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Collection: Seattle's Great Viaduct Debate

Preview: Stuck in a Jam

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Several months ago, I sat down with a few earnest young filmmakers of Undrgrnd Productions, who were eager to discuss one of my own favorite topics: traffic!

Just this morning, Luv, Vijay, and Mahim emailed me the trailer for their film. As they write, “it’s about traffic and transit, but also about related issues like housing, density, the city’s exploding growth, its history, politics, and problems.” Yep—traffic conversations certainly surface all of those other topics as well. The full film will debut in August, but for now, be sure to check out the trailer:

At Least The Tunnel Isn’t Boring

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cc Trevor Dykstra
cc Trevor Dykstra

There are plenty of words to describe the ongoing drama over Seattle’s not-boring tunnel boring fiasco. Ironic, for one, given that the 8-inch pipe that brought the world’s largest tunneling machine to a halt was put in Bertha’s way by none other than the Washington State Department of Transportation, as part of the early feasibility studies for the very tunnel they’re now trying to build. Entertaining, because both WSDOT and Seattle Tunneling Partners, the private group that WSDOT hired to dig the tunnel, are busy pointing fingers at one another, positioning themselves for the inevitable battles in court and in the press. Exasperating, too, since it’s becoming increasingly unlikely that the tunnel will be completed on time, on scope, and on budget.

But unexpected? Not in the least.

Sure, nobody foresaw that Bertha would run aground on this particular well casing, any more than they predicted the machine’s “painfully slow start,” or prophesied the specific labor disputes and technical problems that halted work for four weeks in August and September.

Tunnel cost overruns

Still, anyone who is surprised that a mindbogglingly complex megaproject like the deep bore tunnel could go badly awry simply wasn’t paying attention. As our 2009 report on Seattle-area cost overruns highlighted, three out of four of greater Seattle’s four major tunneling projects went substantially over budget. And while the I-90 tunnel through Mt. Baker came in well under budget, Seattle’s experience suggests that tunnel troubles are the rule, not the exception.

But it’s not just Seattle. Oxford University researcher Bent Flyvbjerg has documented a worldwide tendency for megaprojects to go over budget.

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Alaskan Way Viaduct: More Revenue Shortfalls Expected

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This should come as a surprise to precisely nobody—and yet there’s still something shocking about this article from Mike Lindblom at The Seattle Times:

More than three years after state lawmakers approved the Highway 99 tunnel, officials have yet to figure out how they can collect tolls for construction without clogging Seattle streets…One scenario, with tolls from $1 off-peak to $3.25 peak each direction, would raise $200 million for construction but divert one-third to half the daily traffic, said an official with access to the details… “It really is important to all of us we not cause diversion,” [House Transportation Committee chair Judy] Clibborn said. “I have been out telling everyone to count less on money that comes from tolling, and think of tolling as a lower amount, that covers operations and maintenance.”

Back in February, the state announced that it was cutting its tolling revenue forecast by half, from $400 million to $200 million (see page 9 of this pdf). And now, just a few months later, we’re already being conditioned to see $200 million as an upper bound—with actual revenues potentially falling far lower, meaning that the people who actually drive through the tunnel may prove willing to pay less than 5 percent of the overall cost of replacing the Viaduct.

Yet as we’ve said before, the fact that tolls cause traffic diversion is hardly new news. WSDOT’s own Final Environmental Impact Statement for the tunnel, published last July, said:

Tolling would cause vehicles to divert from SR 99 to other nearby roadways…the bored tunnel is expected to result in a daily diversion rate of about 40 percent for all vehicle classes.

Diverted traffic is something of an open secret: everybody knew about it, but nobody who supported the tunnel wanted to discuss it in public. (We did, but it felt like howling in the wilderness.) But now that the project is moving forward, the chickens are coming home to roost—and the state has to actually figure its way out of the mess it’s created.

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News Flash: Drivers Avoid Tolls

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Seattle Times headline: Tunnel + tolls = traffic trouble.

Seattle Times headline: Tunnel + tolls = traffic trouble.For Seattle traffic-watchers, Mike Lindblom at the Seattle Times has the most important story of the month: the news that a new state traffic study predicts that high rush hour tolls on the Alaskan Way Viaduct tunnel will divert 9,100 cars into downtown Seattle during the afternoon commute. For those of you who are counting, that’s a diversion rate of about 42 percent.

The Times editors considered it a bombshell. It was the day’s top story, above the fold, with a huge headline.

But here’s the thing: it’s not really news. Well, it’s only sort of news. I mean, there really was a new tolling study on the Viaduct, and it really did predict that lots of drivers would avoid the tolls by driving on surface streets. Yet the new study reached almost exactly the same conclusion that WSDOT itself reached last year. Here’s a quote from the transportation technical report appended to WSDOT’s 2011 Final Environmental Impact Statement:

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The Environmental Case Against the Deep-bore Tunnel

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Editor’s Note: This piece was originally posted on Crosscut, and is a rebuttal to an earlier opinion piece on Seattle’s deep-bore tunnel.

Four of our friends and environmental colleagues recently made a case for tunneling under downtown Seattle to replace the Alaskan Way Viaduct. They, along with many of our friends in the labor and business communities, have concluded that the tunnel is the only viable path forward. It pains us to disagree, because we respect them and value the relationships and accomplishments that our work together has brought.

As a citywide vote on the deep-bore tunnel approaches, however, we cannot remain silent. Like many, we are frustrated by the seemingly endless delays and squabbles that have surrounded this issue. We empathize with the cries to “Just do something! Anything!” But we can’t go along with that “anything” when the chosen path—the deep-bore tunnel—is demonstrably inferior to the leading alternative.

The advantages of the package of smart investments called streets/transit/I-5 (“ST5”) are overwhelming. Compared with the tunnel, ST5 creates construction jobs for local workers more quickly, improves traffic flow downtown, yields the same beautiful waterfront, is faster to build, aligns with our civic values and climate goals, and saves us about $1 billion.

The new, 7,351-page Environmental Impact Statement gets us past the claims and counterclaims with a comprehensive analysis that clearly shows the tunnel’s failings. It shows, for example, that the tolled tunnel will put almost as much traffic on the streets of downtown Seattle as would just closing the viaduct and walking away. Repeat: spending billions on a tolled tunnel is barely better for downtown streets than letting the viaduct fall down.

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The Tolled Tunnel: Almost An Earthquake?

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The Final Environmental Impact Statement for the Alaskan Way Viaduct replacement project just came out, and it’s a MASSIVE document: 286 pages in the main report, plus a whopping 23 appendices.  The transportation discipline report (Appendix C) alone runs to 664 pages.  I haven’t actually counted all the pages, but I have to assume that they run into the thousands.

With that much ink devoted to the project, I’m sure that people on all sides of the debate can find tidbits to support their particular point of view.  But the tidbits I’m most interested in center on my current obsession:  what happens when you toll a single link in a big urban transportation network?

To its credit, the EIS does take a look at how tolling could affect traffic flows on city streets. The results?  In a nutshell, the state’s traffic models suggest that, from the perspective of traffic on city streets, the tolled tunnel is only a bit better than an earthquake that closes the Viaduct for good.  Here are some numbers, culled from Appendix C:

Traffic volumes: earthquake vs. tolled tunnel
Source: Viaduct Final EIS, Appendix C.

As you can see, compared with an earthquake that closes the Viaduct, the state says that the tolled bored tunnel would modestly reduce traffic volumes in lower Queen Anne, on streets in the downtown core, and reduce them a bit more in Alaskan Way through Sodo. But the bored tunnel would make traffic a little worse in South Lake Union. And it’s basically the same as an earthquake for the waterfront, First Hill and Capitol Hill, and traffic crossing between Sodo and the ID/Pioneer Square.  (Click on the map to the right for a larger map of where those screenlines are.)

Other parts of the transportation appendix show that the bored tunnel, with tolls, would reduce total traffic delays by about 6 percent in “Seattle’s Center City,” compared with an earthquake. That’s not nothing, but it’s not a lot either.  In fact, in terms of center city traffic delays, the tolled bored tunnel is actually one of the worst performers among the options studied.

Now for the caveats:

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Is The Tunnel Worse Than Nothing?

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A few months back, the transportation consulting firm NelsonNygaard released a fascinating report that looked at what might happen to downtown Seattle traffic patterns if the state builds a tunnel through downtown, while imposing a steep toll on drivers who choose to take it. (We’ve already written about that report once before.)

Below, for your viewing pleasure, is the most important image from that report. Click it to see a larger version — and I’ll explain what it means in a moment.

City and state figures show that a tolled tunnel will snarl downtown traffic, compared with the “Streets, Transit, and I-5” plan.

There’s a lot of information in the chart, but you can ignore much of it.  The only thing I want you to pay attention to are the orange and yellow bars:

  • The dark orange bars represent the state’s projections for 2015 traffic volumes under the most likely deep bore tunnel scenario, in which drivers would pay $5.00 to use the tunnel during the afternoon rush hour.
  • The yellow bars represent traffic volumes under the “ST5” or “Streets, Transit, and I-5” plan, using the same traffic model but with some different inputs.  Under the ST5 plan, the city and state would make substantial investments in transit and “transportation demand management” to reduce traffic volumes, and also make improvements to city streets and I-5 to help improve traffic flows.

The first thing to notice is that the ST5 plan results in lower overall traffic volumes. (Those are the tallest bars to the left; the yellow ST5 bars are lower than the orange tolled tunnel ones.) If you care about greenhouse gas emissions from Seattle’s traffic, this is certainly an important thing to pay attention to.

But the second thing to notice is the length of the orange and yellow bars for center city streets, I-5, and arterials east of I-5.  For all those three corridors, the orange bars are all longer than the yellow bars.  And what that means is simple:  the state’s own traffic models are projecting that a tolled deep-bore tunnel creates worse traffic downtown and on I-5 than the streets-and-transit plan.

It’s simply devastating news for the deep-bore tunnel, because it means that the city and state are predicting that a multi-billion dollar tolled tunnel would actually make downtown gridlock worse.

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Viaduct Diversion, By the Numbers

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I think these may be the most important two sentences from the recent NelsonNygaard report on traffic diversion from Seattle’s Alaskan Way Viaduct:

The State did model the 2015 Program (including the Elliott/Western Connector) with Toll Scenario C, but the results are not included in the SDEIS. In the model forecast including the connector, 38,000 daily trips use the tunnel…[Emphasis added]

AWV cross sectionTranslation:  the state itself says that in the early years, a tolled deep bore tunnel would carry only about a third as much traffic as the existing Viaduct.  The remaining traffic—roughly 72,000 cars and trucks—would be diverted onto I-5 and city streets.

Of course, these figures are based on the state’s transportation models—and I have very few kind things to say about traffic models in general.  Many have proven rigid and unreliable, and none projected the traffic trends we’ve seen in the last few years.

Still, I think there are some very good reasons to pay attention to what the state’s model is telling us here.

Here’s why…

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