I’ve noticed that railroads seem to be the most popular topic on this blog… Heck, recently I did an article on LRT routing and got 40 odd readers just off the FaceBook announcement of that article. But railroading can get kinda complicated, so before I weight in on another rail controversy I think I’d best cover some of the basics so I don’t lose most of the audience with rail “techie talk”.

Let’s start with the tracks… Yes, I know, the trains are a lot more exciting. But you can’t run trains without track, in fact trains don’t move well at all “in the dirt”… To the point that the last ditch method of stopping a runaway train is to intentionally derail it. Here in North America you’ll pretty much find those twin ribbons of steel 4 feet 8 and a half inches apart, a standard that came out of civil war experience when railroaders and generals found that having to transfer whole trainloads of supplies between trains due to differing track widths was a major logistical hassle… No wonder that tragic war dragged on so long. BTW, you’ll notice that the railroads are big on standardization- when they’re hooking more cars onto a train at 3 am in the middle of nowhere in the middle of a blizzard, they don’t want to mess with couplers and air hoses that don’t fit. Back to those tracks… You’ll notice they’re pretty big and heavy, and amongst the date of manufacture and other data on them, you’ll find a number, usually over 100. That’s the weight in pounds per yard, and the current mainline standard is around 130 pounds or so. There’s a reason those rails are so heavy- a 4 axle railcar can weight up to 286,000 pounds!

That very gross weight explains why tracks and just about everything on the railroads are built so heavy. Those tracks sit on ties, which despite advances in technology like concrete ties are still mostly just treated wood as they’ve been for over a century. Why? Well, amongst other properties, wood will flex with a load instead of break, and concrete ain’t so good at that. Holding the rails to the ties are a whole system of tie plates and spikes and such, again an old technology that still works best. This all rests on the ballast, and that ain’t just any ol’ crushed rock- The railroads specify the strongest granite because it doesn’t crush under those 286,000 pound cars. But below that lovely ballast, things can get mucky… Most railroads were built before anybody even knew what “soil mechanics” was, so if the tracks sank into the mud, they just dumped in more ballast and raised the tracks! Heck, Union Pacific, who always likes to do things really big, was dumping two trainloads of ballast a day into Great Salt Lake when their tracks were sinking there a few years back. But in contemporary rail construction you’ll see them digging way down to solid ground, then bringing in solid fill and ballast to track level… On the Hiawatha Light Rail Line in Minneapolis, they often went down 10 feet to find solid ground, even on the high ground with it’s gravelly soils. And given that mother nature interrupted terra firma with rivers and valleys, the railroads pretty much developed modern bridge building technology. To this day railroad bridges are built like highway bridges on steroids, and unlike highway bridges, many of them are modular and can be replaced in hours instead of months.

OK, so we got track, and I suppose we could just put an engine on each end so our trains can go both directions. But the slowest train would hold up the rest, and everything would stop while cars are loaded and unloaded… So railroads invented the switch. In it’s most basic form, the switch is a big ‘ol lever and some linkages that literally moved tracks and determined which track a train would go down. Over the years they added a “flag” that indicated which way the switch would direct trains, padlocks so they couldn’t be messed which, and even huge collections of linkages that allowed a strong armed operator in a tower a fair distance away to throw the switches. Nowdays many switches are automated and can be operated remotely from thousands of miles away, and new technology will tell dispatchers and train crews which way the switch is thrown long before a train is too close to stop.

Now unlike highways that tend to follow old trails over hill and dale and around bends with minor straightening, railroads are pretty fussy about their geometry. At best they can handle a 2% grade (a mere 2 feet or rise in 100 feet), and they prefer a maximum grade of 1%. Given that a 100+ car 15,000 ton trains on a 1%  grade can put 150 tons of strain on the couplings between cars alone, one can see why railroads don’t build steep grades. Long railcars don’t like to turn either, and even at walking speed about the tightest they can manage is a hundred yard or so radius curve. Cross section wise, trains tend to be a bit over ten feet wide and twenty foot tall railcars aren’t at all unusual. Light rail cars and some passenger trains tend to be lighter and can turn tighter. All these geometric limitations are a double edged sword… for example, the BNSF track that runs by my abode is at the top of a one half percent grade that slows loaded uphill trains to 15 to 20 MPH… But those gradual grades allow incredibly efficient trains that can carry the load of 400 tractor trailer rigs. We’ll discuss geometry in future posts… Light rail and freight rail can actually share tracks, provided the geometry is compatible.

And how much does railroad track cost? Well, just the sliver of real estate we call a “corridor” can be, as they say in the ad, “priceless”. That’s because even in rural areas it’s difficult to find geographicly linked willing sellers of properties to lay track on, and in urban areas it’s pretty much impossible. Theoretically eminent domain can be used to condemn land for right of way, but in practice that leads to years of litigation. So if you’re going to build a railroad, you’re pretty much going to have to do it in an existing corridor, and it usually makes more sense to buy an existing railroad. Figure on at least $100,000 a mile for just a rural abandoned rail grade and around a million dollars a mile for short line singletrack that won’t cause too many derailments. Want new tracks? Figure a couple million a mile minimum, plus another million a mile if you want overhead wires for electric powered trains, minimum… If you want to build a double track electrified light rail line through a major city, figure on $50,000,000 a mile. Wanna make that a subway? At least double that cost, and maybe even ten times that cost! And you’ve still got to add stations, which can be anything from glorified bus shelters to couple hundred million dollar marvels…

Remember those numbers, you’ll be tested when we examine the runaway costs of light rail and streetcars in future posts. But next up… The trains!

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