Gardiner "green roof" is a goofy idea

Post by Mike Klassen in


Greening up the Gardiner Expressway. A good way to hide urban planning disasters?

You could hear the laughter coming through the creaky ducts at CityCaucus Tower. I thought our underpaid research staff were playing Call of Duty again and was prepared to make heads roll. When I arrived on the 21st floor Team were crowded around a computer reading the Toronto Star's report that a "green roof" was being proposed for Toronto's Gardiner Expressway.

From the Star's report:

The plan comes from Les Klein, founding principal at Quadrangle Architects and was unveiled this morning at Moses Znaimer's ideaCity, the annual conference of thinkers...

His idea, dubbed the Green Ribbon, calls for the addition of a new level about 8 metres above the highway's elevated section from Dufferin St. to the Don Valley Parkway. Columns would be added to the side to anchor a new level, which would become a linear park stretching for 7 kilometres. The estimated costs range from $500 million to $600 million.

I forgave the young scamps for their outburst. I smiled myself at the thought of Klein's green ribbon, and wondered how far must cities go for their zeal for accommodating cars?

I checked the calendar to make sure it wasn't April 1st and this was a put-on. Considering how long many in the city have been advocating for improved access to the waterfront, it seemed like an insult. Lots of North American cities have got great hulking freeways cutting through their heart. Tossing some dirt and plants above them hardly looks like a sustainable way to improve your downtown.

This just looks like more of the Symbolic Environmental Movement (SEM) coined by my colleague Daniel. Granted removing the Gardiner presents a whole new set of challenges, but Torontonians should stick to their guns and plan for a downtown that someday doesn't have an overhead freeway.


hi from nyc's high line park. nobody laughed when 10 years ago it was proposed to build a similar project. however the toronto one seems to be way way ambitious. here in nyc it took a lot of hurdles and tons of very well connected people to pull it off. here's a video and review of the the high line park in nyc.

It is a curious idea and might actually be a good one. In Montreal, where the city has quite a bit of elevated freeway, The Metropolitan (North), The Decarie expressway Spagetti (South to Champlain Bridge), these freeways are disintegrating as I write, from all the salt they use in the winter. There have already been a number of newsworthy incidents where people have died or been injured by falling slabs of concrete. If you drive around Montreal, many of these elevated roads are effectively diapered with steel mesh to prevent further incidents.

Covering bridges was done at one time and I would guess had to do with not having to clear snow from the below roads, nor salt said roads. When factored into the suggestion in question, would generate significant savings.

The other big cost would be roof replacement of what is called an upside -down and/or green roof. There is excellent news in this area as well. This study reports on a roof done in Germany in 1920. It is still functioning today with 1920's roofing technology, which expected a regular flat roof to last 10-25 years. Clearly an increase of at least 4 fold.

So if this type of roof were used today, with flat roofs lasting 55 years plus with today's technology, 220 years until the next roof replacement might actually be achievable.

In the end, I wonder how much a roof would decrease overall lifetime operating costs?

Current flat roofing

I admit this looks pretty cool. Maybe there is a way that the Gardiner can achieve this, but the scale is much different. It looks like this example is relatively short, and no longer holds existing traffic above or within it. That said, it looks like a welcome piece of public space.

How about purple or any other color? Why it has to be green? Nice article and very informative.

Some really cool pics of NYC's High Line Park can be found here.
This was a great way to re-purpose some unused urban space. What makes it work is the density surrounding the park. I'm not sure the same can be said for the Gardiner Expressway.

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