Sorry Henry - switched gears too fast. (trying to corect the spelling above, then went back to the G/R thing.)
Most of the gauntlet tracks I was around were in dark, low speed territory. Most involved one of the tracks being an old interurban property that somehow survived. The only reason most survived was because of alignment restrictions that would have thrown a switch out on an open deck bridge.
No, mudchicken, you are describing guard rails. A gauntlet track is where two tracks, side by side, cross into each other via frogs so that each track is continuous without switching and the each's track's traffic can flow instead of having to stop for switch and signal however is controlled by a home signal at each end or treated as a block to manage traffic ALSO, like PRR and H&M used at Manhattan Transfer and Conrail and NJT use at some stations, a gauntlet track can be used to keep wider trains or freight trains away from station platforms (usually high platforms) entered and leaving by switches at each end of the gauntlet. Gauntlet was used when two side by side tracks would not work across bridges or through tunnels especially as cars got wider and centers of track had to be further apart. Poughkeepsie Bridge was double track but later gauntlet when wider cars came along then became single track. There are probably hundreds of examples...
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Gauntlet track (glad there is little of that around anymore)
The idea is to keep the wheels on the ties. Just let those wheels dig into the ballast and the railcar gets really unstable. You start seeing splinters and you know that something frequently has an issue.
You will also see single guardrails in certain sharp curves an to protect structural things like piers to overhead buildings. They also appear around switch point derails (alligators), track bumpers and on ocassion, docks.
Yes, two. Only the 'inside' rails cross over each other.
Overmod The disadvantage, other than the obvious, is that it uses multiple crossovers, and hence more wear, shock, and maintenance on bolted track. RME
The disadvantage, other than the obvious, is that it uses multiple crossovers, and hence more wear, shock, and maintenance on bolted track.
RME
Paul of Covington [snipped - PDN] A few things puzzle me about the guard rails in Crandell's picture. The guard rails seem to be considerably farther away from the running rails than is customary. Is there a different philosophy at work here?
The guard rails seem to be considerably farther away from the running rails than is customary.
Is there a different philosophy at work here?
It might be kind of fun to review the standard plans for many railroads, and see what the range of such distances is.
- Paul North.
The rounded ends are transitions, from what would otherwise be a sharp end profile.
The wider spacing is to control an already-derailed car better. Consider the fun if one or more wheels of a derailed truck choose to jump the inside rail on a close-guardrail system (and a derailed 3-piece freight truck is prone to the kind of yaw angle that might produce this). Some railroads think it better to keep the inner flanges within bounds that keep cars from hitting bridge limits, but not precisely in line (or, as previously noted, derailed).
I think the whole question of 'philosophy' comes down more to the preferences of whatever the people, or departments, or railroads which were in charge of that part of the civil decided to use.
As an aside, which verges on being off-topic, having four rails on a bridge isn't necessarily an instance of guardrails -- it might be gantleted track. In some cases where bridges were thought to be too weak for expanding loads -- Starrucca Viaduct being a notorious historical example -- or when two separate railroads shared a common bridge, the lines could be laid 'overlapping' so that two separate trains could not occupy the affected stretch at the same time. The advantage here is that no active switching, and the concomitant risk of problems, is required to implement it. The disadvantage, other than the obvious, is that it uses multiple crossovers, and hence more wear, shock, and maintenance on bolted track.
A few things puzzle me about the guard rails in Crandell's picture.
The rails don't come together at the ends, so don't seem to provide the "funnelling" function to attempt to re-rail or at least control the wayward truck. Also, the ends have rounded noses, as if they were intended to just lift the truck rather than guide it.
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"A stranger's just a friend you ain't met yet." --- Dave Gardner
See these old (100+ years ago !) "P.R.R. STANDARD" plans:
54343 - "GUARD RAIL for BRIDGES, TRESTLES, & VIADUCTS" (see esp. the notes): http://prr.railfan.net/standards/standards.cgi?plan=54343-B&type=COMP
59817 - "NOSE FOR BRIDGE GUARD RAILS" (cast from malleable iron - again, see esp. the notes): http://prr.railfan.net/standards/standards.cgi?plan=59817-A&type=COMP
cx500The wooden 4x8 outside the rails is actually called a tie spacer. On steel bridges it is aligned along the edge of an underlying girder or stringer. Hook bolts, typically every 3rd tie, hook under the flange of the bridge member and keep the ties in line, with lag bolts on the intermediate ties. Today CPR uses a 4"x5/8" steel bar instead for the same purpose. Your CN example, however, seems not to have used this fairly simple system. . . . [snipped - PDN]
Another component that's not visible, though, are wooden spacer blocks (if used). Those are large creosoted blocks just slightly smaller than the timbers, which are placed between the bridge timbers on top of each of the girder or truss top flanges. Then, a group of the bridge timbers are jacked tight against the spacer blocks before the spacer bar is screwed into the bridge timbers from above. Thus, the bridge timbers are held securely in place by the balance of compression from the spacer blocks between them, and tension from the spacer bar above them.
There're many more pieces and details to open-deck bridges than it may seem !
Guard Rail - Usually only set when a cetain span height was reached. (16 Ft on old Santa Fe, per Chief Engineer's instructions)
When you see them come together to make a point/ tip, you are looking at part of a conventional carbon (fabricated railbound rigid) frog being recycled.
Doesn't matter if the bridge deck is open deck or ballast deck. Guard rails function best if they are the same weight of rail or slightly taller/larger.....
The wooden 4x8 outside the rails is actually called a tie spacer. On steel bridges it is aligned along the edge of an underlying girder or stringer. Hook bolts, typically every 3rd tie, hook under the flange of the bridge member and keep the ties in line, with lag bolts on the intermediate ties. Today CPR uses a 4"x5/8" steel bar instead for the same purpose. Your CN example, however, seems not to have used this fairly simple system.
Some roads did consider the wooden tie spacer to be adequate as a guard rail, but inner rails tend to be more effective at guiding a derailed wheelset along the ties until it is off the bridge. A derailment makes a real mess to clean up. If it damages or destroys a bridge the problems and cost increase exponentially.
The inner rails are often called Jordan rails. As you note, there are many variations, especially in the pattern at the ends. Another one I have seen is three parallel rails between the running rails. Possibly a royalty had to be paid to use the Jordan design, and this was a way to evade the fee. The guard rails are usually of lesser weight, but that is because they are usually old rails no longer suitable for normal use, or the running rails have been replaced with heavier sections.
John
selector In fact, at least on the few I have seen in Canada, the practice was to have wooden 4X4 outside the rails mounted on the ties, spiked or bolted in such a way that they formed a retaining rail, except wood. Inside the rails were two steel rails of a lesser weight running the length of the bridge deck and then coming to a styled point about 15 feet onto the ballasted rails, outside the length of the bridge deck. However, those inner guards are fashioned in a variety of configurations. They don't have to come to a point necessarily. This is the CN bridge at Ashcroft, just 4 km east of the town over the South Thompson River, in south-central BC. Not only is there no pointy closing to the guard ends, but the one on the north side is somewhat longer. BTW, this obviously isn't an old timber 'trestle', but is a modern multi-span deck girder. Crandell
In fact, at least on the few I have seen in Canada, the practice was to have wooden 4X4 outside the rails mounted on the ties, spiked or bolted in such a way that they formed a retaining rail, except wood. Inside the rails were two steel rails of a lesser weight running the length of the bridge deck and then coming to a styled point about 15 feet onto the ballasted rails, outside the length of the bridge deck.
However, those inner guards are fashioned in a variety of configurations. They don't have to come to a point necessarily. This is the CN bridge at Ashcroft, just 4 km east of the town over the South Thompson River, in south-central BC. Not only is there no pointy closing to the guard ends, but the one on the north side is somewhat longer. BTW, this obviously isn't an old timber 'trestle', but is a modern multi-span deck girder.
Crandell
tree68 Occasionally on a double track structure you'll see a guard rail only on the "outside" side, instead of the pair one normally sees on a single track.
Occasionally on a double track structure you'll see a guard rail only on the "outside" side, instead of the pair one normally sees on a single track.
Back when I had a model railroad I noticed these inside rails on my trestle and knew they acted as a re-railer. The ones I see on the real thing appeared to be too small to serve that same function. I had wondered about them for many years- glad I finally asked. Thanks, guys!
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CSSHEGEWISCH An interesting variation of guard rails can be found on the CTA, especially on the tight-radius (90-foot) curves. The guard rail along the outside rail is laid sideways almost against the running rail, leaving just enough space for the wheel flange.
An interesting variation of guard rails can be found on the CTA, especially on the tight-radius (90-foot) curves. The guard rail along the outside rail is laid sideways almost against the running rail, leaving just enough space for the wheel flange.
In Traction (which includes both streetcar and elevated/subway) the desire is to have the car pulled around the curve rather than pushed. The main guard rail is placed on the inside of the curve near railtop level and is expected to bear against the back of the flange to prevent the outer flange from contacting the outer rail at all, and possibly climbing over it. This idea also shows up in the "high guard" flanged girder rail used on the inside rail on corners in street trackage. The guard on the outside is less important and is spaced a little farther from the running rail. On some curves, like the former Harrison Curve on the South Side (Green/Orange) line in Chicago, there is a short opposite curve before the main curve, so a continuous guard is used, mostly to simplify maintentance. In the case of a southbound move from Wabash to Holden Court via Harrison Street, the track went left, curved right over 90 degrees, had a short (60') straight section and then turned left a little over 90 degrees. The last curve entered Holden Court without the reverse, a remnant of the switch to the Congress Stub, which was removed in the 1960s.
These rails are called "guard rails" because they are there to guard against a derailed car's getting far from the running rail. You can also find them at switches. There is the story of a new official's commenting on the many short sections of rail that he saw here and there, especially in a yard--he was of the opinion that there would be a great saving if they were removed and put into service as running rails.
Johnny
Supposedly as rerailers or otherwise keep derailed truck from tipping the whole car over. Lots of bridges and trestles have them even today...check MTA elevated lines for instance for distance (had to do it!).
Hopefully to keep the cars from falling off the trestle if some wheels were derailed.
Randy
What purpose is served by the two light rails placed in between the rails on some older trestles?
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