# MISC | Which type of Tie/Sleeper is best for a Railroad?



## Nexis (Aug 7, 2007)

Recently there have been issues with the Concrete ties in this region , with them cracking and not allowing the water to drain effectively. Is it the fact that the ballast isn't laid properly or the fact that the ties aren't high quality meaning theres flawed contracting. Wooden and Rubber ties haven't had this issue , and some people think its Concrete. I honestly doubt its the concrete , except with the cracking and that in my opinion is due to the bad contracting and quality... Where should concrete ties be used and where shouldn't they be used?


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## Silver Swordsman (Nov 8, 2011)

The reason why "wooden tracks" don't have this kind of problem is because 1) they are replaced much more often than concrete ties are and 2) trains travelling on track using wooden ties go at reduced speeds, which reduce wear on the infrastructure. The only issue that I've read about concrete cracking is from the KTX in Korea, where the construction company given the contract for the trackbed actually had no experience in the field: the rubber pieces holding the track screws in place absorbed rainwater, and when winter set in, froze and expanded, thus cracking the concrete. Speaking of heat expansion, the fact that wood expands much more readily than concrete may be an explanation as to why it doesn't crack as much. 

Water's got nothing to do with cracking concrete: in fact, many high speed systems now use ballastless track in which the track is directly fastened to a concrete bed. I doubt that cold is the direct result of the concrete cracks in your area: the Japanese shinkansen has been using concrete slab track for fifty years without a hitch. Therefore, I agree with you that it was probably poor construction quality instead of the inherent nature of concrete itself: personally, I feel that all ties should be converted to concrete as soon as possible--especially in the US.


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## Suburbanist (Dec 25, 2009)

Balastless tracks are the way to go IMHO. They spread vibration better and although expensive require far less maintenance over time.


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## K_ (Jan 5, 2010)

Silver Swordsman said:


> The only issue that I've read about concrete cracking is from the KTX in Korea, where the construction company given the contract for the trackbed actually had no experience in the field: the rubber pieces holding the track screws in place absorbed rainwater, and when winter set in, froze and expanded, thus cracking the concrete. Speaking of heat expansion, the fact that wood expands much more readily than concrete may be an explanation as to why it doesn't crack as much.


Deutsche Bahn also had problems with concrete Ties on Berlin - Hamburg, but there the cause was a subcontractor using substandard concrete.

Nowadays many railroads go all concrete. Conventional lines use concrete ties, and even the ties underneath switches are concrete. For high speed and tunnel tracks continuous concreted roadbeds are becoming the norm.


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## Silver Swordsman (Nov 8, 2011)

Suburbanist said:


> Balastless tracks are the way to go IMHO. They spread vibration better and although expensive require far less maintenance over time.


I disagree with your claim that ballastless track is better vibration-wise. The thing is, wood absorbs vibrations, making it less loud. When we're using ballastless slab track, not only are the sounds directly reflected and amplified by the concrete, but the very vibrations from the train penetrate deeper into the ground and are felt much more strongly than ordinary tracks. I've stood next to high speed trains travelling at full speed before: the very ground and air trembles.


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## Suburbanist (Dec 25, 2009)

^^ Low-frequency vibrations do, indeed, spread more in concrete than through irregular materials (think of you being in a concrete high-rise and listening some weird vibrations from someone blasting loud speakers beneath you).

However, one should compare trains travelling at similar speeds with similar tracks. Wooden ties would have to be replaced every year or less if they were used for high-speed tracks and it would be more dangerous for the trains in some "tighter" high-speed curves.

That is why they build extensive noise barriers around ballastless tracks, which doubles as safety barriers.

Finally, under high speed traffic, the usual size of ballast rocks is prone to be jettisoned in the air by passing trains. That can harm trains, traffic passing under an overpass, and requires more frequent maintenance.


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## K_ (Jan 5, 2010)

Silver Swordsman said:


> I disagree with your claim that ballastless track is better vibration-wise. The thing is, wood absorbs vibrations, making it less loud. When we're using ballastless slab track, not only are the sounds directly reflected and amplified by the concrete, but the very vibrations from the train penetrate deeper into the ground and are felt much more strongly than ordinary tracks. I've stood next to high speed trains travelling at full speed before: the very ground and air trembles.


On German HSLs they now put sound absorbing material on top ob the slab, between and alongside the tracks. Makes a big difference too.


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## K_ (Jan 5, 2010)

Suburbanist said:


> Finally, under high speed traffic, the usual size of ballast rocks is prone to be jettisoned in the air by passing trains. That can harm trains, traffic passing under an overpass, and requires more frequent maintenance.


Ballast however has the big advantage that it is easy to correct the track geometry afterwards to compensate for terrain movements...


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## Suburbanist (Dec 25, 2009)

K_ said:


> Ballast however has the big advantage that it is easy to correct the track geometry afterwards to compensate for terrain movements...


Indeed. Correcting geometry for ballasless tracks is expensive. But it can be done. They are good for high-trafficked high-speed lines because they greatly increase their reliability without travel speed compromises.


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