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Prospectus Blog Gregoire Advisor: Tunnel “Probably Most Viable Option” To Replace Seattle’s Alaskan Way Viaduct

Washington Governor Chris Gregoire yesterday announced she’d push back by two weeks a recommendation on how to best replace the aging, earthquake-prone Alaskan Way Viaduct on State Route 99 along Seattle’s downtown waterfront. But there’s more. A top Gregoire advisor tells the Seattle Times that the deep bored tunnel proposal – energetically advanced by Viaduct Stakeholders Advisory Committee members plus our Cascadia Center and the general public – is “probably the most viable option.” Deep bore tunneling technology has advanced greatly in recent years and the method is considered highly suitable for an inland downtown tunnel away from Seattle’s waterfront. (A tunnel boring machine used for Madrid’s M30 roadway project is pictured below, right.) The Times:

OLYMPIA – A proposed tunnel to replace the Alaskan Way Viaduct is making a comeback. A key adviser to Gov. Christine Gregoire said Tuesday that replacing the viaduct with a deep-bored tunnel “is probably the most viable option” – if the numbers pencil out. The comments came after Gregoire, King County Executive Ron Sims and Seattle Mayor Greg Nickels issued a joint statement saying they would miss today’s deadline for deciding how to replace the viaduct and needed more time to study the options. They now expect to make a decision sometime in January, according to the Governor’s Office. The reason for the delay? “The interest in the tunnel has led us to take some additional time to study it right,” said Ron Judd, a senior adviser to the governor and her lead negotiator on the viaduct…..
Judd said transportation planners will be crunching numbers and talking to international tunnel experts to see if a tunnel is feasible now. “I think the governor would say that if we could make the numbers work, that is probably the most viable option,” Judd said. “But that option is going to mean that there has to be a real meaningful partnership with the city and county and Port [of Seattle] to make it happen.”

Gov. Gregoire’s administration, the Washington Department of Transportation, the project team and SAC members are all to be commended for pursuing an optimal solution for the region and the economy which includes a deep-bored, inland, downtown bypass tunnel on SR 99.
A useful template for the detailed discussions which will continue next week is the state’s own breakdown of the costs for either a twin-bored or single-bored tunnel. This WSDOT slide briefing presented to the Puget Sound Regional Council, SAC members and other interested parties on Dec. 16 shows:

  • A single bored, dual level tunnel could be 54 feet in diameter, with two 12-foot lanes in each direction, and an eight-foot and four-foot shoulder in each direction (see the 9th slide in the above link, they are not numbered).
  • Tunnel components are defined as work on city streets and at entrance ramps, construction of south and north portals, construction of the tunnel, utilities work at portals, and tunnel systems. Broader “scenario components” for the tunnel include downtown seawall replacement, an Alaskan Way and Western Avenue “couplet” boulevard system, waterfront utilities, surface street improvements, Viaduct removal, transit enhancements, and Interstate 5 improvements (13th slide).
  • “Tunnel only” costs for building a (two mile long) twin bore tunnel would be $1.24 billion, versus $961 million for the above described single bore version; (14th slide);
  • Those estimates grow to $2.82 billion and $2.13 billion, respectively, when WSDOT factors in contract and construction management, administration, preliminary and final design, contingency risk, and potential cost escalation (15th slide).
  • Addition of the above-described “scenario components” raises the figures to $3.5 billion for a double-bore tunnel and $2.8 billion for a single-bore tunnel (15th slide).
  • Adding in another $1.1 billion in already planned “Moving Forward” projects for improvements to SR 99 at the north and south ends of the existing, elevated Viaduct and elsewhere brings the total to $4.6 billion for the double-bored tunnel and $3.9 billion for the double-bored tunnel (15th slide).
  • So, to report that the tunnel is estimated to cost $3.5 billion, or $4.6 billion, leaves out a lot.
    The state has $1.3 to $1.7 billion left to spend on Viaduct replacement at present. However, additional funds can be raised from:

  • a local improvement district funded by property owners whose values rise due to the project;
  • tolling the tunnel (and parallel I-5);
  • and quite possibly from the Port of Seattle and City of Seattle, which both have a vital stake in regional mobility and access.
  • The tunnel-only estimates ($1.2 B for double bored and $961M for single bored) can both be paid for within the current budget.
    Risk factors can be firmly controlled with a stringent competitive bid process tied to innovative “alliance contracting” recommended by the Washington State Transportation Commission. Under this approach, design and construction can be coordinated by a contractor consortium which is paid in full only if strict performance measures are met, including an accelerated construction schedule and project completion deadline.
    In addition, the downward turn in the global economy has resulted in a sharp drop in the cost of construction materials. Contractors are hungrier, as well. This reduces the cost overrun risk, especially if material and labor costs are locked in at something close to current value. Industry-leading professionals could be brought in to manage the project, with pay incentives for cost control.
    Discussions in the coming weeks, before the Governor makes a formal proposal to the legislature for Viaduct replacement, are likely to include not only additional funding and financing strategies, but also cost control strategies, refinements of project scope, and a fleshed-out set of next steps. Many or at least some of the “scenario components” could arguably be left out. Even if not, the single-bore version, with the highest assumed level of administrative, design and risk costs, plus all “scenario components,” is estimated by WSDOT to cost $2.8 billion, against $1.3 to $1.7 billion in current funds.
    As noted above, that gap could absolutely be closed through tolling and a local improvement district, at no added cost to the state. Participants underscored such an approach earlier this month, as reported in The Seattle Times.
    The legislature will make the final decision, during a session in which priorities will also include taming the state budget deficit and authorizing time-variable electronic tolling to help pay for replacement of the unsafe SR 520 floating bridge. You could say the stars are aligned.
    Excitement over the looming federal stimulus package aside, each of the nation’s 50 state governments will be necessarily embracing a “pay as you go” ethic to help ensure high-priority programs and facilities are maintained and built in these trying economic times. In surface transportation especially, the heavy lifting next year and in coming decades will have to be at the regional level.
    In terms of congestion management, jobs stimulus, durability, life-span, seismic safety, air quality, and urban design and environmental amenities, the deep bore tunnel option trumps another elevated viaduct or a massive dumping of traffic on surface streets. A full life cycle cost-benefit analysis is the responsible approach.
    We’ve only got one chance. Let’s get this one right.