For regular wood rail road ties, the (sorry if this is the wrong term) “spike plate” has an option for multiple spikes. I have noticed that usually on straigtaways, only two spikes are used per plate, but around curves or in switches, multiple spikes are used. The reason for this appears to be obvious.
However, for cement ties, there is no option for multiple tie-downs for the rail head. Is this because the “tie downs” (I don’t know what the heck they are called) are so much stronger than spikes that there is no need for added strength?
Gabe: I am so glad you are bringing up concrete ties! They are installing some near our watch site, so will be interested in anything that is posted about them!
…My observation on stated question might be to the fact the spikes work loose in wood ties and so often are raised up an inch or so while the connectors on concrete ties seem to have a more positive connection and are up to the task at hand since it appears they are most always tight in place.
Concrete ties generally have a cast steel locating device cast in place into the concrete (I don’t know if it is attached to the reinforcing rods). One of these steel castings sits either side of the rail.
The rail usually sits on a rubber or plastic pad, and held in place by a spring clip, the most common being called a “Pandrol” clip. This is located in a hole through the steel locating pin parallel to the rail, and the rest of the clip is a curve turning through a bit more than a full circle with a curved section contacting the rail.
The clip is driven into the locating hole with a sledgehammer, compressing the curved section as a spring so that it holds the rail down with considerable force. When properly applied, the force is enough to restrain the rail from expanding and contracting. This effect is assisted by the weight of the concrete tie and the fact that the ballast has been packed around the tie by tamping machines.
So, yes, the force applied by these spring clips is much greater than that of conventional spikes which really only locate the rail in gauge and do not restrain it longitudinally (rail anchor clips fixed under the foot of the rail against wooden ties are used for this with conventional spikes).
Incidentally, the gauge is usually wider in curves, by up to 1/4" to allow freer running and to reduce rail and flange wear, so special concrete ties need to be used in curves.
M636 is pretty much on the money…The same holds true for D-E/McKay clips as well. The adze pad underneath mitigates the abrasion on the concrete surface.
How well the pandrol fastener is fixed to the prestressed steel is a question of the manufacturer’s quality process and where the tie goes.
Just for your information, they are called concrete ties, not cement ties. Cement is the bonding agent in concrete. Concrete is the final product of mixing stones, sand, water, cement and sometimes various chemicals to change the properties of regular concrete. Steel rebar (rods) are usually casted into concrete forms (or railroad ties in this case) to provide extra strength to concrete.
You must be looking at a very light-duty branch line or industrial spur if there are only two spikes per plate on tangent track.
Pandrol is a brand name; generic name is e-clip. There are lots of knock-off Pandrol clips on the market from places like India. You have to check the metallurgy very carefully before you buy. They’ll hold once, but if you knock them off for a rail transposition and put them back, they may not hold twice.
I cringe when I hear “cement” when “concrete” is discussed, e.g., cement sidewalk, cement mixer truck, cement building. Cement is a powder, comes in a bag or a P-D trailer or covered hopper. The instant water is added it’s concrete. Also annoying is tarmac (as in airports). Oh well.
Related to concrete ties in curves - I must have witnessed one of the first uses of concrete ties in switches back in 2002 or 2003 when I commuted regularly to my then workplace in the north of the Netherlands. I noticed they were proliferating but only recently was I struck by the fact that concrete ties are now also frequently used with double slip switches here in the Netherlands. Utrecht Central Station is one place where you can see a good many. The ties used for the switches are noticibly larger in size than those used out on the mainline but regular concrete ties seem to be getting bigger as well.
Are concrete ties being used on switches in North America?
Conrete switch ties are in use in the US, but they require special handling which will keep them from being very common. Hardwood ties or Azobe are much more forgiving in so many ways.
Azobe = super dense/ heavy African hardwood. So dense you cannot drive a spike into it & never needs treating. (Bugs, water and rot avoid the stuff - destroys regular drill bits)
Why over “here”?..I’m over “there” with the Kalmbach gang, LC and grandpa JayE (who must have been borrowing your net)[^]