Model Train Layouts & Track Plans

Home Atlas Granite Gorge & Northern

A nice representation of the original Atlas track plan created in SCARM by Ian Donohoe with some modifications and additions. It has many details and custom-created objects and is suitable for running of short passenger and freight trains.


Scale & Size
Scale: HO (1/87)
Size: Medium
Dimen­sions: 274cm x 152cm; 108" x 60"; 9′ x 5′
Area: 4.18m2; 5yd2
Time & Theme
Epoch/Era: III, IV, V / Transition, Modern
Theme: Fictional
Location: United States
Scene: Mountain, Riverside
Tracks & Route
Trackage: Atlas HO Code 100
Type: Closed Route
Line: Mixed (Single + Double), with Branch(es)
Min. radius: 457mm; 18"
Turnout angles: 12.5°, 9.5° (#4, #6)
Features & Control
Traffic: Passenger, Freight, Shunting/Switching
Power supply: DCC
Turnouts: Electric


The track plan features a long main line, passing via several bridges over the river and going in the tunnels under the mountain.

Notes from the author

1. Though no flex-track is required, this plan does require cutting 3 standard Atlas Code 100 Set Track pieces in half in order to fit the central crossover loops within 9' x 5' (without altering the overall layout and track separations). One 9" straight was cut in half to replace consecutive short sections and 2 x 18"R/15° sections cut to make 4 x 18"R/7.5°.

2. This has been a very popular layout since first published by Atlas many decades ago. However, because it only has a small yard and very small industry siding, it is more of a 'show' or demonstration layout to “wow” spectators than a working layout for large trains and yard operations. It is also quite a complicated layout for a beginner to construct. Notwithstanding that, I'm currently adding a variation of it as a mountain excursion from my main layout (though using flex-track).

3. This SCARM layout follows the exact shape and alignments of the original published Atlas HO-28 'Granite Gorge & Northern' plan throughout (plus an added siding in the yard), though most track pieces were shuffled to maintain strict joining tolerances in SCARM (I have found that this entirely eliminates derailment problems in practice). Such tolerances are usually unable to be achieved when joining many set track segments on a long curve on a real layout without a plan. As is often reported on the internet, the original published plan is wildly inaccurate and would have been copied with pencil and paper from an actual manual layout where joins and alignments had been "nudged" to fit – in places by up to 7.5° – and with gaps between rails at many joints and most turnouts. It would have been a derailment nightmare!

4. It will be noticed that turnouts on inclines are actually flat. This is because the current version of SCARM only allows a single height for all three points of a turnout. The turnout height has therefore been set to the average of the three join points of the connecting track segments.

5. The scenery added here is just a quick attempt to get the overall 3D feel and scale of this layout. Most detailed 3D objects I created myself (the locos, the freight cars, the station, the bridges and some other Atlas track accessories) while two buildings are shared objects from other SCARM users.

6. With DCC and computer-based signal and switch automation, it is possible to run up to 5 short trains simultaneously on this layout – each switching between inner, outer and crossover/branch loops to a 'schedule – or by running one or more manually and the rest automatically – while allowing the computer to override the manual throttles to avoid collisions and block violations. See this in action at

Project: Layout   
Author: Ian Donohoe   
Designed with: SCARM
Posted on: 21 Dec 2014
Views: 63415
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