Decision Matrix - the 300th Post



A few years back I was having trouble deciding on what layout to build. I had a bunch of N Scale modules and was trying to build a double deck layout. I had all the bench work done, but in looking at it I knew something was wrong. So I took an idea from work and built a decision matrix to help me sort out my thinking. I published this in a article in Model Railroad Planning 2006. You can see a copy of it here. I have an archived copy of the former layout website here.

When I decided to stop building my DRGW Tennessee Pass layout, I redid the matrix and discovered that the C&O Mountain Sub layout actually fit my givens and druthers (G&D) better. That matrix wasn't published, but the C&O Mtn Sub scored a 103. I had become bored with the Tennessee Pass layout by then, so I welcomed the change and started building the C&O Mountain Sub layout using my existing modules as a start. That layout was in Great Model Railroads 2011.

I have already related how I decided to switch to the USMRR Aquia line earlier in the first posts to this blog. But I never did a design matrix for it. Yesterday, Marty McGuirk was cleaning out old emails and sent me a copy of the C&O Matrix with a jibe that I should tear out the USMRR and go back to the C&O since it had the highest rating. That got me thinking, how would the USMRR Aquia Line score on the matrix, using the same criteria.

So I redid the matrix comparing the USMRR to the three previous layouts I was building in this house. Turns out, the USMRR scored highly, but not as high as the C&O Mountain sub. But it soundly beat both of the DRGW layouts.

This doesn't mean I am going to tear out the USMRR layout. The matrix is a decision aid and not a hard and fast rule. One of the most useful things you can do with the matrix is a sensitivity study. That is where you vary your G&Ds and weightings to see what how things compare.

I scored the USMMR a 2 for manageable  instead of a three because the wiring and track are simple, but I have to scratch build it all. If I had scored it a 3 the USMRR would have come out on top. The USMRR has the best waterfront design of any layout I considered. The others don't have a waterfront, but there were other plans I considered that did, so it is not a goofy as it looks. 

 I gave the USMRR a high score on big steam, not because it has C&O 2-6-6-6 H-8s and K4s but because the SMR 4-4-0s are big, beautiful and sound great. If I threw in battery power (assuming it works) then I'd add points for manageable and big steam.  I gave the USMRR 3 points for prototype modeling because of the information available at the National Archive. I would never have such good data on the C&O, and I had even less on the DRGW.

I could also change the G&Ds. When I built the matrix I was mostly comparing N scale layouts to each other. I did not look at different scales. Thus, the opportunity for figure modeling that O scale provides was not even a consideration in N scale. If I were starting from scratch, I'd add a G&D for figure modeling and that would tip the USMRR to the top. I could also add a G&D for the military modeling tie in. But if I did that now people would say I was cooking the books like a good beltway bandit.

So, it was a fun exercise.

As to swapping prototypes again, given that I am 55 years old and this project will take another 5 years, I probably won't build another "lifetime" layout. My next layout projects will be smaller, similar to British exhibition layouts. Some subjects I want to pursue once the Aquia line is "done" include a 1920s era steel mill in HO or P48. I also am intrigued by the idea of a Russian Front WWII depot in P48 using US Lend Lease equipment as well as Russian motive power (see the movie "Ballad of a Soldier" for inspiration.) It would feature some of the cool Tamiya 1/48th scale armor models now coming out. It would include an urban scene, perhaps battle damaged.

I just noticed that this is the 300th post to the blog. Amazing. Congrats to those to you that have stuck it out with me this long.