacuated.

It seems to me that if this is going to be a constant safety issue, they should dig out the clay; line the bottom of the roadbed with plastic or concrete and than fill it in with the ballast. I would say the digging would have to go at least 6 feet. As far as traffic, all of their stuff could be routed on CP because most of the stuff is bridge traffic. CN and CP share a corridor route just before Buffalo and the 2 subdivisions merge into a wye. CP runs about 6 to 9 trains a day and tunnels under the Welland Canal.

[Murphy Siding]

     For once, instead of starting a thread, I used the search function to see if there was already a similar thread.  I knew there was a somewhat recent one, but instead,all I could find was this thread.  Sadly, I don't think any of the poster above , post here anymore.

     I'm reading a March, 2003 issue of Trains Magazine that has a short article about UP trying composite ties.  They were to buy 1,000,000 ties for $55 million, over a 4 year period for use in the wet areas of Louisianna and East Texas.  I wonder if anybody knows how they worked out?

[mudchicken]

Cedrite composite ties failed. Can't drop them. Can't put them in tension.

Centerbroke ties were common.

[Murphy Siding]

Cedrite composite ties failed. Can't drop them. Can't put them in tension.

Centerbroke ties were common.

  So a million ties went bad?

[mudchicken]

...a distressingly high number did.  The special handling is also unwanted.

Hint: what survives is mostly in yards. UP never bought the full contracted amount.

[rrnut282]

That was the composite ties.  What about the straight plastic ones made from polyeth (recycled milk jugs).  I would think they would survive rough (normal railroad) handling, except in extreemly cold temps.  I was reading in a RT&S magazine that someone (UP?) was doing some long-term testing.  Anyone (MC) know how that went?

[Anonymous]

I am working on a research project in Quebec that is going to attempt to use hemp with plastics to create an automotive composite that may be able to be used on fascias (bumpers).  This should be able to reduce cost dramatically, provide more strenghth  and be more environmentally friendly.

We are currently looking at other uses for the hemp composite.  Ties may be something that may be feasible. 

Any opinions?

[Murphy Siding]

...a distressingly high number did.  The special handling is also unwanted.

Hint: what survives is mostly in yards. UP never bought the full contracted amount.

If UP didn't buy all of them, I would have to believe they went bad rather quickly.

[mudchicken]

Same problem as Cedrite - They are heavier and they fail in tension.

BNSF had some at Argentine, Northtown, Barstow and and Alliance. I know the cut spikes failed & they were looking at screw fastenings as switch ties and I-Bond ties. Some of the plastic ties initially caught fire with ease as did the flangeway filler material on crossings. 

(ps to another poster - signal department hates concrete ties with a passion.)

[Murphy Siding]

     You know, I'm always amazed when big companies put lots of time and money into R&D on a product, and still produce a dog.  My industry, building materials, is certainly guilty of that a lot.  If I was going to produce railroad ties, that were going to have heavy trains run over them for years and years, I'd keep testing and refining them until they worked.  (Shrugs)  But, that's just me.

[Anonymous]

The quest for new concepts for the production of ties is intriguing, but coming up with a new process using virgin material that can compete with the cost and durability of concrete or timber is probably all but impossible.  However, it does appear as though there is quite a bit of activity pursuing the recycled plastic composite ties.  Getting rid of a waste material by casting it into dense masses that can fill the endless demand in the huge market for railroad ties seems like a real win-win proposition.  But I would think there would be a devil in the details.  There must be hundreds of variations in combinations of used plastic, tensile reinforcement fibers, bonding materials, and processes that might lead to the most ideal result.  But with such a huge potential payoff, it really seems like fertile ground for the inventors. 

Natural fibers such as hemp as mentioned above by SURF-PREP might indeed be viable as tensile members cast into polyethylene ties.  Square stem rosin weed (Silphium Perfoliatum) also has strong fibers in big stems.  I can imagine these low cost natural fibers being wound into rope or cords of maybe 1/8" diameter and composing a quite dense matrix where they are less than 1/16" apart with the poly filling around them.  These fiber bundles would run the length of the tie just stopping short of the ends.  So there would be probably as much fiber as there would be plastic in each tie.  The plastic would be injection molded under high pressure, so it might be possible to completely penetrate the cords and encapsulate each fiber.  If the fibers were neutralized from any natural decaying chemicals that they possess, the plastic might be a perfect protection from any moisture that could threaten their longevity.  Waterproofing is one of the virtues of plastic.  I would think that using recycled plastic and hemp reinforcement to produce ties would result in ties that could truly be called "green," as in in as "going green."