Strap rail was generally rolled with a defined head and a toe along one side of the rail, through which the spike holes were drilled. Drilling a hole in the head of the rail would severly weaken the structure of the rail, but some roads chose to attach the rail that way. Steel rail didn't come about until well after the American Civil War. If I have time, I will post a photograph of an authenticated piece of iron strap rail later with the spike holes offset.
In the case of the cast iron rails, they were probably cast to one standard radius and then laid to that radius - and no other.
The WWI trench railroads had a similar situation. They used pre-fabricated rail sections, straight and in one standard radius. The things looked rather like pre-WWII American Flyer tinplate track, including five steel trough-section ties per length.
Chuck.
As others have said, I think strap rail could be curved without any trouble. You could nail it down to the wooden basework, and then simply drag the basework into a curve just as is sometimes done with modern “T”-rail track after the rails are spiked to the ties. For especially sharp curves, I assume they could have rolled the straps into a curved configuration.
The question of making curved track seems more apparent with the cast iron fish belly rails shown in this book starting on page 657. I don’t see how you could curve these. They could be cast as curved sections, but that would require a separate pattern for each degree of curve. I doubt that they could be formed to a curve after casting straight. They are relatively short, and set on stone piers. I assume that they were laid as straight rails forming straight facets of a curve, which was probably okay for slow speed tramways:
http://books.google.com/books?id=mJZVD-c73_UC&pg=PA664&lpg=PA664&dq=railroad+strap+rail&source=bl&ots=_x3qVmONq-&sig=zEuzLulI-JkMh0u09PPUAuLFKs8&hl=en&sa=X&ei=3FcGVMDAENLJgwSY6IK4Cw&ved=0CFUQ6AEwCQ#v=onepage&q=railroad%20strap%20rail&f=false
Making curves with strap rail was really pretty easy. The straps were drilled or punched every few feet for a flathead fastener (I assume a nail, but I suppose a screw is plausible). Lay down the strap, set the first two fasteners, then the second fastener becomes a bend point. Tug, fasten, tug the next segment....
One of the reasons strap rails failed so often is the pounding they took in the area where the fasteners were placed.
Getting back to forming curves with strap rail.
Steam-bending timber for ship frames was a mature technology by the time the strap-rail builders rolled into town. - and most early railroads started at ports, most of which probably had active shipyards. The curves required for ship frames were a good bit sharper than anything a rail car would be happy on.
I doubt that the shipwrights would have looked at the rails as competition. After all, if the railroad started bringing more stuff to the port, then more ships would be needed to take it away...
Chuck
There is quite a bit of information in this book, although it appears to be all text. But quite detailed nevertheless:
http://books.google.com/books?id=STMY_aXMcZcC&pg=PA598&lpg=PA598&dq=strap+rail+on+curves&source=bl&ots=4z1zukk3hb&sig=P34UZAgxFgAYLZGfWpPT5dQExv8&hl=en&sa=X&ei=5Q4NVNvlKNGwyATYw4KQCQ&ved=0CEMQ6AEwBw#v=onepage&q=strap%20rail%20on%20curves&f=false
Part of the problem seams to be that unlike early British railroads, early American railroads were pitifully inadequate when it came to documenting there development. Most of what we know comes from the few line's that did keep some records and from manufacturer documentation. Also a lot of early records simply didn't survive, some of the documentation we do have was from later historical research done in the mid-19th century on. The book linked above is just about the only concentrated source of early American railroad construction I've seen. Most early RR books are almost entirely British in origin, but strap rail was something purely American.
Have fun with your trains
This is a pretty interesting topic. On account of my readings of railroad history I certainly know what strap rail is, but I've NEVER seen any answers or possible answers to the original posters questions anywhere.
Even now all we have are some pretty good guesses from other posters. Maybe at this late date no-one knows. We'll probably have to wait for a railroad builders handbook from the 1830's to surface somewhere.
I'll be looking.
Euclid Here is an interesting book on the development of railroad track. The amount of design variety is astounding. Toward the end, it shows some old frogs: http://books.google.com/books?id=mJZVD-c73_UC&pg=PA664&lpg=PA664&dq=railroad+strap+rail&source=bl&ots=_x3qVmONq-&sig=zEuzLulI-JkMh0u09PPUAuLFKs8&hl=en&sa=X&ei=3FcGVMDAENLJgwSY6IK4Cw&ved=0CFUQ6AEwCQ#v=onepage&q=railroad%20strap%20rail&f=false
Here is an interesting book on the development of railroad track. The amount of design variety is astounding. Toward the end, it shows some old frogs:
As near as I can tell, based on the old single rail turnout in that old book, it seams like they must have just kinked the angle of the strap track every so many yards until they got something resembling a curve. Must have made for a really jolting ride.
One wouldn't think that 140 pound rail (140# per yard), or the Pennsy's 155 pound rail would be flexible, and in short lengths, it's not - I know of at least one culvert that uses rail laid side-by-side for it's "roof."
But beyond a certain point, it's pretty "loose."
I have no reason to believe that strap rail would not have similar flexibility, although the possibility of it deforming on curves (cut a strip of paper and try to curve it flat on a table to see what I'm referring to) would certainly be a concern. But as has been mentioned, speeds were much lower in those days, so the "corrugation" that would result would be of little consequence.
Sometimes small lines dispensed with the strap altogether, running on the bare wood. Such was the case of the "first" Fulton Chain Railroad in the Adirondacks, with ran from 1888 to 1892 on simple wood rails. It was only eight miles, and ran pretty much exclusively in the summer.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
I don’t know how they laid strap on curves, but they may have just bent it around like they bend rail today. Straps have flexibility even in the “hard way” direction of bend. Regarding the dreadful “snake heads,” the rolling action of wheels running on strap rail would tend to roll-form the strap, causing it to curl and lift up at the ends. Wheels would push the curl down until it got a little too high. Then a wheel would suddenly dive under the raised, curled end of strap, and violently wedge it upward and through the wooden car floor.
1. Not sure, but I suspect that it was small straight pieces. Remember, trains were not traveling very quickly at this time period, and strap rail was a carryover from the horse-powered days.
2. Stub switches, with a similar mechanism to today's.
3. Not very stable at all! But trains were short, relatively light, and slow.
In a television production several years ago called "All Aboard" they talk about how hazardous strap rail was because it had a tendency to come loose from its mooring, spring up through the floor of a passenger car, and spear passengers.
Solid cast iron, and later steel rail, eliminated that hazard.
They don't mention or show how curves were formed, but turnouts in those days were stub end points instead of the tapered points used today.
There was a question about the strap rail example on display at the Rochelle Crossing park picnic area, solid iron "strap" rail head nailed to solid wooden beam rails under, and that got me to thinking about how practical this system was in application compared to solid iron rails, so a couple questions that pop into mind:
1: How did they produce curved rails? Making a strap rail straight was a no-brainer, but how did they make curves? Particularly in yards where tight curved were a must. Did they make composite wooden beam rails? Just use shorter section to create the curve with a continuous curved strap above? If so how did they keep these smaller sections from pulling a part, was there a strap joiner at the side of each wood beam change in arc connection?
2: How did they build turnouts? Similar concerns as #1, I'm pretty sure they were all stub switches but I have never seen anything showing just how the actual mechanism was achieved.
3: How stable was all this? Namely how much was warping an issue with the wood underlayment? Seams like in the extreme exposed conditions most wooden strap rail systems while cheap to build, would have been maintenance nightmare requiring constant vigil and repair/replacement. The then not uncommon "Snakehead" where the strap rail broke loose getting caught on a wheel and tearing up into a car would to me be more due to the wooden component becoming weakened by exposure giving the bolts/spikes not enough friction to hold the strap down under a heavy train.
Not surprising that most RRs switched to solid iron rails as soon as they could afford to, except in the south where weather wasn't as extreme as up north and labor costs were extremely low, they lasted there until the Civil War.
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