Making Bridge Approach Trestles
With our Howe truss bridge starting to come together, not only did we need a way to keep it up off the bench, we needed a way to support it and the track to and through it. Part of that equation is the stringers to support the track that rest on the bridge beams and trestle bent caps. The other part is the approach trestles that support the ends of the bridge itself.
The design of the approach trestles was more of an afterthought than an actual planned ahead design. While the stringers can rest directly on top of the trestle bent caps, the bridge itself must sit lower than that to account for the thickness of the truss bottom members plus the crossbeam thickness, basically at least an inch lower. Add the thickness of the "shoes" that rest on that bent and it already has to be more than an inch shorter than the rest.
The bents we already have are all the 20" tall ones, a scale 40' tall. We'll need to make more, or cut down and refit some of the ones we already have. It ends up being a little of both. Because we'd already assembled three bents into an approach trestle already, the idea is to "tack" on another shorter bent, attached to the taller one. This way the bridge can rest on the shorter one while the track stringer and rest on the bent caps and bridge support members.
Attention shifts to making the actual track stringers and bridge tie "strips". I have to admit, I got caught up in the "exact replica" modelling mindset. So much so I designed a "slide tray" for the table saw to dado the tie strips to fit the ties! Even the track stringers are assembled in staggered fashion like the prototype. It's a lot of work and painstaking attention to detail in return for prototypical authenticity. And I built a LOT of them.
Cranking out piece after piece, they came together into a very realistic looking trestle... That never got used. To add insult to injury, the dogs trampled it to pieces while it got moved here and there and everywhere until it was finally in so many pieces the only thing that made sense was to dismantle it and store the bents and other parts until once again needed.
All that being said, at least the approach trestles were used and the Howe truss bridge was the centerpiece of the layout for years. Eventually the dogs found a way to keep knocking them out from under the bridge and slowly beat them and the bridge to pieces. Each repair used thicker, sturdier pieces of stock, but over time they could not stand up to the constant pounding.
