Mushroom design details

Givens

• Layout space will be built in an air-conditioned 28’4”x32’4” room in our detached garage/workshop
• 2x4 wood stud/drywall walls
• 10’ ceiling
• Concrete floor (I will install random 24” carpet tiles)
• HO gauge
• DCC controlled
• Primarily Union Pacific

Druthers

• Long mainline run
• Linear follow along design
• Support long (200”-220”) trains
• One pass through each scene
• Minimum 3 ft wide aisles, Prefer 4 ft aisles
• No crawl unders, duck-unders, etc lower than 75”
• Division Point yard (freight classification, passenger terminal, steam and diesel service, turntable and roundhouse for 4-8-8-4 locomotives)
• Large articulated steam locomotives must operate reliably and look reasonable
• Minimum Radius
  • Visible mainline 32” (Prefer 36+ where feasible)
  • Hidden mainline/staging 28”
  • Spurs/Sidings 28”
• #8 turnouts on mainline, in passenger terminal, and in locomotive service terminal.
• #6 minimum turnouts on spurs and in freight yards.
• Peco code 83 turnouts/track on visible mainline. 
• Peco code 100 large insulfrog turnouts in hidden/staging areas.
• Continuous operation possible (automated return loops are ok).
• Turnouts controlled via fascia switches and DCC
• Turnout routing status display lights on fascia.
• Occupancy zones/status indicators on fascia for hidden staging
• Layout will be built to a mid 1950s time period. However this will not constrain the motive power.
• One major city + additional smaller towns
• Emphasis on coal operations as suppliers/consumers/hauling
• Cattle stock yard + Processing industries
• Some mountainous terrain – canyons with bridges/trestles
• Union Pacific + Coal Hauling RR that shares trackage rights

Possible locales

• Pocatello/Idaho Falls/Dillon/Butte
• Ogden/Brigham City/Tremonton/Wheelon (I chose this option, however in my world Ogden was founded by Pirates of the Great Salt Lake and the Utah Railway has trackage rights farther north than in the real world)

I enjoy all aspects of building:

Benchwork
Laying track
Electrical
Structure building
Scenery

I am a Model Rail-fan and Photographer

I like watching trains run

I am not currently into operations and I am not sure if I will ever get into operations, but the design should reasonably support operating sessions with up to 12? participants.

I am fairly proficient at bench-work building, electrical, etc and I own all the tools required to build the infrastructure for a layout of this size.

How well does the design meet my ‘Druthers’?

• Long mainline run - Mainline run is 450+ ft from lower return loop to upper return loop, 520 ft from lower city branch-line end to upper branch-line end
• Linear follow along design - Yes
• Support long (200”-220”) trains – Shortest staging or passing track is 230” long
• One pass through each scene - Yes
• Minimum 3 ft wide aisles, Prefer 4 ft aisles – Aisles are 4ft, except 3 ft in room door entryway and 3.5 ft in loco service aisle, 30” wide entrance stairs to upper level center platform
• No crawl unders, duck-unders, etc lower than 75” – Railroad Bridge across aisle from middle level to upper level is 78” above floor, Upper level ‘wing’ benchwork is 74.5” minimum above aisles (One wing is 74.5” the other is 76.5”)
• Division Point yard (freight classification, passenger terminal, steam and diesel service, turntable and roundhouse for 4-8-8-4 locomotives) - Yes
• Large articulated steam locomotives must operate reliably and look reasonable – We’ll have to wait and see
• Minimum Radius
  • Visible mainline 32” (Prefer 36+ where feasible) – Visible mainline has minimum radius of 40”+ curves
  • Hidden mainline/staging 28” – Yes, except for the lower level inside return loop staging track is 26.5” radius,
  • Spurs/Sidings 28” - Yes

• #8 turnouts on mainline, in passenger terminal, and in locomotive service terminal. - Yes
• #6 minimum turnouts on spurs and in freight yards. - Yes

Known issues and remediation plan

• The ‘downtown’ city scene is deep (36”).  The backdrop in this area will be removable and the benchwork will be built to provide access from the back side.
• The roundhouse/loco service area is very deep (48”).  The backdrop in this area will be removable to provide access from the back side aisle.
• The middle level above the roundhouse/loco service area has a very long reach.  The backdrop in this area will be removable to provide access from the back side aisle.

Misc notes

The lower level nominal track elevation is 42”.  The branchline in the city of Ogden is at 43” and the return loop/staging track under Ogden is at 37”.

The middle level nominal track elevation is 62”, however around the center of the wall above the division yard the track starts climbing from 62” to 78” (1.8% grade). This will be a helper district.

The upper level nominal track elevation is 82” with the center platform floor at 30” provides an effective elevation of 52”.  The upper level branchline climbs up to 88” above the upper return loop (82”).

The double helix has radii of 37.5” (1.69% grade) and 40” (1.59% grade)

I have not yet added all the industry service sidings/spurs.

I have not 100% decided what I am going to use the branchline area above the upper level return loop for (nice sized town or large industry).

Layout Operational Stats

Using 6” car length

Operational Stats

Maximum number of cars = 755

(80% * (storage + staging + passing/2) = .8 * (425+414+210/2)

Maximum cars to Maximum Mainline Ratio = 755/1200 = 62.9%

Number of cars moved = 616

(40% of (staging x 2 + passing + connecting)) = .4 * (414*2 + 210 + 502)

Trains (616/42 ) = 14.6

Dispatching Threshold = 47

(3 x shortest passing siding + 2 x average passing siding + longest passing siding) / 6) = ( 3 * 38 + 2 * 52 + 65 ) / 6

Staging Tracks

Lower Loop ( 45, 44, 43, 42, 40 )

Upper Loop ( 41, 40, 40, 40, 39 )

Passing tracks (Upper: 42, Middle: 38, Lower: 65, Helix: 180 (65))

Using 7” car length

Operational Stats

Maximum number of cars = 649

(80% * (storage + staging + passing/2) = .8 * (364+358+180/2)

Maximum cars to Maximum Mainline Ratio = 649/1086 = 59.8%

Number of cars moved = 531

(40% of (staging x 2 + passing + connecting)) = .4 * (358*2 + 180 + 431)

Trains (531/34) = 15

Dispatching Threshold = 41

(3 x shortest passing siding + 2 x average passing siding + longest passing siding) / 6) = (3 * 34 + 2 * 45 + 55) / 6

Staging Tracks

Lower Loop (38, 37, 36, 36, 35)

Upper Loop (38, 36, 35, 34, 33)

Passing tracks (Upper: 36, Middle: 34, Lower: 52, Helix: 154 (52))

I forgot to add that with the

I forgot to add that with the 10' (120") high ceiling and the 30" high center platform the effective ceiling height inside the mushroom is 90" (7'6").

Great prep work

Do you have a start date?  When ever I seriously think about this kind of layout, I come back to the feeling that it is like building a small custom house within a single room.

I would love to see how and where you start, and the various steps in the construction process.  I hope you post that progress here.  I'm sure there will be a lot of interest.

Do you have a start

The GC is done with his garage construction tasks as of today. I have about a months worth of DIY tasks to complete before starting on the layout construction. I plan to maintain a blog covering the construction of the layout.

I plan to install an epoxy floor in the garage/woodshop areas and I need to seal the concrete floors and lay carpet tiles in the model workshop and train room.