Trestle Part 3: Bridge piers

Progress continues on building the new trestle for the PE&A.I measured the length of the trestle and estimated I would need around 24 bents. So I made nine additional bents this weekend to add to the 15 I put together last weekend. I also spent some time ripping a whole bunch of 1/4" boards that I'll need to assemble the trestle. It is my least favorite task not only because it is so tedious, but because it requires a face mask, eye protection and ear protection. It's noisy and hot and stuffy, so I only want to do it on cool, rainy days. Fortunately that describes what Saturday was like.

I also put together two more panels for the retaining wall which leads up to the low point of the trestle. Depending on how the weather, next weekend I expect to install the retaining walls and the build the south trestle between the retaining wall and the bridge.

Nine new bents.

A big pile of 1/4" boards and a huge cloud of dust.

I'll be extending the stone retaining wall by two feet in order to replace these bricks.

I made the two one-foot wood frames for the retaining wall to accommodate the curve of the track here. Rather than using vertical supports like I did last time, I decided it would be easier if I used horizontal supports made from treated 2x2 pieces I had leftover from another project. The offset of the far left support will make sense during installation.

As I did before, I applied tile to the tops and entire sides of the wood frames. I will treat them this week so they'll be ready to install by the weekend.

And the final thing I did this weekend on the PE&A was build the bridge piers. When a wooden trestle includes a steel girder bridge span, there are typically two or more bents at each end, supporting both the bridge and the stringers that connect it to the next bent. Here are couple of photos of prototypes I found on the internet (example one, example two) that I used to help model my piers. I decided to use three bents for each pier, two of which will support the bridge, and third will be part of the trestle.

First I determined the height for each pier, 9 1/2" for the south pier and 12" for the north pier.

I also had to determine if I needed to offset the tops of the bents. My bridge is 3/4" thick, which by coincidence is exactly the same size as the wood I'm going to use for my stringers. Therefore all three bents would be exactly the same height. 

I marked the height on three bents and then cut off the extra length. I decided to switch to hand tools for this rather than using a table saw.

I then added bottom sills (also known as mud sills) and two more cross beams. These are for the 12" north pier.

Next I bundled them together using small bungee cords, then attached sills and cross boards on the sides.

Here in the north pier in place. You can't tell from this photo but the pier is resting on a brick as a foundation. I plan on placing each bent on a brick foundation rather than letting it rest directly on the soil.

And here is a photo showing the bridge with both piers in place at the end of the day.