Tunnel portal, vaulted, double-track – opening to the standard, with and without overhead line, N, TT, H0

Description

The opening follows the formulas for tunnel profiles, so every vehicle that meets the standard passes through on both tracks, with a margin above the clearance. The portal has a face of neutral stone masonry with an arch ring and a short piece of lining behind it; you build the hill around it.

• Opening by formula: width and height from track gauge and clearance, open-line track spacing; straight track.
• Without and with overhead line: the second file is taller (lowest contact wire plus allowance).
• Face of neutral stone masonry with an arch ring, printed flat with the face down, no supports; no lettering, not a replica of a particular structure.

In the set per scale:

• N: crown 42.2 mm above rail top (with overhead line 44.9 mm), width at rail-top level 54.5 mm, track spacing 25 mm
• TT: crown 56.6 mm above rail top (with overhead line 60.2 mm), width at rail-top level 73.4 mm, track spacing 34 mm
• H0: crown 76.5 mm above rail top (with overhead line 81.5 mm), width at rail-top level 97.9 mm, track spacing 46 mm
• Per scale one portal without and one with overhead line.

Scales: One variant per scale: N (1:160), TT (1:120) and H0 (1:87). There is no Z (24 mm opening, details too fine for FDM). Each variant contains the single parts and a collection plate with all parts of the scale (3 mm apart).

Dimensions: Dimensions taken from NEM 105 (2013 edition), NEM 102 (2019 edition) and NEM 112 (2024 edition). The numbers are calculated from the formulas of the tunnel sheet with the clearance values of the 2019 edition; the factors in the sheet are approximate. The height counts from the foot of the portal = rail top: if your track sits higher than the baseboard, shim the portal by that height, otherwise it is missing at the top. In curves the opening needs more width; this portal is not calculated for that. Wall thickness, face width and joint pattern are a free choice. How accurate it turns out depends on your printer, and our part has not been tested on a layout yet. Print the free check gauge first to see in advance whether clearance and distances suit your setup.

Material: PLA is enough because the layout stays indoors; PETG works too. 0.4 mm nozzle, ideally 0.12 mm layers, no supports.

Not a toy. Model-making accessory for model railway hobbyists aged 14 and up; contains small parts that can be swallowed, keep out of reach of small children.

Dimensions

Dimensions of the default variant in print orientation.

Material and temperature

PLA is enough for gauges and structural parts (0.4 mm nozzle). For small details use resin or a 0.2 mm nozzle. With resin: wear gloves, follow the resin manufacturer's instructions and cure the parts fully.

Print orientation: Face down.

Safety notice

Not a toy. Model-making accessory for model railway hobbyists aged 14 and up; contains small parts that can be swallowed, keep out of reach of small children. Not a toy. Model-making accessory for model railway hobbyists aged 14 and up; contains small parts that can be swallowed, keep out of reach of small children.

Not an original part. No affiliation with the manufacturers named; brand and model names only indicate fitment.

What's included

You get one ZIP for the version you choose, with:

• STL – print-ready mesh
• 3MF – with print profile
• STEP – editable in CAD

Files per version

Version	Contains	Price
N (1:160)	tunnelportal-gewoelbe-zweigleisig_n_sammelplatte.stl, tunnelportal-gewoelbe-zweigleisig_n_sammelplatte.3mf, tunnelportal-gewoelbe-zweigleisig_n_sammelplatte.step, tunnelportal-gewoelbe-zweigleisig_n_portal_ohne_oberleitung.stl, tunnelportal-gewoelbe-zweigleisig_n_portal_ohne_oberleitung.3mf, tunnelportal-gewoelbe-zweigleisig_n_portal_ohne_oberleitung.step, tunnelportal-gewoelbe-zweigleisig_n_portal_mit_oberleitung.stl, tunnelportal-gewoelbe-zweigleisig_n_portal_mit_oberleitung.3mf, tunnelportal-gewoelbe-zweigleisig_n_portal_mit_oberleitung.step	€3.90
TT (1:120)	tunnelportal-gewoelbe-zweigleisig_tt_sammelplatte.stl, tunnelportal-gewoelbe-zweigleisig_tt_sammelplatte.3mf, tunnelportal-gewoelbe-zweigleisig_tt_sammelplatte.step, tunnelportal-gewoelbe-zweigleisig_tt_portal_ohne_oberleitung.stl, tunnelportal-gewoelbe-zweigleisig_tt_portal_ohne_oberleitung.3mf, tunnelportal-gewoelbe-zweigleisig_tt_portal_ohne_oberleitung.step, tunnelportal-gewoelbe-zweigleisig_tt_portal_mit_oberleitung.stl, tunnelportal-gewoelbe-zweigleisig_tt_portal_mit_oberleitung.3mf, tunnelportal-gewoelbe-zweigleisig_tt_portal_mit_oberleitung.step	€3.90
H0 (1:87)	tunnelportal-gewoelbe-zweigleisig_h0_sammelplatte.stl, tunnelportal-gewoelbe-zweigleisig_h0_sammelplatte.3mf, tunnelportal-gewoelbe-zweigleisig_h0_sammelplatte.step, tunnelportal-gewoelbe-zweigleisig_h0_portal_ohne_oberleitung.stl, tunnelportal-gewoelbe-zweigleisig_h0_portal_ohne_oberleitung.3mf, tunnelportal-gewoelbe-zweigleisig_h0_portal_ohne_oberleitung.step, tunnelportal-gewoelbe-zweigleisig_h0_portal_mit_oberleitung.stl, tunnelportal-gewoelbe-zweigleisig_h0_portal_mit_oberleitung.3mf, tunnelportal-gewoelbe-zweigleisig_h0_portal_mit_oberleitung.step	€3.90

Printing

1. PLA (or PETG), 0.4 mm nozzle, 0.12 mm layers, 2 walls, 15 % infill, no supports.
2. Face down, as the file is laid out; the joints are bridged.

Installation

1. Stand the portal centred over the track, shim it to rail-top level if needed, test with the check gauge, then build the hill around it.

FAQ

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Version 1.0.0, updated 5 November 2026 · SKU MB-PORTAL-ARCH-2