The reason for my question is this. I recently purchased a trestle from someone who built it and then decided he didn’t want to use it on his layout. So it was well worth the $50 in my opinion. I am building a new pike, which will have several bridges and particularly two trestles.
I got this thing home and it just doesn’t look right. I placed and N scale engine on it and it look more “in gage” or to scale then when I put an HO engine on it. The HO engine has no room on either side of the bridge ties no catwalks safety rails or fire barrels. So I open the box for my existing trestle kit a JV Models curved trestle and the bridge ties are exactly the same length and size? So were trestle build to any standard or were they just individually designed the way that particular engineer (not the guy who drives the train) wanted it to be? This is bugging me to the pint where I think I need to modify the bridge a little and install cat walks etc. But even the trestle bents look more engage witht he N scale unit. I’m crazy enough I don’t need anything else to add to my insanity …lol
Think the way the railroad thought… You start with the existing terrain, and you build your grade around it, over it or through it depending on the local situation. A small wood trestle would not likely have a walkway along the side, that would add to the cost. Typically a wood trestle was the cheapest way to get from point A to point B, so it wouldn’t have a lot of jewelry, and be sized to meet the local conditions.
Fire barrels would be a requirement though, especially in steam days. You can add longer ties and some bracing underneath to extend a platform away from the track.
Not all trestles had walkways or fire barrels. I wouldn’t even say half did. Especially by the 50’s or later.
Yes, there are engineering standards for the load the trestle is designed to carry. Within a railroad there are standards on how that railroad builds its bridges. But there are no fixed standards for bridge design that all railroads adhere to.
It depends on what the bridge was designed to carry and whether it was designed to have a walkway. There is NO requirement a bridge have a walkway. Many do not.
It may be your bridge is designed using narrow gauge plans or for a very light loading, then you are trying to put larger standard gauge cars and engines on it. It may be a bridge designed for 4-4-0’s and 30 ton cars and you are trying to SD70’s and 100 ton cars on it. The size of the bents and their spacing will be look “wrong”.
Some states have (or have had) single-side walkway requirements and other states have (or have had) both-side walkway requirements. Some states have no requirements for walkways. We design all new bridges with both-side walkways but of course the overwhelming majority of bridges are not newly constructed and may not have walkways.
AREMA publishes bridge standards but there is no requirement for individual railways to adhere to them. The AREMA standards are usually exceeded to some extent by each railway. BNSF and UP have moved toward a common bridge standard for simple bridges.
Another thought - many trestles were designed and erected as a quick and dirty way to get the line open, then filled in (with a culvert at the bottom) when traffic warranted and finances permitted. If you pull up a satellite view of Edgemont, SD, and follow the old rail line (now a trail, and very visible) east from the wye at the north end of town you will come to a humongous fill across a rather deep valley. It was originally a trestle, not very heavily built, which was filled in when the line was upgraded to accept 2-6-6-2 Mallets.
You might consider installing your trestle with some obviously-new piles of dumped fill around the bents at one end, to model a similar situation. That, plus a slow order, is what the C&NW did east of Edgemont.
And I’ll bet you didn’t realize that C&NW owned Mallets.
Well let me clarify a few things, this by scale isn’t a monster of a trestle but it’s not one that spans a small creek or gullies either. I have a few Campbell kit bridges that cover that. It is approximately 261 feet long so I would say it somewhat of a medium sized trestle. I see your point about it possibly being intended for narrow gage but when I compare it to the JV Models bridge which clearly indicates it a large trestle the timbers and such seem to be the same size. I did read the instructions on the JV kit and they provide fire barrels and a handrail and catwalk.
I understand the engineering load carrying standards and all that but I guess it just comes down to the eye. If it doesn’t look right then it isn’t. I recently had the pleasure of seeing Howard Zane’s Piermont layout in person. Awesome doesn’t begin to describe it. On his layout he has numerous bridges. I would venture to say every type of bridge is represented. Viaducts, timber trestles, stone bridges, steel stone etc. All of them look perfect not even a hint of a question as to weather or not the scale is correct or does it look right.
That’s what I am attempting to achieve on my layout. It has to work it all has to look right. Achieving the level of craftsmanship of the Piermont may be far greater then my modeling skills but it won’t be for lack of doing things the correct way.
I seem to recall reading somewhere that within (about) twenty years of May 10, 1869 the Onion Specific had filled in all of their trestles. Somewhere I remember encountering a photograph of a 4-4-0 and a string of side-discharge gons atop a trestle engaged in dumping fill for this very purpose.
As a footnote, a lot of 'box" tunnels run through filled trestles.
I doubt that all the trestles were filled in that way. After all the main purpose of a trestle is to bridge a waterway, drainage course or some other transportation means. If you fill in the trestle you have to build something to carry the water or road or railroad. Many rivers were too large to put in a culvert so they had to keep trestles.
One of the most common pictures from the UP on “filling in a trestle” is during the construction of the Lane cutoff (Omaha to Fremont), they built the fill by building a trestle and then filling it in. But the trestle was only used during construction and wasn’t used as an actual bridge. And not all of that was filled. There were at least 3 locations that were retained as bridges (now steel trestles and truss bridges). Originally all the roads passed through “tunnels” built in the base of the fill. The last of them (132nd St) was daylighted and turned into a bridge back in the late 80’s.
The CPR originally built wooden trestles, dozens of them, in the Rockies, Selkirks and Coast ranges to comply with their contract to complete a transcontinental railroad so that the Convservative Government under Sir John A. MacDonald could comply with its own bargain to get British Columbia to sign on to Confederation. Those trestles were built in the early-mid 1860’s. Within 20 years, most of them had been replaced with steel girder and truss bridges, many of them superb and spectacular.
On the other hand, I walked over three substantial wooden trestles on the north shore of Cameron Lake west of Parksville on Vancouver Island three summers ago. They were used until the mid-90’s to service the pulp mill in Port Alberni. They are probably the second generation of wooden trestles there since the line is many decades old.
To our OP, do you have calipers? Measure the timbers and see what they scale out to be. Anything near or thicker than 12" is going to be fine if you convert your measurements to HO scale. A trestle deck varied over roads, but the ties typically were about 10’ long, often 12’ when a walkway and safety station were present.
Well I did just that the other night. I measured the bridge at several point and compared the measurements to the JV Modles kit as well as a Campbell kit and it is HO scale. However it jsut doesn’t look right the bents look too lightweight it you will and all the measurements in the world don’t mean squat if it doesn’t look right. One of the best model railroaders told me it has to look like it belongs there it has to look in scale even if it really isn’t. After all this is for the most part a visual medium. I have yet to see a micromoter, scale or pair of calipers set on a layout. I’ve elcted to place this trestle on a back section of the layout where it is not as noticable or may even scrap it all together.
A year or so ago I volunteered to help with some trestle restoration work for the National Park Service. The trestle that is being rebuilt was built to SP standards around 1923. The bridge ties were 8X8 on top of beams that are 12 X 18 that span 15 feet between piling bents. The Piles vary in size but at the top are 14 to 18 in diameter. The cross beams across the piling bents also vary but are at least 12X12. Cross bracing is 6 X 8. The ends of the bridge ties are spanned by 6X6’s that run parallel to the beams. (note - all dimensions are nominal and in inches).
I agree in principle that you must satisfy yourself when in this hobby. If you first purpose to please others, you are in for a very rough slide. Accordingly, if your mind’s eye says the dimensional lumber is too slight, then change it. Please yourself so that you can enjoy your work.
The Pennsylvania RR had Standard Plans for 4, 5 & 6 post timber trestle bridges, none of which incorporated walkways or platforms for fire barrels. Jeff Scherb’s book, Trackside on the Pennsylvania, Vol. 1, includes scale drawings of all three types redrawn from original PRR plans. There is also a version of this book available on CD which includes PDF versions of his CAD drawings that can be printed out in any scale the user chooses.