Selecting Rolling Stock for the Model Railroad

 If the locomotives are the heart and soul of the railroad then the rolling stock is the body.  No matter what style of model railroad you plan to build you will need a good number of cars to populate it.  But like the locomotives, if you don't have a plan it is VERY easy to loose your focus and end up with more than you need or can use.  Here are some of the considerations I am using for selecting my rolling stock.  Some assumptions here, you already know your era, scale and railroad.

1. What cars do you like? - This is really important, buy what you like.  I feel that it is a good thing to use your likes and interests to drive how you build your railroad.  In fact, I think it is critical.  If you love long passenger trains then that is what your should be collecting and building towards.  If you love intermodal trains you should focus your collection on that type equipment.  The type of cars you like and you want to run on your railroad have a big influence on later design considerations.  If you work this out now you will have less issues with getting your cars to work after the track is down.  It is best to make sure the cars you are collecting also relate to the engines you are collecting.  Some combos just don't look right.
2. Match your cars to your chosen railroad - For freight operations I think it is important to collect about 60% of your fleet to match your chosen railroad.  Most railroads would quickly ship out cars that belonged to someone else, so you will see them but they should not be the majority.  Depending on the type of cars you might not have options for your specific railroad but you will have leasing company cars.  Tanks cars are usually owned by a leasing company and are not as common in specific railroad livery.  If you are doing passenger trains then the cars should ALL be from your chosen railroad.  They cars never left their home system so would never mix with other railroads.
3. Match your chosen era - many cars cover more than one era of railroading and it can be tough sometimes to know what will work.  Many of the models will have the build date or new date printed on the car.  This will help determine if a particular car makes sense on your railroad. If you are modeling the 1950s then a car built in the 1970s will likely be out of place.  You may have to do some research in order to make good selections but this can be a fun part of the hobby.  

Personally, I really like the ACF center flow 2-Bay covered hopper.  These cars are used for cement and other granular products.  They service very gritty and dirty industrial sights.  They get a lot of wear and tear and are great for lots of weathering. They are short cars that will work well on tight curves and in small industry locations.  This is one of the main types of cars I am currently collecting and a cement plant will be the first industry I model.

ACF Center Flow 2-Bay covered hopper

Because I now know I will include a cement plant on my layout I now have a couple more car options that can service the industry.  One is the ACF 70 ton 2-bay covered hopper.  These are a much older car type but were still around in large numbers in the early 90s.

ACF 70 ton 2-bay covered hopper

Sometime in the 90s (I'm hoping it was early to mid 90s) the Trinity 2-bay covered hopper began to enter service.  For my purposes these would be VERY new and still clean and pretty cars.

Trinity 2-bay covered hopper

So we have one industry that can be serviced by three different types of cars (if we want to do that).  The next question that comes to mind is how many cars will actually be needed?  At the bare minimum I will need two cars - one to be at the industry and one to swap it with during operations.  Because these are small cars, it should be possible to have more of them in a given space.  I am shooting for an industry that can hold 6 cars.  This means I will need 12 total to service it.

Another car I really like is the 40ft Hi-cube boxcar.  These cars were built in the late 60s and were initially used for appliances and other bulky items.  They were never a very common car and I really have no idea if there were in Phoenix in the 90s at all.  In fact, by the mid 90s most were gone.  In their later service like these cares were commonly used for paper mill service hauling large rolls of paper.  For me this makes them a good choice as there are several paper mill/paper product companies locally that are still serviced by boxcars.  The 40ft length makes them easier to navigate on the railroad and have the same advantages as the hoppers.  Most of these cars would have been pretty well worn by the late 80s and so would have lots of weathering.

40' outside braced hi-cube boxcar

Including a paper mill/paper products industry in my era is very easy.  These are mostly just concrete "tilt-up" buildings and are very easy to model.  This industry in the late 80s and early 90s would have also been serviced by FMC Railbox 50' cars as well as 50' hi-cube cars.

50' smooth side hi-cube boxcar

50' FMC 'railbox' double door boxcar

Once again we have a single industry that can be serviced by three different cars.  Additionally, these cars also service other industries allowing for lots of re-use of the collection.  How many cars will I need for the paper mill industry?  That will depend on the amount of space available on the layout but, like the cement plant, I will need two cars minimum.  I expect that it will be serviced by three cars requiring 6 total for operations.

This exercise is repeated for each car type in the collection (or that you want to add to the collection) and each industry.  It take time to sort through this and build a plan but if you do this you can keep your collection manageable and usable on the model railroad. Remember, every dollar you spend on cars is one less for other things your railroad will need.