Its time to layout the Section 12 - Tunnel 1 section. The layout design given and druthers of this section is identified in Station 12 - Tunnel 1.
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| North Portal |
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| South Portal |
Design Elements
Tunnel 1 is the lower reach of the Polson Canyon river valley. The right of way tunnels through the ridge line paralleling the Satsop River and approaches the Olympic Peninsula Logging Company sawmill.
This Section consist of one section and consists of layout design elements (from geographic north to south):
- A single track main line from Polson Canyon to Sawmill.
- A single track tunnel.
- An abandoned OPLC logging line crossing the WWSL main line.
- A turnout off the WWSL main line to the OPLC main line and industry complex.
- A 90 foot turntable owned by the OPLC in support of the Sawmill operations.
This section is a turnback curve portion of the WWSL layout. It is approximately 5 foot wide by 42 inches in depth (restriction due to lolly post). It follows standard section construction, except it has three 1x3 girders The two ends of the section are cut out to permit attachment of the module electrical connectors and section interface bolts. See the WWSL section construction reference page for the construction technique.
ROW Design Considerations
The most critical design considerations on this section is curvature of the main line. The turnback curve section width is 60 inches. Technical specification is a minimum 4 inches between track and the edge of the fascia. This restricts the turnback curve to 48 inches (24 inch radius).
Because this section ties into both the Section 11 - Sawmill and the Section 13 - Polson Canyon, some layout of those sections will need to be done at the same time, primarily the main line locator at the southern-most Polson Canyon curve (6 inches from the fascia ) and the WWSL and OPLC main lines at Sawmill (4.5 inches from the fascia).
2. Curved track within a tunnel is generally rare, but not unheard of, in the prototype. It is more common in railroad modeling layout design. The location of the tunnel and the restrictive view minimizes the suggestion of a curve within the tunnel.
I have located the main line at the tunnel entrance 7 inches from the fascia. This allows me to model some portion of the ridge on the outermost side of the tunnel complex. It also allows for removal of part of the fascia to access the tunnel for cleaning and (god forbid!) re-railing errant rolling stock. I'm thinking clear plastic/lexane so that visitors can see the prototype engineering and construction technique used in building the tunnel. This allows 10 inches clearance at the Tunnel 1 - Polson Canyon and Tunnel 1 - Sawmill connections for turnout placement.
Laying out Right of Way
I am not going to go into great detail about putting down the roadbed lines. See the Right of Way Reference Page for the details if you haven't had the fun to do it before.
Essentially you're going to follow this process:
- Lay out the main line curves. It is a simple 24 inch turnback curve.
- Lay out the tunnel template.
- Lay out the north and south tunnel portals.
- Layout the northern switch to the OPLC main line and sawmill complex.
- Layout the turntable approach track from the sawmill yard and spurs.
- Generally locate the turntable location.
Laying out the Turnout
A turnout is required to connect the WWSL main line with the OPLC main line, arrival/departure track, yard lead track and and industrial spurs.
Laying the track. Tunnel 1 Roadway is WWSL Medium Profile Roadway. See 4.2.11.2 Modeling Technique for Medium Profile Roadway
for details. See 4.2.3 Laying Straight Track and 4.2.4 Laying Curve Track for construction details.
Laying out the Structures
Tunnel 1. There are three parts to a tunnel, the tunnel portal, the tunnel bore, and the tunnel lining. See 4.1.10 Tunnels for basic tunnel engineering information.
North Portal
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| North Portal |
Tunnel Bore
The
tunnel differs slightly from the traditional tunnel in that it has an additional height due to the electrified zone. The drainage profile will differ as well. The fascia will be removable
to allow viewing of the interior. See 4.1.10.1b Tunnel N1 Tunnel Liner for construction details.
Southern Portal
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| South Portal |
The
south tunnel entrance will be a re-creation of the April 2002 Mainline
Modeler cover photo.
The rock wall will be constructed with vertical 1 and 2 inch styrofoam insulation with a rock casting overlay.
I will represent the latter with a concrete portal. See See 4.1.10.1a Tunnel N1 South Portal for construction details.
MOW. There will be a section tool house and tunnel inspection car pull off.
Turntable
TBD
In the next blog (Section 12 - Tunnel 1 - Part 2) I will discuss the Landform Design Considerations.
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