Moving onward and a couple of observations/changes along the way.
The original 60' was right at the limits of the printer bed and created a bit of a bevel to the ends of the side plates, not quite sure why though as I thought the LED display on these modern printers was pretty much vertical across the whole bed. Anyway the bevel was toward the inside so the outer edges actually but up really tight, it's a good thing to have but it shouldn't be there. I also couldn't get the full five section concrete unit in, again odd as it's the same length as the side plates. Rather than fight it I decided to just go smaller.
To that end I've opted to drop down to 50' and get a complete five section concrete sub structure in one hit, I did reduce the sections from 12' long to 10' long to even them out. I also added a single doubler plate to the base flange, it's barely noticeable but it is noticeable if you get my drift.
I've also worked up the water pier unit and the land side buttress, but forgot to add the bearing pads on that module. At this point the second observation came around, 3D printing is totally the wrong medium for objects like this, however it is fast and near instant results....faster than scratch building from other materials.
From the side it's fairly obvious how much better the combined concrete section deck is.
I've only printed three water piers for four spans, and there again was another observation, even in Ho it takes up quite a lot of real estate. The second 50' span is in the printer, another observation, with zero failures so far it's still chewing through a lot of resin, what you're saving in time you're paying for in materials.
Inside there's no cross bracing or attempt to clean up the support side of the beams, you can barely see under here so why bother. What I did do though was to design in some slots, so that if the beams do begin to warp I can solder up 1 mm bar section to make cross braces; these'll drop in the T slots and hold the two sides the same distance apart. Or, just bend some 1 mm wire to fit in one leg of the T slot and then cross to the other side and do likewise. You'll have to excuse the white stains, it's dried IPA after cleaning from rubbing down.
The piers are designed as two parts, the water pier and the upper retaining 'plug-tower', it has a slot in the top to grab the ends of the concrete deck and with corresponding holes, accept the 2 mm bracing rod. So far there hasn't been any tendency for the middle to warp, bow or sag so the 2 mm bar may not be necessary through the full length.
I'm also dubious that it'd have any effect at countering and warping forces if I'm honest. I will however still use it to pass through the two deck sections and tower plug to bind them all together and line everything up.
The idea of the separate towers is two fold, it makes it smaller to print (much faster) and will allow the piers to be set into the layout and then the whole bridge lifted out to add the scenery and water. The towers drop into a well in the pier and there's three holes in the bottom, for one good reason.
I use Devcon 5 minute epoxy and it's quite thick, quite often with blind holes the adhesive will form a good seal around the two parts and create a bubble at the base, or worse yet, squish the adhesive out and all around your nicely detailed and painted pier and bearing pads. The holes should allow excess adhesive and any trapped air free passage out of the cavity and ensure the tower drops in nice an level.
The separate parts also allow me to simply change the pier on another bridge if I choose to and not have the added expense of different towers etc.
The final shot is toy train play mode, the view you'd see if you were at water level as the train passes, the type of bridge and pier is aimed more at a water level route like Columbia River as opposed to something in the Cascades or Feather River, however, just by changing the pier you can opt for either type of scenery though from what I have seen, the mountain routes tend to almost certainly favour wooden decks; probably as they're easier to fit and shift the raw materials into poor access locations.
I've not yet decided on the play set scenery as yet, two track roundy roundy might loose it's appeal as will endless industrial shunting, so something that mixes both, but not a massive township, just something very local and scenic.