If you look at the the beams that are the top of the Bents they are the same size as the stringers. What size do you think they are? To me they look to be about 6" x 20" , but it’s a guess at best. Is there a standard size for this application? This is a BNSF trestle. Do all railroads use the same size lumber? I model C.P. and might as well get it right the first time. Thanks everyone. [:)]
Brent
As per a Southern Pacific, Common Standard Plan shows stringers being 8" x 18" size. The cap on top of the pilings is 12" x 12". These sizes should reflect most first class railroad trestle construction standards.
If you look closely the cap is actually two beams put together. Here is another view but it doesn’t show much. The cap beams were definitely the same dimension as the stringers.
Brent
There might be something helpful HERE. There are dimensions given on page three of the document and there’s also a discussion of solid stringers versus built-up ones and glue-laminated ones.
Wayne
Looking at the second picture, it appears to me that the caps (made up of two pieces) are roughly square. Looking through Mallery’s “Bridge & Trestle Handbook”, most of the examples are either 10"x12" or 12" square. Thus I would expect the caps to be made up of 6"x12"s. Again from that picture, it appears to me that the height of the stringers is the same (maybe a little taller) as the height of the caps. Thus, if the width of the cap pieces is 6" and, as noted, the stringers are the same width as the cap pieces, the stringers are also 6"x12" (maybe 6"x14").
Now, the ointment on the fly (as we say) is that it is not unreasonable to assume that the originating dimension is 8", rather than 6" (perhaps the builder of the trestle wanted an unusually sturdy trestle). Then the 6"x12"s become 8"x16"s.
To reconcile this 6" vs. 8", I went to the first photo and “scaled” off the picture. I assumed the rails are above the midpoint of each set of stringers. From this I got the stringer width as being 8".
So, there you have it folks. The cap pieces are made from 8"x16" and the stringers are 8"x16" (stringers possibly 8"x18"–see Steamage’s comments). The previous is based on OP’s statement that the stringers and cap pieces are the same width( “The cap beams were definitely the same dimension as the stringers.”).
Ed
CP standard plan B-14-58 for an E-50 trestle, revised to 1968-05-24, shows the caps as 14x14 S2E, which means it is planed on 2 sides so the vertical dimension is actually 13.5". The stringers are 9x18 S2E, and again reduce the vertical dimension to 17.5". But that only has 3 stringers each side.
A recent plan for new construction indicates the only difference is in the number of members. There are 4 stringers under each rail, but still 9"x18" nominal. The cap for each bent remains as 14"x14", with 6 piles instead of 5.
In both cases the bridge ties are 8"x8" on 12" centres.
John
Thanks for the input everyone. It gives me an excuse to make a return trip with a tape measure.[:P] Wayne that was an interesting read and I was intrigued by the use of different dimensions of lumber for the caps on the different bents. Also the use of all the different sized steel plates. along the bridge. I will give it a better look when I’m not surrounded by screaming kids.
I noticed in the photos I posted that the top of the pilings were “squared” off to be even with the caps at the top. Would this be to just keep moisture out? Or is there another reason?
Here is a photo of the walkway. To support the walkway they have used longer ties at the same intervals, except over the Bents. In these spots they have added an extra tie in between the other two. Any ideas as to why? I think it is these little details that can make a model look so much better.[:)]
Brent
I’m a’lookin’ at those extended ties, and I’m not seeing an “extra tie between the other two”. They all look, to me, like simply extended ties. Am I missing something?
Note the cables in this last shot. The upper one is for electrical power, quite probably three phase, what with the three insulated conductors and the bare support cable. Below that is most likely communication cable suspended off a mechanical support cable. Also neat to note are the sheet metal reinforcements on the tie ends. Those could be done with decals, if anyone were to produce them. They’d basically be silver decals with a matrix of black dots. Easy peasy as they say.
These are some neat shot–lotsa detail–thanks for the fun!
Ed
The power and com cables must be to swing this baby.
Brent