Canadian Consulting Engineer

READERS RESPOND – on Concrete Road Paving, and Mandatory Green Roofs

Following are responses received to articles posted on Canadian Consulting Engineer's Headline News and in the...

January 11, 2010   Canadian Consulting Engineer

Following are responses received to articles posted on Canadian Consulting Engineer’s Headline News and in the print December issue. 

Re.  Concrete paving for municipal roads could be affordable,” CCE Headline News, December 7, 2009.   Click here  to read original story.

The article which appeared on December 7 was written based on a talk I gave at Construct Canada. I was disappointed to read a number of inaccurate/incomplete facts and misquotes throughout the article.

When considering all highways in Ontario (not including municipal streets and local roads) 428.4 lane kilometres (1.95%) are paved in concrete [for example: highways 407, 401, 410, 417, 427] and 1,166 lane kilometres (5.30%) are composite pavements [for example highway 401 through Toronto]. There are also a number of municipal streets and roads paved with concrete. The concrete industry is hoping that concrete paving will be used more in municipal streets and local roads once the long-term value and cost savings are realized.

Most engineers think concrete will initially cost significantly more than asphalt, but the tool will show that this is not always the case. And while it is well known already that concrete will provide a good payback over its lifecycle, the CANPav program will show that concrete is often more economical than asphalt even at a first cost basis.

The economical benefits of concrete include its reduced repair and maintenance. Typically, when considering a 50 year analysis period (Reference: MTO MERO-18), asphalt pavement requires joint routing/resealing at 3 years and the first resurfacing at 19 years. With concrete pavement, the expected structural life is much higher, with the first resurfacing at 28 years. However, a number of municipalities have reported concrete roads still in use after 50 years with minimal maintenance.

The environmental benefits of concrete include being a cool pavement (lowering the urban heat island effect), reducing truck and car fuel consumption (lowering green house gas emissions), and requiring less aggregate for the base (saving in materials and trucking).

Another advantage is concrete reflectance (high albedo), which can save owners up to 30% in lighting costs. Even utility cuts and repairs are not problematic; they can be easily completed to bring the pavement back to its original condition.

Also, a number of pervious concrete parking lots have been constructed in Ontario over the past three years, including an on-street parking lay-by in the City of Mississauga and a commuter parking lot by the MTO. There are approximately eight projects expected to be tendered for 2010 across Ontario. The CANPav online is free, at www.canpav.com

Sherry Sutherland, MASc, P.Eng, LEED AP, Technical Engineer, Ready Mixed Concrete Association of Ontario (RMCAO), Toronto. 

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Re. Comment, “Should Green Roofs Be Mandatory?” Print edition, December 2009, page 4.  Click here to see original article.

GreenRoofs

As a long-time reader of  Canadian Consulting Engineer and an engineer, I was a bit miffed by the editorial – “Should Green Roofs Be Mandatory” in such a respected magazine whose purpose is to cover innovative engineering projects, news and business information for professional engineers.

It has been my experience that editorials are generally related to the content of each issue but other than the nagging questions that are in the editorial I did not find any news or business information for professional engineers related to the main thrust of the editorial. At the very least I would have expected the magazine to point to the information available at the City of Toronto website (www.toronto.ca/greenroofs) and also the information available for engineers at the Ontario Society of Professional Engineers website (http://www.ospe.on.ca/news_09Sept22.html ).

The thing that it seems is missing from the editorial is that a magazine that is to cover the innovations of engineers failed to recognize the leadership and innovation of the engineers that have been involved in the development of engineered green roof systems. There is no doubt that there is learning that needs to happen. There is no doubt that there are some legitimate concerns. But which innovative idea is without questions and concerns. An editorial in such a respectable engineering magazine needs to provide a voice for these concerns to be discussed and resolved.

I would be happy to write an article for Canadian Consulting Engineer in a future issue. Both as an engineer and a person closely involved with green roofs I feel that your readers deserve that courtesy.

Hitesh Doshi, P. Eng., Professor, Department of Architectural Science, Faculty of Engineering, Architecture and Science, Toronto


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