What are the advantages and disadvantages of cement and wood sleepers?

Question

What are the advantages and disadvantages of cement and wood sleepers?

Answer 1

The concrete ones are a lot heavier and have a corrugated bottom so they resist moving better, especially in curves.

They have very little flexibility so they need to be very well ballasted in order to not crack. Once in and installed properly they can last almost indefinitly, the devices that fasten the rail down never work loose or back out so the rail is held down much more securely than with wooden ties.

However, they are indeed more expensive but it has been deemed to be a worthwhile tradeoff.

Wooden ties are usually placed at average 18" center to center and concrete ties are placed 22" to 24" center to center so there are a few less ties needed per mile of track, resulting in savings of ties and associated fastening hardware which can be quite expensive.  

For less heavily used track and track that is not maintained to as high of standards wooden ties are still better.

If a peice of equipment drags over a concrete tie, for instance one derailed wheel, all the ties will break in a short time.

Our company did not have much luck with the composite ties, they were made of recycled ground up ties mixed with a plastic resin.They are so much harder than wood that the ballast did not bite in and they slid sideways horribly in curves, they had to put every other one as a conventional wood tie to hold the track alignment.

In addition the composite were so hard that normal tie spikers would not work and they had to be predrilled. I imagine there will be more development in this area, for instance corrugated bottoms as they do with concrete.

Answer 2

I did see something from the FRA at work though about concrete ties wearing out under the rail and causing amtrak to derail in Washington state.  It was on the BN and there was reports of the concrete ties were worn down 1 1/16" to a 1 1/2" causing the rail to spread out and produced wide gage on a curve. so I don't think that they are meant to last forever.  but can be betting then wood.

Answer 3

Concrete ties have one major disadvantage when compared to wooden cross ties (sleepers).

Many times, a derailment produces only one pair of wheels or one truck "on the ground".  Where wooden ties are employed, often times the derailed equipment will continue to roll, while cutting or otherwise damaging wooden ties.  This can lead to the trouble being discovered either by observation or electronic track side detectors before the derailment becomes serious and the cars scatter all over the place.

Not so with concrete ties.  If a wheel or truck derails, the concrete ties basically explode, and everything is all over h**l and back, as in right now...

Answer 4

Well, wooden ties are more flexible under a heavy load and are not as prone to cracking or breaking as concrete ties.  However, concrete ties can withstand heavier loads and have a much longer lifespan than wooden ties (which generally last about 50 years), and I believe they are a bit more expensive than wooden ties.  In any event, here in the U.S. most of the major private Class I railroads are switching more and more to concrete ties on their high-speed main line routes so I suppose they have found concrete ties to be more advantageous than wooden ties.

Also, composite ties, which are essentially made of a plastic compound, are also gaining favor for their flexibility and the fact that they can be recycled for reuse, something that is quite environmentally friendly.

Answer 5

cement sleepers are harder than wood sleepers.