Silo Mentality: Getting to the Root of the Problem

Digging up Toronto’s buried bridges is an idea that seems both romantic and uncontrollably appealing to me. Preferably, it would be done by hand. Perhaps 50 people, with shovels, taking breaks for lemonade. The buried Harbord bridge at Grace (still marked with a concrete railing) would be a good place to start. Or the Crawford bridge. We wouldn’t have to dig up the whole thing – even just revealing a single arch would be worth the effort.

Bridges are beautiful. As a metaphor, they represent our collective determination to overcome obstacles and connect us all together. (I suppose they equally represent laziness too – why not go around? – and our controlling tendency to tame the texture of the landscape to accommodate our needs.) Aesthetically, bridges are comprised of attractive organic shapes like the arch of a stretched spine.

But before we start sharpening our shovels, we have small problem to solve. If we were to dig out the ravines at Crawford or Harbord, we’d have to kill a lot of pretty trees in the process. I have at least two arbourist friends who would be very unhappy about this. But worry not, colleagues.  I have invented the “tree silo”. It’s quite simple really. Tree silos are vertical cylindrical pillars full of soil. They allow trees to stay alive, even if the land surrounding the tree is suddenly lowered 40 feet by lemonade-drinking romantics.

Now, you may be thinking: “That wouldn’t work. A tree’s root system is quite wide, and would never fit into the silo. Even if you did fit the roots in, the tree would have no vertical strength and would fall over.” To you I say: let your pessimism drop away, like autumn leaves. Surely if we can walk on the moon, then we can find a way to liberate trees from their obsessive attachment to wide horizontal root structures (fig 1, top image). Besides, aren’t there trees growing out of little concrete boxes all over town? Sure, these park trees are much bigger…. but I’m confident that we can do it.

As we look for solutions, I would suggest a few directions for which to inspire your thoughts. First, we might need to develop a ‘root bending’ process (fig 2, top) that would most likely involve steam baths. Secondly, we’ll definitely need to develop ‘root braces’ not unlike a plaster cast that we might put on my or your leg – except a root brace would be made of a futuristic woven steel fabric (WSF) that allows the root to breathe, absorb water and grow.

At this point, you may ask: “Why not just dig out the trees and transplant them in the ravine, post-dig?” While this approach would save a lot of time and money, I’m worried that the trees would go into shock from the sudden change of sunlight patterns. They would get much less exposure down in the ravine, and they might die from sadness. Perched up on a tree silo, they’ll be happy (fig 3, top).

There is little doubt that Toronto would benefit greatly from revealing her lost rivers and buried bridges. As we embark on a journey of subterranean discovery and exhumation, I hope that tree silos can become a helpful part of this urban archeological endeavor.

Additional resources:
Toronto Lost Rivers
Human River walk

Garrison Creek (WikiPedia)

Garrison Creek walking map (PDF)


3 responses to “Silo Mentality: Getting to the Root of the Problem

  1. I have temporairly suspended my earlier pessimism. But of course, tree silos! Although I recommend the lemonade romantics wear helmets to protect themselves from falling nuts.

  2. How much soil is there on top of the bridge? What if we transplanted the trees on top of the bridge, rather than down in the ravine? That would keep help cars off the bridge anyway, while pedestrians and cyclists could pass through.

    A forest on a bridge sounds rather lemonade-romantic too, no?

  3. The only problem is that its not the depth of the tree roots that is the thing to consider. Roots at the surface are the primary concern.

    Really, all you want to do is save the trees. So building the silos out of wood around them during excavation and then dig a whole beneath it and eventually “lower” into into the new hole.

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