Archives: Doing the Marengo
My good friend Jeff Mann, the true Yard Ramp Guy, has asked me to revisit some of my original posts. This week in my From the Archives series: can limestone caves save the human race?
A kids' version of the man cave?
Marengo Cave is an enormous, beautiful natural cave in Indiana. It's easily traversable for tourists, isn't particularly muddy or wet, and is absolutely beautiful.
A group of children discovered the cave in 1883, and the townsfolk—immediately recognizing a potential tourist attraction—quickly declared it a protected site. A few years ago, Marengo Cave was declared a US National Landmark.
It's not the only cave in Marengo, Indiana, though.
The Marengo Warehouse is an old underground limestone quarry located just a few miles away from Marengo Cave. Opened in the 1800s, it contains almost four million square feet of storage space (more than 100 acres), about a quarter of which is in use. The owners converted it from a mine to a storage warehouse in response to competition from much larger limestone quarries.
All sorts of rumors swirl around the warehouse. For example, the Center for Disease Control supposedly stored supplies there for a long time, but the only actual government property inside are some 10 million MREs. The other contents of the warehouse include 400,000 tires and some 23 million pounds of frozen fruit, most of which are intended for use in yogurt.
The Marengo Warehouse is nowhere near unique. All around the world, we’ve converted limestone mines into storage spaces and business parks. This depends on how we mine the limestone. Since the 1950s, miners have worked carefully to ensure that the leftover space is actually useful, carefully removing 12-foot thick chunks of stone in grid-shaped patterns. When mining is completed, very little construction is needed to ready a cave for other purposes.
Me…in my man cave.
The underground limestone quarries are extremely stable. Limestone is made of compressed, ancient, tiny seashells. It's three times stronger than concrete, and has been used in construction for more than three thousand years.
Of course, there are certain concerns with use of the quarries. Ventilation is a much greater concern than in other mines, so electric forklifts are generally required instead of those powered by propane powered. And, while the older quarries are generally extremely stable, the geological strata above and below the facility must be monitored, to watch for shifting or cracking rock layers.
Now, I’m way too hopeful a man to get all bothered by doomsday scenarios, but if you really want to start preparing for all possibilities, those limestone caves might one day save the human race. I’ll stick to my man cave…when Maggie lets me, of course.
Archives: Getting to the Cashews
My good friend Jeff Mann, the true Yard Ramp Guy, has asked me to revisit some of my original posts. This week in my From the Archives series: Some nutty blog entry.
That's me, looking for cashews.
Anyone who's worked in shipping—or anyone who has ever opened a jar of mixed nuts—has experienced the same thing, over and over again: When you're moving a jumble of little stuff, the big items (or Brazil nuts) always end up at the top.
At first glance, it seems simple enough: the smaller stuff can just fit down into the holes between everything else. Problem solved. Except...if that were true, then the small stuff would be at the bottom but the big stuff would still be scattered all the way through.
Well, what about density? If the big items are just less dense, they'd pop right to the top, yes? Well, sometimes, though much denser large objects also tend to rise to the top. It's only the items with a slightly different-than-normal density that remain scattered throughout.
In order to understand this, we need to view it a bit differently. Let’s approach it in terms of convection. In a liquid, temperature and pressure differentials can create convection currents that move particles around in huge looping patterns. If you treat the mixed nuts as a fluid, convection actually starts to accurately model what's going on. (Scientists call it granular convection.)
As it turns out, both of our previous ideas were almost right. As we move the box around and shake its contents, we force the particles in the middle upward in a current. The particles on the sides then fall into the gaps left by the rising particles in the center. Which is where our first idea comes into play: the smaller particles can fit down into the new gaps more easily, leaving the biggest ones on top.
Found 'em.
We still have the density issue confusing things, though. And this we can't solve quite as easily. We know what happens, and we have an idea how it happens (weirdly enough, density doesn't particularly affect granular convection on this scale if the mixture is in a vacuum), but we still haven't put our fingers on all the whys.
One thing is for sure, though: Cashews are definitely the best. You'd have to be a fool to think otherwise. (Well, the almonds can stay, too.) Brazil nuts and all the rest are just something you have to endure for the sake of the cashews.
Archives: Cable is the Real Web
My good friend Jeff Mann, the true Yard Ramp Guy, has asked me to revisit some of my original posts. This week in my From the Archives series: Cable...is what's for dinner. And breakfast. And brunch. And lunch.
Cable: The (wet) Connection
I've heard everyone—from my coworkers to the news outlets—describe ours as a wireless society. Nothing could be further from the truth.
A fun little statistic: In 2006, we transmitted less than one percent of all international data traffic via satellite. The percentage is a little higher today, but we continue to route the overwhelming majority of data through undersea fiber optic cables that stretch between every continent except Antarctica. Countries around the world consider them absolutely vital to their economies.
We've been laying underwater cable for a long time. Those first put into service were telegraphy cables, laid in the 1850s, though experimentation with the cables went back as far as the early 1840s (just a couple years after the invention of the telegraph). And during the Cold War, the United States and the Soviet Union tapped into and cut each others' cables.
Laying the cables today is immensely expensive. We spend billions of dollars each year on the process. And, while the cost has gone down a bit, it's still normal to see price tags hitting tens of thousands of dollars per mile.
Submarine cables also break, and they break frequently. Fishing trawlers, anchors, earthquakes, turbidity currents (giant underwater landslides), and shark bites are all major causes of these breakages. We're not entirely sure why sharks like biting them so much.
Repairing them is a difficult and costly process, involving specialized repair ships that lower grapples to lift the broken ends of the cables to the surface for repair. We employ different types of grapples, depending on the seafloor around the break (for example: rocky vs. sandy). In shallower waters, we can use submarines to repair the cables.
Politicians thrive on producing drama about literally anything. While drama over oil and such tend to hog most of the media attention, submarine cables are a really big deal.
Archives: Raising a City
My good friend Jeff Mann, the true Yard Ramp Guy, has asked me to revisit some of my original posts. This week in my From the Archives series: It turns out that buildings can be very moving experiences.
Stay with me on this one: yes, it begins on a pretty sour note…but I promise you there’s a happy ending.
Raise High the Roof Beams, Carpenters
Nineteenth century Chicago was plagued by, well, plagues. Epidemics of typhoid fever, dysentery, and cholera repeatedly hit the city. The 1854 cholera outbreak killed six percent of the entire city's population.
The reason for those diseases, and a common culprit throughout history: poor-to-nonexistent drainage. Standing water in a city makes a perfect breeding area for all sorts of nasty illness. In fact, disease historically was so bad that the majority of medieval cities experienced negative population growth—more people died of diseases than were born.
The only reason cities didn't depopulate was a near constant influx of immigration from the country. This changed steadily around the world when city infrastructure and medicine improved. Disease was still quite common in the 19th century, but Chicago's level of disease was quite unusual in an American city for the time.
In 1856, an engineer named Ellis S. Chesbrough developed a plan for a city-wide sewer system that would solve the problem. It was unusually ambitious: he wanted to raise the entire city six feet, then build sewers below the newly raised buildings.
Sounds insane, right? That's what I thought, too, except they actually did it—raising the first building in January 1858: a four-story, 70 foot long, 750-ton brick structure lifted on two hundred jackscrews to its new level, without the slightest damage. Engineers boosted more than 50 masonry buildings that year alone.
In 1860, a team of engineers actually managed to raise up half a city block in one go—an estimated 35,000 tons lifted nearly five feet into the air by 600 men using 6,000 jackscrews. They were so confident in the process that businesses didn't even close during the the five days it took to lift the whole thing.
On the last day of the process, before they began work on the new foundations, they allowed crowds to walk underneath the buildings, among the jacks. At another point, a six-story hotel was raised up without the guests even realizing it.
Only masonry buildings were considered worth raising; they placed wood-framed buildings on large rollers and moved them to the outskirts of town, usually without even bothering to empty out the furniture first.
This was so common that, for quite a few years, people considered looking out the window to see a building going past just another day of normal traffic.