N Scale NTRAK Three-Track Stone Arch Bridge – Modular, FDM Printable

A large, three-track stone arch bridge in N scale, designed for NTRAK modules. It has an open-spandrel arch, ornate stone fascia, decorative pylons at the corners and heavy stepped piers. The deck carries all three NTRAK mainlines (red, yellow and blue), and the arch ribs are color-coded to match. It's built in left and right halves sized for normal FDM printers, and a shared pier lets you chain spans into a longer viaduct. Size - Deck: about 352 × 131.5 mm (13.9 × 5.2 in), printed as two 176 mm halves - Piers: 120 mm (4.7 in) tall

What's Included (19 STLs) Deck - Left and right full-width deck halves, each printed flat in one piece - Under-deck cross-seam splice (print 4) to join the halves

Arch Ribs - Red, yellow and blue ribs, left and right of each, one set under each track

Fascia & Pylons - Front and rear arch fascia, left and right halves - Front and rear corner pylons

Piers - Left terminal pier - Right terminal pier - Shared pier, for joining two spans into a longer bridge

Tool - NTRAK track centerline marking jig, for marking the three track centerlines on the deck

Assembly - Join the two deck halves with the four under-deck splices. - Glue the red, yellow and blue ribs under their tracks. - Add the front and rear fascia and the pylons. - Set the bridge on the terminal piers, or use the shared pier to link more spans. - Use the marking jig to lay out your track centerlines before laying track.

Print Settings - Printer: designed for FDM - Layer height: 0.12–0.2 mm. Go finer for the fascia and pylons to bring out the stonework. - Orientation: print the parts as oriented. Deck, ribs, fascia and pylons lie flat, and the piers stand upright. - Supports: minimal. The parts are already laid out to keep them to a minimum. - Infill: 15–20% is plenty. Go a bit higher for the piers and deck, since they carry the trains. - Glue: CA or plastic glue for small joints, epoxy for the deck seam and pier connections

Painting Tip Prime gray, then dry-brush lighter stone tones over the arches and fascia. A dark wash in the stonework and arch recesses adds depth. Add dark streaks from water runoff down the piers, and a bit of green moss near the base. Please post a make if you print it. I'd love to see it on your NTRAK layout!