22 replies
8h59m
One of my biggest complains for American cities is the risk adversity with respect to trees.
In SF, the city went in a rampage to prune and tear down trees (mostly ficus) because of the risk of the branches falling. There are lots of rules for where you can and can't plant trees based on road visibility, signage, electric cables etc. Result is that you have a lot of tree-less spaces in a city where basically anything grows.
In contrast, Mexico City has an almost anarchist version of urban greenery. Trees overflow streets and side walks. Yes, there are issues from dealing with the urban greenery, but the city is incredibly pleasant to walk in. Also, despite being an incredibly noisy city, trees and buildings mute out a lot of the noise.
For an opposing view, look at what happened during the freeze in Austin, Texas for an example of policies that allow for minimal tree pruning.
It was a significant issue that caused the city an incredible amount of damage. Electric was shut down for days, cars were destroyed, houses had trees fall on them, etc.
Might still be worth it, but an interesting data point nonetheless.
Albeit being a valid datapoint, the conclusion could as well be that it might be better to put electric power down in the ground, get better insurance, don't park under a tree, and so on…
Root penetration of buried services is a serious problem. While roots generally chase water, they will surround and crush any services which get in the way.
Trenching and conduiting is also a lot more expensive. Which is to say: you're looking at a huge amount of cost for what could be described as a very marginal gain because it's already a city.
This is a non-issue in all of Europe maybe apart from south, even poor countries can afford this and root damage is negligent. Its not a serious-enough problem to change your city planning around.
Chances are they did it decades ago when labor was far cheaper and continued to expand the system the entire time.
Tell you what, you enjoy your Mumbai style wire canopy, I'll pay more to live in a place where they bury the lines and tree branches and sky are the only things over my head.
Mumbai has mostly underground utilities, only broadband lines tend to be strung from building to building.
Root penetration is a minimal problem in most cases, sure it does break things sometimes but its probably not as bad as you're making out.
Walkable green streets are not a marginal gain in my book. It is time we make our cities pleasant to live in.
This is the standard for many cities in the northeast. Power lines are underground.
I’ve only seen it done for suburban tract development, never retrofitted to an existing large city. Do you have examples that aren’t a suburban tract? Just curious how it was implemented as the expenses are usually quoted to be astronomical
Center City Philadelphia has a series of squares fro green space and they are laid out in such a way that one can chart a course through the squares to navigate on foot.
Kind of an odd flex given how walkable San Francisco is, but the "risk adversity" is because people actually die. Last year, five people died from fallen trees in a single storm (two in the city).
Mexico City is one of the largest cities in the world. Five people out of 21 million is nothing. Sure, every death is tragic, but there are a lot more efficient ways to spend time and money preventing deaths than tree trimming.
Five deaths in the Bay Area from one storm, two in San Francisco (with a population around 800,000). There were other tree related deaths last year. More to the point, the trees that the city is actively removing are old, mature ficus trees that present a variety of risks (e.g. sidewalks, sewer and other underground utilities), overhead (e.g. public transit) wires.
Too bad ficus are easily the densest canopy tree I’ve seen in california
On the other hand, trees cool down the area so having lot of them should lead to fewer heat-strokes. Last week we hit 95F in my area and I wouldn't be able to walk my dog if not for the trees.
Is not an easy decision. Politicians can be sued if a branch falls over somebody, but can get rid easily of the ten thousands of kills a year by contamination on air and water. Of course somebody being crushed by a tree is a real tragedy, but if the same people would have a heart attack because nitrogen emissions are out of the charts, or they get ill by asthma and can't work, would not reach the news.
An interesting question is: Have people trees because is rich, or they are richer because they had trees? (and this will save a lot of money each year on energy bills, food and even psychologists). Trees are a tool to fight poverty. The problem is how to made the poor people respect them.
Streetview shows this very nicely for Mexico City. I wonder if having so many trees in the city would make chopping down of few trees for some new public development less frowned upon by residents?
Thanks, now I just spent two hours streetview surfing through Mexico City.
"You cannot see the wood for trees"
I'd argue there is so much good that the tradeoff of trees killing a few humans is worth it.
The biological diversity that returns - birds, carbon soil. The air quality. Less chance that the heat will kill our senior citizens. Trees prevent floods.
From NotJustBikes channel, trees and bushes can be used to obscure road visibility, which naturally forces drivers to slow down at a curve, which makes streets safer for pedestrians (43k deaths a year in USA from cars)
In Australia power companies will butcher any tree that gets close to overhead powerlines. Understandable, but result is an ugly streetscape and very little opportunity for green spaces outside parks.