I have planned on installing a trestle bridge here from the drafting stage as it makes for a great focus piece right after you enter the railroad room. It spans the valley, crosses the western lead of Rock Valley and connects the eastern mountain range with the western on the branch line.
Once the bridge is assembled from templates taken from the layout to ensure a proper fit and radius, it is set in place using guide blocks on either end as shown below. This makes sure the bridge is positioned at the correct height to the rail will all line up properly.
Once properly positioned I use scrap pieces of wood and place them under each bent. I then use wood shims to wedge the scrap wood and bridge into place for plastering. Note that I lightly glued the concrete foundation to the bridge. Once I have the foundations plastered in place, I carefully use a utility blade and separate the foundations from the rest of the bridge.
This enables me to be able to easily remove the bridge for when I do scenery and will ensure that the bridge fits back in the exact proper spot. A few spikes and two rail wires and the bridge is completely free.
As you can see below, removing the bridge will give a lot more room to work on the inner parts of the layout without damaging the bridge.
The rails are spiked in place right above the bents. I do not have the guard rails installed yet. I will install them once I have finished doing the scenery in this area and when I am sure I will not need to remove the bridge again.
The inaugural run over the trestle that will function trouble free for years to come. Once the scenery in this area is complete it will look even better.