While in Altoona, PA last weekend, I saw an NS work train unloading brand new wood ties along the ex-Pennsy mainline. I also noticed a fair amounted of ties marked fro replacement. It’s good to see NS taking care of the line, but I have to wonder why they went for wooden ties instead of concrete. I would think the longer service life of concrete ties would justify their higher up-front cost.
This is only a guess, but they wouldn’t use concrete unless every crosstie was being replaced. For spot replacements of wood, they would use wood because the two types can’t be easily intermixed.
…And I’m guessing, for that area…wood does just fine. No use to change over.
It is a climate issue really. Concrete would not benefit because of the heavy freights and the climate in the Northeast, with the exception of the Northeast Corridor because of the lighter Amtrak trains.
You can have heavy freight, you can have a crappy climate, but you can’t have both. At least that is what I was told.
This is only a guess, but they wouldn’t use concrete unless every crosstie was being replaced. For spot replacements of wood, they would use wood because the two types can’t be easily intermixed.
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Your dead on. Concrete ties are only really useful for the heaviest of traffic, and are only good with other concrete ties.
Here on the Old SF Transcon in Streator Main one was Relaid with Concrete Main 2 with Wood. I asked a couple MOW employees why they go as a Test to see which way they will go when they redo the tracks in 5 years. The test segment is about 100 foot long Tangent and carries about 50 trains a day so they want to see which one will work the best here. From what the MOW boys tell me concrete might be coming to the old Transcon all the way to KC.
It’s been my impression from previous discussions here that concrete ties are definitely better (manufacturing issues notwithstanding), at least until a wheel hits them - as in during a derailment.
That solidity that works to advantage in normal use becomes a liability when the tie suffers an impact. Wooden ties have a certain resilience. Concrete ties crack. Thus if a wheel runs down a stretch of wooden ties, they can probably be reused, as long as they can hold spikes. If a wheel runs down some concrete ties, they’ll probably all have to be replaced.
The immediate cost of replacement wood ties are cheaper, but not necessarily in the long run. A study by CSX showed that concrete ties can get on average 40 years of use versus 8 to 25 years for wood ties, depending on climate.
In an article by John Banchardt he writes that the swing to concrete is becomming the thing as enviromental concerns are an issue and he adds staying green with gas emission is also advantageous when using concrete.
Commuter rail has made the change but he predicts that weight heavy freight routes may see the change to concrete ties and mentioned stimulus money may provide some funding.
OK I’ll bite: What special provisions on the trackiwork are needed when transioning from a section of concrete to wood ties?
In the western U.S., concrete ties are generally less expensive delivered to the site than wood ties. In the eastern U.S., wood ties are generally less expensive delivered to the site than concrete ties. This is a result of shipment costs, energy costs, and raw materials costs.
Installation of concrete ties requires different equipment and skills than wood ties. Maintenance of track laid with concrete ties requires different equipment and skills than wood ties. A railroad cannot justify investment in the additional eqiupment and skills for concrete ties than it already has for wood ties unless it perceives it will engage in a large, long-term concrete tie program. Because of the initial cost differential for ties depending upon which region a railroad happens to be in, the equipment and skill costs raise the economic threshold even higher.
There are several broad cases for tie material decisions, each of which have different criteria:
- The high gross-tonnage Class 1 freight railroad case favors concrete tie in very high gross tonnage territory and heavy curve, moderate-to-heavy gross tonnage territory – if and only if the life-cycle cost is lower than wood tie. In the western U.S., usually it is. In the eastern U.S., usually it isn’t.
- The high-speed passenger rail case, e.g., the North-East Corridor and the various new-build projects, favors concrete tie because (1) it wants to minimize time the track is out-of-service for maintenance and concrete tie has a longer replacement cycle; (2) it needs to a
There is only one actual scientific study done to date that compares greenhouse gas, life-cyle costs of wood vs. concrete ties, which was done in Australia. It found that concrete ties might have lower emissions, under certain conditions which pack in a lot of assumptions that might not be true. Moreover, that study is specific to Australian climate, forestry practices, rail tonnage, rail maintenance practices, energy costs, energy generation practices, materials costs, and so forth. Its results cannot be extrapolated to any other location on Planet Earth. Our review of the study found that it’s useles for informing U.S. decisions.
RWM
You were told wrong. Ask your source how he/she explains the widespread, long-term, highly successful employment of concrete ties on CPR, CN, BNSF and UP in much more severe northern climates than the Northeast Corridor.
Concrete ties are used on the NEC to improve ability to hold track geometry, reduce train delays necessitated by maintenance activities for tie replacement and track lining and surfacing, and improve ride quality. The NEC also hosts 286K axle loads of freight trains, by the way.
RWM
None. You just can’t mix them up in anything less than solid segments, which is what Tony is saying. Concrete ties are on different spacing than wood ties, so the tamping equipment that is set up and designed for one does not work on the other. Concrete ties require different ballast tamping than wood ties, different ballast, different fasteners, and so forth. Mixing them up can be done if you don’t mind de-mechanizing your track maintenance and running up your costs to stratsopheric heights. It’s very common for railroads to swap back and forth from concrete to wood over bridges, through grade-crossings, through turnouts, and through special trackwork. What you don’t do is go XXYXYXXYXYX. You go XXXXXXYYYYYYXXXXXX.
RWM
KCS used concrete ties on its Rosenberg-Victoria stretch (old “Macaroni Line”). The climate is hot and humid, subtropical, and I guess that is a more cost-effective choice than wood since they laid completely new track over the 100 mile distance.
(1) Most of the railroad was already gone on the Macaroni Line.
(2) KCS went bananas on rebuilding the subgrade with geotextiles and asphalt (not always successfully) and had a chance to beef-up a horse and fresno built roadbed with current technology and materials.
If I’m the local roadmaster and I know I have recurring subgrade issues and ballast pockets, I don’t want those concrete ties on my road. If I don’t have the equipment to maintain those concrete ties and a commitment from above to help maintain the plant, I don’t want to see those concrete ties either. Most yards, with rail less than 115# won’t see concrete ties ever and most older yard geometries won’t accept concrete ties, especially around turnouts.
It generally is not as simple as switching wood to concrete. Lots of seemingly innoculus factors come into play.
Fasteners I have seen and understand. Can you explain different ballast, different tamping, spacing and so forth? Are concrete ties a less depth than wood? Any information appreciated. I have observed most concrete ties have a dip between rails instead of straight across.
Concrete ties are a hard ride. I hope they never show up around here.
FWIW, the concrete tied CSX around here averages several mainline derailments a year compared to our wood tied zero.
John Galt is a fellow who painted his name on overpass pillars and aprons from the east coast to the far midwest some 40+ yrs. ago. He was quite handy with a brush and a spray can. If one sees a new signature today, it is his grand son probably. He traveled the National Trail ( I 40). When we were trucking , his signs broke up the boredom aside from the extreme intrest of a traffic situation. I wonder if a face was ever found for the name.
By different ballast, RWM means different ballast x-section. Wood ties absorb some impact loading, Concrete Ties just pass on the blow to the next medium (the ballast) and then the sub-ballast and then the subgrade. More ballast needed to cushion and distribute the load. Concrete ties have a much stiffer track modulus than wood, so the spacing gets increased dependent on the rail section.
As for the dip in the concrete ties, that section had no structural reason in tension or compression to be there and just added weight - so it was done away with.
I will have to ask him again, he’s a track foreman on the Pittsburgh Line, and he told we with the combination of th climate, the type of soil that covers Pennsylvania (and much of northeast), and the constant heavy freights, concrete ties are just not suitable on the Pittsburgh Line.
Note: that the Northeast corridor does not see as much freight traffic and does require a smoother ride, but it’s primary purpose is the service of lighter passenger trains and not constant heavy freight.