After doing extensive maintenance on my trestle, and looking at the condition, I have decided to replace this 12 foot long trestle and bridge with a 7 foot long viaduct with a couple of curved bridges on either end.
Here’s a shot of a train passing over it yesterday.
The problem is that I hand spiked the rail to the ties and EVERY year I have to re-seat the spikes. I just finished putting on a coat of boiled linseed oil on it, to help preserve the wood (cedar), but noticed that the trestle bents are rotting away.
It IS a cool looking trestle, but I want something that doesn’t require as much maintenance.
The first step is to see how straight it is. I put a pressure treated 2 x 6 on top to see how long the viaduct should be.
Now, what would a Viaduct post be withouth the Marx brothers? 
I decided on 7’ for the length of the viaduct; I’ll have an arch cut every foot - so there will be 7 arches total, each half of a 10" diameter circle.
I will use the 2x6 as a platform to lay the track on - just flex track in this case. I’m hoping I can find some AMS tie strips somewhere, so I can use the existing rails.
I am making the sides out of 3/8" Sintec (foamed PVC sheet). They will be 7" high, so I need to cut them to size first. The PVC is 24" x 48" long.
I clamp the 2x6 to the PVC to make a guide for tthe saw and pretty soon I have 4 pieces ready to go.
Eventually, I’d like to use my 2X8 pieces for the curved section to simulate a ballasted through-type plate girder bridge - at least that’s my current thinking.
I was thinking of getting something already made, like these from Split-Jaw, but I’d have to know what radius I need - and I think I already have enough material to make my own.
I thought I was going to do more today, but it’s already 93 degrees out, and OH SO HUMID! Time to come in; maybe I can look for AMS tie strips. 
Next up, I’ll start cutting the arches.
