Stephen Rees's blog

Thoughts about the relationships between transport and the urban area it serves

Port Mann twinning myths

with 4 comments

This is over at the LRC web site – but the link to the Burnaby News Leader letters page does not work and the letter itself is no longer there. But then very few letters are there, and the way the Black Press portal is set up seems to defy its use as an archive. But perhaps that is deliberate – so I make no apology for duplicating it – not because I endorse it but I think views like this need to be widely disseminated

Port Mann twinning myths

At the core of our transportation system is the Trans-Canada Highway which spans this great nation of ours.

In B.C. the Port Mann Bridge and Highway 1 connects Vancouver, Burnaby, New Westminster and Coquitlam with Surrey, Langley and the rest of Canada.

The curved Port Mann Bridge cost five times more per lineal foot (30.5 cm) than a straight bridge, which I learnt as an engineering student in 1979.

“On June 12, 1964 The Port Mann Bridge opened. Its construction was unique in North America, and at the time it was the most expensive piece of highway in Canada,” according to vancouverhistory.ca/chronology1964.htm

Since no other authority in North America can afford to build a curved bridge, why would B.C. twin the curved Port Mann Bridge if B.C. knew that the cost was going to be at least five times more than a straight bridge?

If you were an investor, say in a company that was going to bid on the contract that would make you many times richer wouldn’t you want to build it?

In 1964, investors got B.C. taxpayers to make them many times richer by building the curved Port Mann Bridge. Engineers got the opportunity and higher pay to design and build a curved bridge which no other province or country could afford.

When you design for profit of the wealthy, taxpayer money is easy to find, even if the project is obviously not going to solve any traffic or environmental problems.

Why would B.C. twin the Port Mann Bridge when B.C. won’t pay for seismic upgrading?

“In 1994, Buckland & Taylor Ltd., in conjunction with Geomatrix Inc. of San Francisco and MacLeod Geotechnical of North Vancouver, performed a seismic evaluation and prepared recommendations for the bridge retrofit. This work included:

  • Liquefaction and ground movement assessment;
  • Dynamic testing of the main span and south approach span;
  • Dynamic analysis for multiple earthquake time histories;
  • Push-over analysis for typical concrete bents;
  • Preparation of retrofit recommendations.

“In 2001, the Company completed the design and preparation of tender documents. Due to budget restraints, the construction of the retrofit has been put on hold by the Owner, according to b-t.com/projects/portmann.htm “

You get what you vote for? For a real solution look at the Sydney Harbour Bridge in Australia built in 1926 (nine years before the Pattullo Bridge) with 12-16 lanes, and designed to last 1,000 years. The Sydney Bridge reached nearly 90 per cent of maximum capacity in the late 1980s due to good planning for transportation and the environment.

In B.C. we’re still doing it wrong. Three billion dollars to twin the Port Mann Bridge is equal to building 32.7 fast ferries, based on a cost of $275 million for three ferries.

Think the Pattullo Bridge is safe? Drive under the Surrey side supports and look up at the two feet of steel shims propping the bridge up.

What’s happening to B.C.?

G. Pettipas
New Westminster

Just to nitpick a bit, the bridge main span itself is not curved – it is the approaches that curve. And the province’s neglect of seismic upgrading of major bridges is widespread and not just confined to this one. The bridges handed over to Translink (Knight Street, Patullo and Westham Island) were all badly in need of retrofitting after years of neglect. And as we saw in Montreal and Minnesota this is not an attitude unique to BC.

Secondly, I am not sure the Sydney Harbour Bridge is evidence of “good planning for transportation and the environment”. As the author himself points out the capacity was not adequate for the design life, and the suburbs of Sydney sprawl over huge distances. Note too he counts the traffic lanes and not the electric train tracks. Australian cities tend to have much better rapid transit systems than equivalent Canadian cities (see Newmann and Kenworthy).

Thirdly, are not the “steel shims” on the Patullo evidence that something has at least now been done to “prop the bridge up” – by Translink, who could ill afford it, unlike the province which could but didn’t, preferring to give its friends tax breaks and pay off the debt.

Written by Stephen Rees

August 25, 2007 at 10:32 am

Posted in Transportation

4 Responses

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  1. Lions Gate bridge was seismicly upgraded at the time of the deck replacement. The north piers are no physically anchored to the foundations. The bases of the piers are slotted into housings that allow the feet of the piers to move in an earthquake. Quite scary to see (or think about). http://www.b-t.com/projects/liongate.htm

    Second Narrows Bridge was upgraded in 1994 (when it was repaved, etc.)
    http://www.b-t.com/projects/snb.htm

    And the Massey Tunnel’s seismic retrofit was completed in Dec 2006. Otherwise the precast tunnel segments sitting on te river bed could have shifted and water would have just gushed in. http://www.b-t.com/projects/massey.htm

    ron c.

    August 27, 2007 at 5:26 pm

  2. Here’s a link with a pic of the Lions Gate Bridge north viaduct footings.

    http://www.construction.com/NewsCenter/Headlines/ENR/20020128b.asp

    “The north approach viaduct also received what engineers claim is the world’s first design-build seismic retrofit. Klohn-Crippen Consultants Ltd., Vancouver, decided on a plan to allow 24 steel bents to rock on their concrete pedestals. “We’d been joking about taking the nuts off the anchor bolts so the foundations could just lift off at the base plates,” says Bruce Hamersley, Klohn-Crippen project manager. But after research was done, it became reality. “Fifty bucks to take the nuts off, $2 million to prove it worked, and we’re done,” he says facetiously. The approximately $3-million retrofit of the steel structure is designed for a 1-in-475-year likelihood seismic event.”

    ron c.

    August 27, 2007 at 5:32 pm

  3. Why is a curved bridge 5 times the cost of a straight bridge? That cannot be correct.

    Perhaps 1.5x the cost of a straight bridge is more like it.

    Mark

    Mark Smith

    February 3, 2010 at 3:47 pm

  4. I hear they are going to scrap the Port Mann now… Has anyone concidered it could be dismantled – moved down river and erected to replace the Patullo?

    Just a thought. After all it is paid for.

    RBushby

    October 20, 2010 at 4:46 pm


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