SP Jawbone Branch (Part 6) - Q&A and Continued Design Tweaks

In previous posts I've posted on some of the various operational aspects of my concept for modeling the SP's "Jawbone" Branch.  Since roughly the New Year, I've been pondering the designs I should dive a bit deeper into the discussion on some of the engineering details of how the plan can be actually pulled off.

Note: I wrote this post as "Part 5" before I bought the material and posted the "Part 5 - Pulling the Trigger", forgetting that I had this in the editing bin!  So I've re-edited this post somewhat and it will now be "Part 6".

Staging Yard - A Must Have for Operations

Staging - A critical box to check on any operational interchanging layout.  Three "Decks" ready to lead freights out of Famoso Staging Yard, LMRC.

Freight Car Fleet Size?

Ok, this has to be one of every operating model railroader's blessings and nightmares.  

How big of an operational fleet do I need?  

Currently my expected freight roster of cars I have, or plan to soon have which would be useful and fun... plus a certain "cool" factor is around 80 freight cars that I figure could show up on the branch.  In addition the 'passenger excursion' consist would probably be one that I put together specially and not regularly store those 8-10 cars on the layout.

Well, let's quickly look at my plan again, just as a recap:

Owenyo Local with Extra 3237 East working at Bartlett.  Circa 1950-53, Eddie Sims collection

Owenyo Local (1st Consist) = ~10-15 cars on average pending tonnage proof for engines that will be used.

Cars spotted at Caliente, LMRC.

Cars Spotted on Layout = ~20 cars on average.  Max Capacity ~30 cars, plus about 20 car lengths of run around space at Owenyo for the local to work in turning around.

Owenyo Local (2nd consist) = Another ~10-15 cars, as listed above.

Suitable Pool of Foreign Interchange Cars = ~10-20 cars I figure will allow my foreign boxcars, etc to rotate through and provide some variety to the 'look' of the trains.  This gets us up to about 70 cars total now.

These first two listed requirements will cover the 'regular train' during an operating session.  However we always know that the same group of cars (outside of assigned cars) will probably never return in exactly the same way again.  This will mean that a second consist of local equipment should be kept ready to rotate in from the staging yard and a pool of other 'extra foreign' cars could be stored to rotate through.

SP 73611, an example of an S-40-5 from Red Caboose.

Live Stock Special = 10-25 cars  This consist would obviously be a 'special occasion' consist, but worth running to mix things up.  I don't know if a dedicated staging track would be needed or if I would simply remove some of the extra 'foreign' cars to clear some space for it.  I don't currently plan to operate more than about 3-5 SP stock cars.  So having a full train of these cars is not really in the plan right now, but I should provide for it "someday" rather than not provide for it and then be stuck when 10-15 more stockcars show up when a friend drops by or something.

SP 3237 & 3266 at Searles Station - 5-30-52 - Carl Blaubach photo - Brian Black Collection

Passenger Excursion = 9-12 passenger cars, two engines, two water cars.  For a bit of extra variety the Owenyo Branch is the fan trip and excursions which ran up the Jawbone Branch to visit the SPNG out of Owenyo.

Conclusions About the Fleet Size and Layout Capacity

One of the main things I've learned at LMRC over the 20+ years I've been involved there is that I am a firm believer in that much of the "prototype feel" comes from having the free space and plenty of extra track at the stations.  There is no games of "traffic jam" where you can only move one car to move the next.  At LMRC Caliente for example can fit about 45 cars in the non-mainline/passing sidings.  However, very rarely will the station see more than 20-25 cars spotted.  This leaves plenty of elbow room for switching crews to work the station.  I don't really enjoy working "puzzles" which don't fit well into the prototype 'elbow room' of most stations.

A typical day at Caliente with a work train filling up the 'short' siding. The spurs aren't very full.

The current plan for Owenyo's track capacity should allow plenty of maneuvering room for the local to work.  If I had a crazy idea, I suppose I could have the local in town when the stock special or passenger train show up, but I believe the prototype would have tried to avoid this as the local only ran three times per week, leaving plenty of opportunity for a second train to operate and get in the clear between the regular local.

What size Mojave Staging Yard can I have?

Currently, I plan to have a four-track staging yard.  Track 1, the "Main" will be the front most track (northern in the drawing) and will be a run-around track, which will ideally be kept open for engines to move on.  The next track, Track 2, will be the main 'Arrival-Departure' track where the trains come into, are switched, and depart from.

Mojave Yard with notes of approximate "Cassette" locations

Tracks 1 & 2 will measure about 12.5ft long (~25x45ft car lengths) and have a right-hand crossover with at least 14" (one Mk-2/4 or Mk-6 length) of clear 'head space' at the western most (stub) end as an escape track for the arriving road engine.  The caboose can also be shoved down into this tail before the departing train is shoved together.

Tracks 3 & 4 will be stub-ended storage tracks, each about 30x45ft car lengths long.  These two tracks can have a spare consists of freight cars for the locals, perhaps a 10-15 car livestock cut of cars, or a passenger excursion consist staged.

The crossover at the west end of Track 2, will result in a stub of about 18", which I think will be useful to stash cabooses, extra engine, etc.  Given that it is behind the regular escape track, there shouldn't be any issues seeing or accessing the equipment in this pocket.  One option I'm considering for this crossover is flipping it to a left-hand crossover, which would put the stub on the end of Track 1, the closer track.  This would be ideal if I want to change the stub to a cassette staging option.  If I add the cassette under the south-western curve, it will probably need to branch off east of the crossover, which would make the orientation of the crossover of no concern, other than the run around tail would be better to keep towards the front of the staging yard.

Three of these four tracks will give about 85 cars worth of track space.  This should be enough for my basic operating scheme, so the freight cars aren't constantly being lifted on and off the layout into storage boxes.  From 25 years at LMRC, the majority (probably 80%) of the damage to equipment comes from handling it, dropping it, etc.  I would say less than 20% is from operational damage from actually running the equipment.  The less I have to lift the equipment on and off, the better it will be!

Current Approximately: 170 Cars Max Capacity

Mojave Staging: 110 – 60 storage + 2x25 A/D with one as run around.

Owenyo: 60 - ~20 runaround space, ~12 on-spot
Other Stations: ~ 6-10 spots (average between Bartlett, Little Lake, and Linnie)

Engineering Questions

Let's get into some of the questions of the layouts engineering.

What grades do I need to clear the Mojave Staging Yard under the Owenyo Yard?  

3D view from south side of the layout showing the vertical arrangement of the elements.

Currently I'm considering 1.5% grades in my 3d CAD model of the layout.  I would prefer not to go steeper than this so the Mk-2/4 class engines can handle more than 8-10 cars.  I don't want the Owenyo Local to require a helper all the way to Owenyo, which was not done prototypically.  "Short Helpers" were used on the livestock trains as far as Haiwee Summit, between Little Lake and Bartlett, but I won't really have the space to 'cut' a helper in that area, and on the model the grade will be continuous along the opposite side of the room from Owenyo/Mojave.

How much vertical clearance do I want to have in the staging?  

I'm currently planning for a 3.5" layout top surface to bottom of benchwork.  This will be pretty tight, but it is about all I can spare.  Working the staging yard will have to be done along the front edge or by pulling a string of cars out for flat switching, basically into Linnie.  I do want to consider this, as restaging moves should be clear of the operators' area at Owenyo if I have more than one person operating at a time.

How much structure will I need under the Owenyo Yard?  

I think the 1.5% grade and 3.5" space for staging should allow 2" of thickness for the Owenyo 'benchwork'.   I'm considering using 2" extruded foam with wood edging, rather like we've seen with Luke Towan's dioramas on YouTube.

I may have to play with this method with some material to prove that it will do what I expect.  There will probably still need to be some form of L-bracket on the underside of the layout for the areas at Owenyo and Staging Yard.

As of January 14, 2021, I've picked up 1" thick foam and will probably try to keep the edge supports to ~2" tall and thicker in places where I can spare the vertical space.

How many average cars can I have a Mk-2/4 reasonably pull on a 1.5% grade, a 1.75% grade, a 2% grade?  

The regular "Owenyo Local" engine would be pulled from a pool of four engines based at Mojave.  The lightest of these usually would be 2-8-2s from class Mk-2/4.  One Mk-6 did show up from time to time in the employe timetable's special instructions and ratings.

I hope to soon get the mechanism of the SP 3203 completed, DCC installed, weight set up, and then I could do some 'tonnage testing' and get an idea what grades and train lengths can be hoped for.

Does the wye at Owenyo need to be made larger than 24" radius? 

I believe 24" should be more than enough for the Mk-2/4 and Mk-6 class engine models.  I will need to test this pretty soon to confirm that I don't need to increase the size of the wye.  Looking at how 40ft tank cars will look on the 24" radius curve at the water tower/pump complex, I can't really see going smaller than 24" radius for realistic scenic effect.

 Do I need to offset the wye tail length for the switch on the tail? 

Currently I have the wye planned with only 0.25" extra easement.  I may end up increasing the offset over 24" radius so that I can have smoother easements through the frogs, especially the wye-switch at the tail of the wye.

What will be the rough concept for how the wye tail be 'removable'?

I probably will work on some form of a removable tail for the wye, giving me more room in my shop when the layout is not in operation.

Owenyo Yard showing the plan for the wye tail.  I may cut it off closer to the wall.

I also need to work out two lifting or removable spans for the two doorways.  Yes, some comments have been made about out-ward swinging the doors, etc.  That's not really an option, and I'll leave it at that.  Probably the one just outside of Owenyo will be the main doorway, which I will need to have opening most of the time.  I will probably put in cut-out interlocks so the track will drop power when the bridges aren't in place.  I have also seen some ingenious pop-up pins, plates, etc that will protect equipment from being shoved out an open bridge.  Some method will have to be used, as I don't want Sunset Mk-2/4s going to the floor!

How should I turn the engines at Mojave Staging?

I think that a "Cassette" style section of track could be a really good way to turn the steam engines around when in the staging yard to restage the trains for returning to the branch.  Given that I may want to set up and easily turn engines that I'm doing testing with on the layout, which will not be able to be turned on the wye at Owenyo, an 18-20" long "Cassette" that can be reversed and plugged back into the staging yard area fit the need nicely.

There are two places I see being able to put such a unit.  One is under the curve at the west end of Owenyo, near the tail of the staging yard.  The other is under the 'core' of the wye, where I do not plan to have it being removed.  In both cases an extra switch would be needed on the staging track to allow access to the "Cassette".

Probably in both locations otherwise I would have to keep that track open as a run-around so the engine could come off the arriving train, run to the "Cassette", turn around, then continue to the other end of the staging yard - completing the run around.  If I have "Cassette" docks at both ends of Mojave Staging, then I could (in theory) carry the cassette to the other end of the yard and not need a running track open.

In Closing

This project certainly has me being stretched in some directions I've not gone in a number of years.  I find it fun to see the changes in materials and what's available in the hobby.  On the research front, I'm still trying to gather some information from CSRM related to the 'Val Maps' which I know they have for basically all of the Pacific Lines.  Hopefully my email to CSRM will solicit a response soon.  Until then, I guess I get to pluck away with what I have for information.

Jason Hill

Related Articles:

SP Jawbone Branch (Part 1) - Concept

SP Jawbone Branch (Part 2) - Researching and Changing of the Plan

SP Jawbone Branch (Part 3) - Consists and More Bartlett Research

SP Jawbone Branch (Part 4) - Freight Car Roster

SP Jawbone Branch (Part 5) - Pulling the Trigger (Buying the materials for the benchwork)

SP Jawbone Branch (Part 6) - Q&A Continuing Design Tweaks - Working out the logistics for the staging yards other details.

SP Jawbone Branch (Part 7) - Film & Construction Begins - Historic movie film clip of Owenyo Local and starting construction of the layout.

SP Jawbone Branch (Part 8) - Little Lake Grows - More research materials have surfaced for my modeling of Little Lake

Freight Symbols Over Tehachapi - Part 4 - SP Locals