One of the ideas I’ve been playing around with is for a post-apocalyptic setting. It started with a zombie apocalypse, after reading a Reddit debate about best zombie-proof vehicle. What I noticed was that most people chose vehicles that were powerful, reliable, had room for survival gear and/or extra passengers, and were difficult for a zombie to stop, damage, or even climb on to.
To me, a train would be the perfect vehicle.
Imagine a single, modern diesel locomotive in good working order. A little research reveals that a single diesel engine’s ability to pull anything is dependent on horsepower, tractive effort, and track conditions (grade). But to us laypersons, a very broad, rough estimate is that a single, modern six-axle diesel locomotive designed to haul a lot of cargo cross-country in more-or-less optimal conditions can pull around 6400 tons, or roughly 40 laden cars (of course different cars weigh different amounts depending on cargo, so 50 cars for one locomotive isn’t out of the question).
OK, so we have a single locomotive and fifty cars, which we want to turn into an apocalypse-surviving mobile stronghold. We’re going to add typical cars in such a way that we get a functional, self-sufficient train that can move from areas of high danger or low resources to high resources or low danger, as needed. First we’re going to need fuel, so at least three tanker cars full of diesel to keep the train moving. These engines use a lot of fuel, but the train only moves when it needs to. That helps. In North America, most tankers are double-hulled DOT-111/TC-111 cars with a capacity of 30,000 U.S. gallons. 90,000 gallons of diesel ought to last a good long while if the train only move when necessary. Maybe some enterprising survivor attaches box cars over the top of the tankers to serve as additional protection and disguise.
Behind the tankers, in the middle of the train, and at the end of the train, is a caboose. The cabooses provide not only convenient toilet facilities and bunks, but the elevated cupola serves as watchposts. Each caboose would be manned by several well-armed guards, not to mention a couple in the engine to protect the engineer. Our current total is six cars.
Since a train can only travel along its track, a damaged track is bad news for our survival train…unless it carries what it needs to repair the tracks. We’re going to need at least one flatbed laden with railroad sleepers and spikes, and a hopper car full of ballast. While we’re on the subject of hopper cars, maybe our survival train has a half dozen half-full of soil, used as mobile gardens. Most likely the survival train would have gardens planted trackside, which in times of danger it would abandon. But a mobile garden would be quite an asset. Since both plants and people need water, we’d better add two more tankers full of water. A little fresh protein is a good idea, too, so how about one stock car full of chickens and another two for cows? The cows would be allowed out to graze when it is safe, but the chickens would be full-time residents of their car. Current total: nineteen cars.
That pretty much covers the necessities, so the remaining thirty cars could be boxcars converted to living areas, supply storage, and the like. Maybe one is a car hauler that holds several road vehicles for off-the-track forays. So how many people could live on our survival train? Well, we have thirty boxcars, each of which is 50′ long, 9′-6″ wide, and 11′ high. Since a twin XL mattress is 3′-3″ x 6′-8″, a row of bunks along each side would leave about thirty inches of room down the middle of each car. Of course, 10′ of the middle of each boxcar is occupied by the doors, so that leaves twenty feet on each side. Each end of the boxcars could reasonable hold twelve people- two columns of three bunks on each side- for a total of twenty four people per boxcar (plus a modest living area in the middle). Or, perhaps each car holds two families of four on average. If you assume one boxcar of supplies is needed for every four passenger boxcars, then our survival trail could easily have a population of between two hundred and five hundred people.
There you have it: a self-sufficient, mobile settlement that can either repel attackers from behind high metal walls, or simply move a hundred miles away to a safer locale. In time, once stable settlements are established in the post-apocalypse world, perhaps the train becomes less of a survival train and more or a trade caravan, moving goods from place to place.