… but were afraid to ask. 
This is interesting stuff, at least for a geek like me. 
Be sure to watch the video, “Legacy.”
Concrete ties aren’t new, inspite of the article they were tried in 1911.
The standard Railroad of the world… tried concrete and steel…
Wasn’t to be … yet. Oh it was the Pennsy.
John
I mentioned the steel ties the Pennsy tried also.
In case all y’all were curious…
John
I just don’t really see how steel ties would work. Many railroad signal systems place a voltage on one rail, and when it senses that voltage coming back to it on the other rail, it knows the block is occupied. Some systems are sophisticated enough, that they can reasonably deduce how far down the block the train is, by the variation in voltage between the 2 rails. That system would not work with steel ties.
I also have question about concrete ties. Concrete is very strong, but somewhat brittle. It doesn’t like to be flexed over and over again. That usually causes the concrete to crack. I have watched the ties on the local railroad move up and down with each passing axle, sometimes they move several inches. I am sure the even though the whole tie moves, there has to be some flexing to the tie.
Concrete is strong in compression, weak in tension. Tension would be a flexing type motion.
Lou, that is why the steel reinforcing bars are usually heaviest on the tension side of the bending equation.
Yeah, concrete ties never made much sense to me, it seems like they couldn’t possibly last very long before cracking from repeated flexing.
On the other hand, now that I think about it, concrete bridges flex all the time too yet they hold up ok.
I read that whole thing and now I am a well-informed tie-kind-of-guy.
And look at the concrete bridges the RR’s build these days - cast on location. Watched CSX build over the Escambia River in Florida a few (?) years back after the hurricane took out the I-10 bridge and old RR trestle.
Ray Dunakin said:
Yeah, concrete ties never made much sense to me, it seems like they couldn’t possibly last very long before cracking from repeated flexing.
On the other hand, now that I think about it, concrete bridges flex all the time too yet they hold up ok.
Not the one on the Parkway East here in Pittsburgh. They actually built a bridge like structure underneath of it, to catch all of the falling bits, so passing cars don’t get damaged.
Concrete ties (sleepers over here) are very common on UK railways. Of course, as many will know, we fix the rail differently.
Alan, isn’t there lighter axle loading over there, as well?
Steve Featherkile said:
Alan, isn’t there lighter axle loading over there, as well?
Given the monsters that have and presently operate on American railroads I guess you are right, Steve. However, in the embryonic days of railroading I think it was more equal.
I blame Vanderbildt, Harriman and Hill for it all. (plus others I guess (http://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-surprised.gif))
Nice reference Steve. The “Tie Guide” really pings the geek meter for me, great stuff:
http://www.rta.org/assets/docs/tieguide%20revised%209%2005.pdf
[edit: not sure why this link isn’t working, but copy-paste the entire line into the url box and it should be ok]
Cliff Jennings said:
Nice reference Steve. The “Tie Guide” really pings the geek meter for me, great stuff:
http://www.rta.org/assets/docs/tieguide%20revised%209%2005.pdf
[edit: not sure why this link isn’t working, but copy-paste the entire line into the url box and it should be ok]
Cliff there are spaces in your addy, %20 is byte talk for ’ ', not every program likes that symbol… or gaps. Delete %20 (3 times), use hyphens or underlines for gaps/spaces.
John