Bachmann On30 Porter 0-4-0s can negotiate a 12″ minimum radius and Nick wants a large trestle.

I had an idea but was having a hard time describing it to Nick so I made a quick planning model in 1/8″ = 1″ scale. The footprint is 30″ x 4 feet long and about 4 feet tall.

I made a pencil sketch to show how the bridge would look.

The lower back will have room for a separate small town/logging camp area. We may do this in HO scale.

We labeled lots of the construction dimensions on the planning model so it’s acting as kind of a 3D blueprint.

The frame is made of 3/8″ x 4″ plywood planks ripped on the table saw and connected with 2×2 blocks glued and screwed. We added casters so it is easy to roll around.

Next we built up the sides and made an oval of plywood as the roadway.

We’ll cut away the portion that will be spanned by the bridge.

When you say “micro,” how micro do you really mean?

We want to run trains round-and-round so we need a loop. The size of a small layout is dominated by its turn radius. The size of the turns will be decided by the size of the motive power. I have a bunch of Bachmann Porter 0-4-0s in On30 around so we’ll use these to rule the design.

I love the Internet. A quick Google of “minimum radius porter 0-4-0” returned a link to a pdf:

On30 Commercial Loco and Car Minimum Radius Guide written by the infamous “Professor Klyzlr” [BTW, Professor Klyzlr, I would link into your site but it has no home page.]

And the data the Internet On30 community has given is that Bachmann says 18″ radius but people find that 12″ is a practical minimum and 6″ is absolute minimum. I’m going to shoot for 10″ radius — but I’m going to test that.