Toll-booth-free tolling on SR 520 and I-90

As early as 2010, the east-west transportation corridor could see a return to the pay-as-you-go model, done without the slowdown of a toll booth.
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Traffic on the SR 520 bridge

As early as 2010, the east-west transportation corridor could see a return to the pay-as-you-go model, done without the slowdown of a toll booth.

The State Route 520 Tolling Implementation Committee's "November Scenario Evaluation" document (pdf) released last week shows that the most robust regional financing for replacing the dangerously sub-par 520 bridge comes from time-variable tolling starting in 2010 and tolling the parallel I-90 span across Lake Washington, starting in 2010 or 2016. Tolling in this key east-west corridor would be done on the fly, electronically, with vehicle windshield transponders and overhead gantries — no toll booths. Tolls that vary by time of day are likely, though flat rates are also an option. Special lanes that would be free to buses and ride-sharers could be made available to solo drivers, for a price.

The committee's members are WSDOT Secretary Paula Hammond, Puget Sound Regional Council Executive Director Bob Drewel, and Washington State Transportation Commission board member Richard Ford. This latest analysis, along with public comment, will inform a January 2009 final report from the committee to the state legislature, which is then to approve a tolling plan for the SR 520 bridge and perhaps the I-90 bridge as well. Then, specific toll rates would be set by the state transportation commission and approved by the legislature, with construction of pontoons for the new 520 bridge beginning later in 2009 if all goes as envisioned.

The weary and crowded 1963-vintage 520 bridge connects Seattle with Eastside job centers such as Bellevue, Redmond, and Kirkland but is at major risk of catastrophic failure in a 70 mph windstorm, or earthquake. At the same time, growing regional traffic congestion has prompted a public warming to expansion of regional transit, and bettered the odds for a system of electronic, time-variable tolling on major highways and state routes across metro Puget Sound. A priced-lanes pilot project for carpoolers and solo drivers is already underway on SR 167, and flat-rate electronic tolling in place, to rave reviews, on the new southbound span of the Tacoma Narrows Bridge.

The 520 tolling committee's latest report reveals that:

  • Starting tolling in 2010 instead of at bridge completion in 2016 would pry loose an additional $400-$500 million, lowering the costs of bond borrowing for construction, which is to be repaid by tolls;
  • The most revenue toward completion of the $3.7 to $3.9 billion project comes from tolling both the SR 520 and I-90 bridges starting in 2010 ($2.4 billion, Scenario No. 9) or 520 in 2010 and I-90 in 2016 ($2.4 billion, Scenario No. 4);
  • One-way tolls on both bridges would range from 75 cents off-peak to $2.95 at peak hours in Scenario No. 9, and from 75 cents off-peak to $3.25 at peak in Scenario No. 4;
  • Tolling 520 alone starting in 2010 (Scenario No. 7) would cut peak-hour traffic volume in the vicinity of 17 to 26 percent while peak-hour flow would rise three to seven percent on I-90;
  • Tolling both 520 and I-90 starting in 2016 (Scenario No. 9) would deliver peak-hour volume cuts of 10 to 11 percent on 520 and 12-16 percent on I-90, as commuters shift travel times or use transit;
  • Time-variable tolling increases peak-hour speeds on 520 by 13-16 mph, nearly double the speed gain from flat toll rates.
  • Tolling opponents somehow imagine they are due a free ride because the construction, maintenance, and operations costs of Puget Sound roads and bridges, as population continues to swell in coming decades, can somehow all be covered by the incredible shrinking gas tax and ... what? More sales tax hikes or vehicle fees? They're nice if you can get 'em, but the well only runs so deep.

    Pay as you go is the way to go in this day and age — coupled with cost-saving, performance-based consortium contracting to design, build, operate, and maintain surface transportation facilities and systems.

    The four-lane SR 520 bridge across the lake is to be replaced with a six-lane structure. Current plans call for two "general purpose" lanes and one high-occupancy vehicle lane in each direction, the former would be tolled via either a flat or time-variable rate if a plan is adopted. This is confirmed by WSDOT, though it can get a bit confusing because one doesn't necessarily think of general purpose lanes as being tolled. On the I-90 bridge, the agency also confirms, tolling would be on all general purpose vehicle lanes, except under one scenario that exempts eastbound traffic from Mercer Island. On both bridges the possible HOV lane could be designated a High Occupancy and Toll (HOT lane), free to transit and ride-share vehicles, but also available, for a toll, to solo drivers.

    The more time-variable tolling, and the sooner, the better: It will further drive alternative choices such as ride-sharing and telework, and raise more money for regional surface transportation needs, transit included.

    The policy decisions to come on tolling the SR 520 bridge, and perhaps the I-90 bridge as well, are an important turning point for the state and region. Going forward, a broad regional plan to implement time-variable tolling on several highways and major state routes is needed. That would allocate scarce peak-hour capacity, ease congestion, and help pay for billions more in needed safety, repair, and mobility improvements on I-5, SR 99, SR 704, SR 509, US 2 and I-405/SR 167.

    The question is, how serious are we about doing this? The legislature will provide the first piece of the answer when it next meets.

    Editor's Note: This article first appeared at Cascadia Prospectus.  

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