Section 12 - Tunnel 1 - Part 1

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.

North Portal

South Portal

 

 

 

 

 

Layout Design Elements

Tunnel 1 is the lower reach of the Polson Canyon river valley. It has amoderately steep hillside and rock faces, with a sparse growth of second growth conifers, dead trees, stumps and bushes. The right of way parallels a ridge line on the east side (backdrop) and the Satsop River on the west side (fascia). 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 module and consists of eight design elements (from geographic north to south):

1. A single track main line from Polson Canyon to Sawmill.
2. A curved river valley with moderately steep ridge with a sparse growth of second growth conifers, dead trees, stumps and bushes. 
3. An embankment to the river.
4. A heavy growth of shrubs and bushes at the river's edge. 
5. A single track tunnel bored into a saddle in the ridge.
   
6. An abandoned right-of-way (formerly OPLC main line to Camp 3) crossing the WWSL main line.
   
7. A turnout off the WWSL main line to the OPLC arrival/departure track and industry complex.
8. A 90 foot turntable owned by the OPLC in support of the Sawmill operations.

Module Construction

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 a lolly post).  It follows standard section construction, except it has a third 2"x2" and 1"x3" girder in the middle. 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 (60 - 4 - 4 = 52/2 = 26 (a 24 inch radius when laying out the curve from the interior).

Because this section ties into both the Section 11 - Sawmill and the Section 13 - Polson Canyon, some right of way 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 main line at Sawmill (4.5 inches from the fascia).

1. easement  - simple curve - Tunnel 1 - simple curve - easement  (the turnback curve).

5. 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 10 inches clearance at the Tunnel 1 - Polson Canyon and Tunnel 1 - Sawmill connections for turnout placement.

6. The dismantled Camp 3 logging roadway will have indications of a crossing that has been taken out. See 4.2.11.12  Modeling Technique for Dismantled Roadbed for details.

7.  

8. The turntable at Tunnel 1 was initially used by the OPLC for operations from Sawmill to Camp 9 (OPLC's western main line). Once main line operations were transferred to the WWSL, the turntable was decommissioned.  It was restored to service when the planing mill loading operation became mechanized and required boxcars to be turned. 

Laying out the Structures

 

There are five structures to be laid out: 1)  North Tunnel Portal (slide shed), 2) Tunnel Bore, 3) South Tunnel Portal (Concrete), 4) a section tool shed, a hand/motor car turn-off shed for a tunnel inspection car, and 5) a 90 foot turntable.

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

North Portal

The North Portal will be a re-creation of the Homestake Pass MT, west portal, NP Tunnel #5. It has a timber portal and a rock slide shed. I will represent the latter with a timber tunnel lining and a timber rock shed that extends from the portal. 

 

See 4.1.10.1a Tunnel N1 North Portal for construction details.

See 4.1.10.1b Tunnel N1 Rock Shed for construction details.

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  

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

I built structure footprints for each of them for conformation of siting those structures.

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: 

1. Lay out the main line curves. It is a simple 24 inch turnback curve, with north curve at the 6-inch line, the tunnel curve at the 6-inch line, and the south curve at the 4.5- inch line.
   
2. Lay out the tunnel template.
3. Lay out the north and south tunnel portals. 
4. Layout the northern switch to the OPLC main line and sawmill complex. 
5. Layout the turntable approach track from the sawmill yard and spurs.
6. 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. Per specifications there should be at least 2 inches of straight track before reaching the module edge.

Roadway Details 

• Tunnel 1 Roadway is WWSL Medium Profile Roadway. See 4.2.11.2  Modeling Technique for Medium Profile Roadway for details.
• The roadway in the tunnel bore has different drainage engineering requirements.See 4.2.11.16 Modeling Technique for Bridge Roadway for details.

Catenary

As this mainline is electrified, the tunnel bore and portals will have a higher clearance profile than normal. See 7.1 Cantenary Systems Overview for details.

Right of Way Drainage.  See 4.1.8 Ditches, Drains and Culverts

• Drainage. The tunnel will have tunnel specific drainage. See xxx.xx.xx for details.
  
• Culverts

MOW Details

• 4.2.12.4 Hand or Motor Car Set-off Detail
• 4.2.12.5 Rail Rests
• 4.2.12.6 Tie Stack Detail
• 4.2.12.7 Equipment House Detail

Track Details.

In addition to identifying cantenary pole locations.

OPLC will use 4-bolt rail joiners on all track. OPLC uses medium mount switch stands.

In the next blog (Section 12 - Tunnel 1 - Part 2) I will discuss the Landform Design Considerations.

Reference