I've seen pictures of a few wooden trestles so far,some of wich being really impressive structures.However,I haven't seen one that featured a double track yet.I'm just curious to know if there were any built that carried two or more tracks,or just as interesting,a gantlet track.
I'm actually planning my next layout and absolutely want a wooden trestle incorporated to it.However,to suit my needs better,a double track set-up would please me but then I don't want an item that would be so far from prototype reality.Not that I count rivets,but still I like to keep some sense in it,let's say "somewhat" prototypical.Thanks.
Hope this helps some, it's sort of an answer but here's what happened:
I was in the process of building an N scale display layout for my store. There were several elements I wanted to incorporate. One was a double track mainline. The other was a curved wooden trestle. While I preach all day long about taking your time with your trackplan, research, don't rush, blah blah blah I ignored my own advice and went full speed ahead until I realized that I'd never recalled seeing a double track wooden trestle.
Like any model train shop, I have many experienced and knowledgeable customers both model railroaders and prototype historians, and when I asked, not one of them had ever seen a double track wooden trestle. Not saying there never was one, just saying in an informal survey of several folks, not one knew of an example.
May not be the most substantial answer, but hope that helps a little.
I agree with OTM (One track mind). I have never seen or heard of a double track wooden trestle bridge. However, watch this space. I am sure someone somewhere will know of one.
I suspect that the reason they are a little like hens' teeth is that railroads who would build a wooden trestle bridge would not run to double track. One pretty simple reason.
The second reason that occurred to me would need some engineering expertise. I suspect that if one was to build a structure from wood that would withstand the loads imposed by double track traffic, then the volume of material needed would make the project uneconomical.
I think that the answers so far are pretty accurate.
I hope that the following helps...
I started my interest in US RR going through journals of the late 1800s (post here can be terribly slow ). I don't recall a single double track trestle including in material about grade seperation. I vaguely recall twin - single track - trestles. I suspect that the point about loadings and stress is the reason for this. Short wooden bridges can be double track.
A large number of wood trestles were originally built (of green timber) to get RR across valleys and land lower than the RR wanted the grade to be at quickly. Later the RR would progressively fill in/around the trestle over a period of time as material became available, traffic allowed and traffic paid for. Put another way... a trestle was a quick solution. When traffic developed it justified bringing fill from some distance to convert the trestle to a fill --- bearing in mind that there might either not be enough fill locally or what was available might not be suitable (sand, loam etc).
(Don't know whether you did it in US... here in UK we often provided materila for fills (embankments) by taking spoil out of local "borrow pits". This left ponds along the line of route. Sometimes large quarries were cut from suitable (relatively close) hillsides. the prefered method was always to balance cuts with fills... sometimes starting cuts from both ends and pushing the material out on both sides to fill the valleys each side of a hill. Sometimes this meant that an obvious location for a tunnel became a huge cut with deep fills each side... I think that in the US you were more inclined to tunnel and bridge).
Further the first line through was frequently a single line. When traffic developed a second line was added for parts of the route first The parts that got doubled (/trebled) were the easy bits that cost less. By the time routes got doubled throughout timber had become more scarce, more steel was more readily available, traffic weight paid for and required upgrading the trestles... AND... the development of earth moving equipment, the desireability of smoother curves and lighter grades for increased line speed... meant that at least additional lines were located differently - sometimes as cut-offs - and frequently not parralel to the original track... so the later bridge would also be single even if it was still a timber trestle...--- which goes to the point that the original trestle would be in traffic while the later facility was built... it would also be kept in use until "life expired" against cost/maintenance --- ... so what you can do is put a wood trestle next to a later steel one... and they don't have to be parralel. ... or you can sepearte the grades and put the later route in a cut, even a tunnel, leading to a short steel bridge while the old route swings out into "space" on a trestle...... the possibilities are numerous.
Two other things that happened... the new route would often be more lightly graded - even when parallel - and, sometimes, the original route would be abandoned... in whole or in part.
A gantlet/gauntlet track is not likely on a long trestle for most of the reasons above. In the early days it usually cost less to put in a switch at each end of a trestle (that already existed) and pay very low wages for the manpower to regulate traffic... asumming that switches weren't sprung or worked by the train crews. A single track trestle would probably not be suitable to convert for gauntlet use... or the cost would be prohibitive... especially given that a gauntlet would creat a bottle neck - the RR would prefer to spend the cash and get the clear thorugh route --- also... you wouldn't want to egt it wrong on a trestle... cornfield meets on the level were bad enough.
I have recently seen pics of a diamond on a trestle...can't recall for sure but the trestle was long and low and I think both routes were single. this raises the point... many trestles were actually pretty low and ran across wet land.
Sorry this is a bit rushed... hope it helps.
While not a tall trestle, the Union Pacific (former SP) line across the Yolo Bypass, west of Sacramento, CA used to be a double track wooden trestle. Go to Google maps, search "West Sacramento, CA" then zoom in on the tracks just north of and parallel to I-80. The UP removed the northerly track but you can see that it is wide enough for the second track on the satellite photo. The beams and many of the bents were replaced by conctete during the last years of the SP.
I tried to sell my two cents worth, but no one would give me a plug nickel for it.
I don't have a leg to stand on.
David is correct. Wooden trestles were often the most expedient way to get a railroad running and generating revenue in fulfillment of contracts and grant conditions from levels of government. For example, in Canada, the Federal Government issued title to huge tracts of land on either side of the rights of way, often 20 miles or more (think about that!). The quid of the pro quo was that the railroads had to be in place before entire provinces withdrew their agreements to join Confederation. My province, BC, was a particular thorn in Sir John A. MacDonald's side. BC squawked so much that McDonald had to agree to contribute money to a railroad running on Vancouver Island which was in place before the rail was completed in the Rockies.
Many of the trestles on the CPR lasted 15 or more years, but they were invariably either filled in or rebuilt in steel once it was determined that they had to be replaced.
I dimly recall a PRR temporary line relocation in New Jersey that included double track decks supported on wooden pilings leading to a temporary deck girder span (or maybe two spans, with a timber piling pier between) over a street. The main overpass bridges were being replaced, so the temporary trackage shifted everything out over the sloping part of the embankment. A parallel street prevented widening the embankment - apparently pilings and a timber deck were less expensive than a retaining wall, considering that the track was only used for a couple of months.
On its outer edge, the temporary trestle might have been as much as 25 feet above the parallel street, but not much, if any, more. If someone is looking for a prototype for a high trestle, this isn't it.
Chuck
tomikawaTT wrote: I dimly recall a PRR temporary line relocation in New Jersey that included double track decks supported on wooden pilings leading to a temporary deck girder span (or maybe two spans, with a timber piling pier between) over a street. The main overpass bridges were being replaced, so the temporary trackage shifted everything out over the sloping part of the embankment. A parallel street prevented widening the embankment - apparently pilings and a timber deck were less expensive than a retaining wall, considering that the track was only used for a couple of months. On its outer edge, the temporary trestle might have been as much as 25 feet above the parallel street, but not much, if any, more. If someone is looking for a prototype for a high trestle, this isn't it. Chuck
This sounds very much like the sort of thing that I've seen in journals from 1890-1910 where RR originally laid down main street (or main street grown up rond the RR) were "grade seperated". As you say the piling as a temporary measure was cheaper than building a retaining wall... also much easier to remove once the new bridge was in. the locals also probably didn't want a huge wall "blighting" their neighbourhood. I would expect that there was a "Slow Order" on that temporary track.
Another solution to this problem would have been to do one track at a time. Older practice would sometimes be to gauntlet the two lines through (on one side of - and then the other) the work area. More recently at Greenwich a short length of line was made single between switches that were remotely controlled... this allowed trains in both directions to use one platform face that was (and is again) a single direction platform.
Plans are available for double track wooden trestles.
Page 71 of Southern Pacific Lines Common Standard Plans, volume 3 (published by Steam Age Equipment Company, PO Box 412 Dunsmuir, CA 96025) has blueprint plans (dated June 1912, revised Oct. 1915) for variations of a double track ballasted deck trestle. It shows variations for a one story trestle, a trestle with more than one story, and a trestle on a curve.
Mark
Wadayuno? According to the SP plans, the outside stringers on the curved trestle are curved. The interior stringers are straight, alternately running the length of two bents.
markpierce wrote: Plans are available for double track wooden trestles. Page 71 of Southern Pacific Lines Common Standard Plans, volume 3 (published by Steam Age Equipment Company, PO Box 412 Dunsmuir, CA 96025) has blueprint plans (dated June 1912, revised Oct. 1915) for variations of a double track ballasted deck trestle. It shows variations for a one story trestle, a trestle with more than one story, and a trestle on a curve. Mark
Mark,
Good work finding those blueprints. Now the big question: did they ever make any bridges off the plans?
I might be reading too much in, but it seems there is a blue print for a double deck, double track trestle bridge. Is that right? Wadda bewdy.
Are there any bridges off the plan? I dunno. But west of Sacramento, CA on the Yolo flood plain there was a double track trestle some several miles long. I don't have information on whether it followed the blueprint. (Was it ballasted or not?) Someone more knowledgeable, hopefully, will read this and clue us in.
markpierce wrote: Are there any bridges off the plan? I dunno. But west of Sacramento, CA on the Yolo flood plain there was a double track trestle some several miles long. I don't have information on whether it followed the blueprint. (Was it ballasted or not?) Someone more knowledgeable, hopefully, will read this and clue us in. Mark It is and was ballasted
Posted previously by me:
"While not a tall trestle, the Union Pacific (former SP) line across the Yolo Bypass, west of Sacramento, CA used to be a double track wooden trestle. Go to Google maps, search "West Sacramento, CA" then zoom in on the tracks just north of and parallel to I-80. The UP removed the northerly track but you can see that it is wide enough for the second track on the satellite photo. The beams and many of the bents were replaced by conctete during the last years of the SP.
Probably not coincidental, the Yolo trestle was built in 1912 and 1913, contemporary with the plan's date.
Dave-the-Train wrote: A gantlet/gauntlet track is not likely on a long trestle for most of the reasons above. In the early days it usually cost less to put in a switch at each end of a trestle (that already existed) and pay very low wages for the manpower to regulate traffic... asumming that switches weren't sprung or worked by the train crews. A single track trestle would probably not be suitable to convert for gauntlet use... or the cost would be prohibitive... especially given that a gauntlet would creat a bottle neck - the RR would prefer to spend the cash and get the clear thorugh route --- also... you wouldn't want to egt it wrong on a trestle... cornfield meets on the level were bad enough.
Not technically double track I know, but as it got mentioned - the Rutland had lengths of gauntlet track on timber trestle between Burlington VT and Rouses Point NY where it "hopped and skipped" across Lake Champlain's island chain. I think the other railroad was the CV (could have been D&H?) but not 100% sure about that.