Dude Where Are My Cars: Tacoma Narrows Bridge

Tolls on the Tacoma Narrows bridge are falling short.
This post is 10 in the series: Dude, Where Are My Cars?

Interesting:  tolling revenues on the Tacoma Narrows Bridge are starting to seriously lag behind the official projections.

Source: WSDOT and USEIA

Of course, the blue bars on the chart shows toll revenues, not traffic volumes.  Unfortunately, the state hasn’t reported traffic counts in a while. And since revenues don’t always move in lock step with traffic counts (because tolling rates vary depending on vehicle size and payment method), I can only assume that traffic volumes are also falling short of projections.

Mostly, I attribute the shortfall to gas prices:  when fuel costs shot up, tolling revenues started a year-over-year decline. But the  projections themselves ought to shoulder part of the blame. The state forecast a 3.6 percent year-over-year increase in traffic volumes across the bridge in FY 2011. But statewide, traffic growth over the last decade has been just a fraction of that; and in the past year, the US Dept. of Transportation says that total traffic volumes in the state have actually slipped.

To me, this is just one more piece of evidence that the traffic models that we rely on to forecast our future transportation needs just aren’t cutting the mustard. They always seem to predict that traffic volumes are going to rise, fast, starting today—while the reality for the last decade has been a mixture of slow growth and unexpected dips.

Update 2:05: Fourth-quarter revenues could take a further hit after a glitch in the tolling system issued 26,000 questionable fines.

Sources:  WSDOT and EIA. Hat tip to Joe Cortright.

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  1. Georgie Bright Kunkel says:

    Be informed. I am not a dude.

  2. Clark Williams-Derry says:

    No, Georgie, you are not a dude. But for those who haven’t heard of it, Dude, Where’s My Car is the title of a dopey movie — one that I enjoyed way more than I should have.

  3. Spencer Reeder says:

    Hi Clark,

    Couple things to fold into this particular equation. The debilitating road construction at the I-5/Hwy 16 exit-interchange could have discouraged a lot of folks from the Narrow’s bridge route druring this time (would be interesting to examine ferry traffic to see if there was a corresponding bump, and also to see how the trend corresponds to the recent completion of that project). Q311 isn’t even to the 1/2-way point yet, so not sure if those numbers are pro-rated or not. If not, could account for the big shortfall in that time period.

  4. Spencer Reeder says:

    …although, the construction would have affected the non-toll direction mainly, so any impact on revenue would have been likely attenuated. you’d need the actual traffic volume numbers to really know…

  5. Charles Komanoff says:

    It’s near impossible to evaluate, or, more importantly, quantify the reasonable supposition that higher gas prices have contributed to reduced driving on the TNB, without having quarterly or annual data on bridge crossing volumes (or, at least, toll revenues). Maybe someone with more brains and time than I can tease that from the graph in the post, but I sure couldn’t.

  6. Al K says:

    Another factor could be the huge number of Baby Boomers who are retiring at this time. A lot of us moved to the Kitsap Peninsula in the seventies and eighties and no longer need to commute to jobs in Piece and King counties. Our replacements most likely live on the East side of the bridge
    A quick count of family and friends who have retired recently, who live on the West side of the bridge, comes to eleven of us.

    I drive to Tacoma once a week these days and that is only because my boat is in Tacoma.

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