Apocalyptic snow in Boston has turned some intrepid---others might say insane---cyclists into ad hoc civil engineers. When Ari Goldberger and his friends found a 15-foot snowbank blocking a bike path, they dug a tunnel 40 feet straight through to the other side, structural analysis and safety standards be damned.
These folks aren’t professional engineers. As far as anyone can tell, they simply saw a whopping pile of snow, grabbed shovels and started digging. This kind of "get 'er done" attitude inspires you to give up on government agencies and just do it yourself. Of course, it also brings to mind newscasts that begin, "Several cyclists were killed today when...."
We’ll never know how well the tunnel would have stood the test of time, because someone---“vandals,” according to news reports---destroyed it over the weekend. Perhaps they hate cyclists. Maybe they were thought the Celtics won the NBA Finals and they felt like rioting. Or that the Red Sox won the World Series and they felt like rioting. Or that it was Pumpkinfest and they felt like rioting.
>The fact that the crew managed to dig the tunnel without it immediately falling in on them is a good sign.
Or it could be that they felt a sense of civic duty to destroy what they saw as a ready-made grave waiting to swallow unsuspecting riders. If that's the case, they might have acted prematurely.
“The guys did a great job,” says Doug Washer, CEO of Head-Line Mountain Holidays, a Vancouver-based luxury adventure provider that builds “snow hotels” for clients. Without the chance to feel the snow with his own two hands, Washer can’t guarantee the tunnel was solid, but based on videos, he’s impressed. The use of an arched roof shifts the weight of the overhead snow onto the walls of the structure. It was no wider than it needed to be, which also was smart.
The fact that Goldberger’s crew managed to dig the tunnel without it falling in on them is a good sign in terms of load testing, says Paul Kassabian, a Boston-based structural engineer and lecturer at MIT. "Tunnels work very well as a structure based on how good the material around them is," he says. And snow is a pretty good building material: It naturally compacts over time, making it more solid (until it melts).
The big question is, how dense was the snow? We can’t say for sure, but it looks like tough stuff. The snowbank in question was created by a plow clearing a parking lot, so it would have been well-packed. The chiseled appearance of the tunnel’s interior suggests the snow was hard. So does the fact that digging a tunnel roughly the width and height of an adult male took Golderberger & Co. eight to 10 hours. It’s also a good sign that the snow appears clean, Washer says. There is no sign of gravel, salt, or dirt, all of which would undermine the integrity of the snow. Dirt, especially, traps heat and attracts light (white snow reflects it), bumping up the risk of melting.
None of this cautious approval in any way suggests that digging your own tunnel is a smart idea. Snow structures are by their very nature temporary. Rain or additional snow---which just keeps coming---would weaken the tunnel by increasing the load it carries. So would air traveling through it. And while Mother Nature’s keeping up the deep freeze, Kassabian says it wouldn’t take much sunshine to start melting the top of the structure, where the snow is least densely packed. In terms of durability, the whole thing is “on the edge.”
So yes, the passageway would likely have lasted a few more days. But that doesn’t erase the concerning overlap between using a homemade tunnel and willingly hopping into an icy crypt.
