56.MRH14-10-Oct2014-L - page 7

and northern California to the more modern and less steep
Willamette Pass route.
My Siskiyou Line also includes the Coos Bay coast branch. I
wanted this branch to have two 24-car trains per day, one each
direction. If you do the math, that’s 48 cars coming and going on
the branch every op session.
The track planning formulas told me that 48 cars moving per
op session was about 40% of the total cars the line should hold.
Doing the math, 48 cars is 40% of 120 cars.
This told me I needed, first of all, a yard capacity in Coos Bay
yard of about 120 cars. My design didn’t anticipate anywhere
near that many cars.
Second, I also needed 120 cars worth of industry on the branch
for this to work. Otherwise we were just moving cars around
with no real reason to be going down the branch!
The formulas further told me the 120 cars parked at industries
needed just a bit of wiggle room, so the 120 would be 80% of
the total industrial capacity of the branch. That means the total
industrial capacity of the branch needed to be 150 cars.
Thanks to these formulas, I could “back in” to the operational
behavior I needed for the Coos Bay branch. No longer was
I just drawing lines on my plan because they looked cool. I
went on a mission to get the needed car capacity into Coos
Bay yard (120 cars).
Once I got the yard capacity up to 120 cars, then I went on a
crusade to add enough industrial spurs to the branch to get
150 cars of storage capacity at industries. I did manage to get
this amount of industrial capacity on the branch, hooray!
I find it’s really helpful to have these formulas to work with,
because they take track planning from being a black art built on
lucky guessing, or cramming in as much as you can “just in case,”
Publisher’s Musings - 3
MRH-Oct 2014
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