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So people like to have trees growing next to the road, on the pavement.
Unfortunately, when some nice species of tree get to a certain size, they tend to produce horizontally growing roots big enough to damage the nearby pavement - and sometimes the road, too. This results in raised or displaced bricks
or pavers, and ridges in tarmacadam.
I propose that such trees be surrounded by rings of sacrificial supports. These would need to be capable of supporting load from above, but not so much from the sides or below. I'm thinking some kind of upturned pottery jars may suit (but if this material doesn't have the appropriate characteristics, others may substitute).
Then when the tree roots expand they will impinge on these pots, which will yield space as necessary and preserve the surface above.
||When do you get to the good bit, with the chainsaw ?
||I was starting to wonder if maybe putting rigid foam
insulation under a sidewalk might work for this.
Then I considered that this might cause more icing
problems in the winter. It seems that most
implementations of this idea would tend to insulate
the sidewalk from the ground, making winter icing
much worse. [+] anyway.
||As soon as the plant breaks the pot, won't the weight deform the ground anyway? The pot would have to support the weight while being broken.
||// The pot would have to support the weight while being broken.//
||Yes. I think the important thing is that it breaks in small increments rather than shatter suddenly and completely into fragments. A pot design with crack guides (lines of weakness or holes), or perhaps tapering wall thickness might help. Some experimentation with different pot designs would be necessary.
||I believe the use of chalk clay liners would be adequate.
Roots cannot penetrate through layers of soil with certain
properties, and a deep baked tube of calcium rich soil
would be portable and produce a boundary layer that, if
left un disturbed, would stop stop root growth for decades
while being natural and eventually leaving the soil in a
otherwise usable state. The installation would have to be
carried out with some care however, as roots would find
any aperture eventually. I suspect that an even greater
problem in urban areas is the havoc that roots can cause in
sewer and drainage infrastructure.