February 11, 2014

Dude, Where are my Toll-Paying Cars? – 2: Wishful thinking on the Port Mann

What do the revised Port Mann revenue forecasts mean for traffic?  Clark Williams-Derry at the Sightline Institute compares past and current projections:


Port Mann - projection


The province is still forecasting that Port Mann traffic will start soaring any day now.

Traffic is assumed to grow in step with reported revenue projections, after adjusting for inflation in toll rates.

Possible sources of error:

  • Inflation: Tolls are supposed to rise with inflation, capped at 2.5%. But I don’t know what inflation forecast they used. I assumed 2%.
  • Other revenue: It may not account for all revenue sources (e.g., enforcement, pay-by-camera charges)
  • Limited data for recent trends: I estimated 2013 and 2014 Port Mann traffic from January data only


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  1. The toll IS, however, having one of its intended effects – to discourage use of the Port Mann bridge for “traffic demand management” purposes. – so that the traffic volume doesn’t immediately inflate to fit the added capacity provided (you know, that traffic increases to fill the extra lanes).

    As an aside, New Westminster refused to approve road improvements on the North side of the Fraser – the North Fraser Perimeter Road (not a new road, but improvements to the existing roads) that would have helped deal with truck traffic. Remember, Gateway was a system of 3 roadways – Port Mann Highway 1, South Fraser Perimeter Road and North Fraser Perimeter Road. For NFPR, only the Pitt River Bridge portion was built and New Westminster stonewalled the rest (and now it’s complaining). So what was built is an incomplete system.

    1. That’s true – I think Coquitlam even offered to pay New West’s share for the replacement of the United Blvd Brunette bailey bridge.

      1. Hey, New West is coming around. They now agree that it would be ok to replace the one lane bridge with a one lane bridge! What a comprimise!

        And then they say run the new Putello to Coquitlam. In the spirit of comprimise, as a Coquitlam resident, I agree. However, I expect New West to pay for the bridge and Coquitlam to receive all the tolls. I guarantee traffic volumes in New West will go way down!

  2. A graph, over a short period of time, showing one part of a system that has had a price increase while the others have not, knowing full well that traffic has shifted (sometime dramatically) to other options is incompetant at best and outright deceitful at most.

    There’s compelling arguments to be had without resorting to manipulating data.

    1. Ron, I’m curious what you consider ‘manipulated data’ in the chart above? From what I can figure out, the historical line comes from publicly available Provincial data sources and the dotted lines represent government forecasts (either published or estimated, with assumptions documented). Not much manipulation in my eyes, simply a statement of what has happened and what is forecast to happen, no matter how incredulous looking.

      Not much question that some traffic diverted to Patullo and others….but (a) the PMB toll came into effect in 2012, well after traffic peaked in 2006, and (b) shouldn’t that price increase to PMB be more obvious in the forecast? Last I checked, increased tolls generally drive traffic down, not up….precisely your comment related to shifting traffic trends. If that’s the case, you should be more concerned with the viability of the forecast than how it’s displayed.