John,
Thanks for your explanation.
I see no reason to suspect that the “snakehead” phenomena referred to in early accounts is unfounded or even rare. My interpretation of it is as follows:
It occurred with strap iron rails, which I conclude were wrought iron bars approximately 3/8”-3/4” thick, and 2”-3” wide. They constituted a hard rail-like running surface, but unlike conventional “T” rails, strap rails had insufficient beam strength to carry the load across the gaps between ties. So, the straps were supported by longitudinal timber stringers running parallel beneath them. I assume that the straps had holes through which they were nailed to the timber stringers. Since the straps were supported by the timber stringers, there was no need to attach the straps to each other at their ends as is the case with “T” rails.
However, this butt joint between straps would be a bit weaker in weight bearing capability compared to the rest of the strap, as is the case with “T” rails that are joined with joint bars. So, the strap rails would tend to crush down into the timber stringer a bit more at the joints than along the rest of the strap. Once that began, the wheels would add impact as they left one strap in the dip and slapped onto the end of the next strap as they rose out of the dip. Considering that the wheel would slap the next strap slightly past the end of that strap, it would tend to cold-form the iron downward at that point, and thus cause the very end of the strap to begin to curl upward as a response. So, over time, the wheels would cold-work the iron, causing the ends to curl upward higher and higher. The development of that curl would further add to the impact that was forming it.
When the end of the curl became high enough, an approaching wheel would try to go under it rather that rising up to going over it. When that happened, the strap had no choice but to be torn off by the under-wedging wheel.
Here is one that I found in the railroad accident accounts from the Railroad Gazette:
"February 1894
25th, on the Columbia Branch of the southwestern of Georgia, near Ducker, Ga., the engine of a freight train was derailed and overturned by striking a “snake head.” It appears that on this part of the road the old fashioned track, consisting of light rails fastened to longitudinal wooden stringers, is still in use."
Here is another historical reference to snakeheads:
[
atsf.railfan.net]
I conclude that the term, “snakehead” refers generally to all occurrences of a rail being lifted and torn loose by a wheel no matter whether it is strap rail, “T” rail or some other version of rail. I do not know whether such a lifted and torn off rail would need to penetrate the car bottom in order to qualify as a snakehead. Many, no doubt failed to penetrate the car bottom. And not every one that did penetrate the car bottom would have caused death or injury. So there certainly could have been some exaggeration of the hazard.
