The case for the deep bore tunnel
Right now, a drill rig is outside on First Avenue, testing soil conditions for the deep bore tunnel. The plan is far from certain obviously, but progress of any kind is exciting! Meanwhile it’s working its way through the legislature. This is a good time to hit some key points and dispel some misconceptions.
The tunnel would have more capacity than the current tunnel, not less. The same two lanes each way, plus breakdown lanes that avoid backups. The missing third lane is replaced by people exiting before Downtown rather than in Downtown.
It might save money vs. the alternatives despite costing more. What’s the price of several years of massive disruption with the aerial or shallow-cut alternatives? How many stores would fail, offices would move away, residents wouldn’t move in, and tourists wouldn’t come? (not to mention the effect of being next to another eyesore for another lifetime)
It’s realistic about traffic. The surface-option supporters have great motives. But they’re mistaken. Better transit would reduce trips somewhat, and many drivers might simply move. But tens of thousands of cars per day would be added to surface streets. Political concessions to the driving public would turn Downtown streets into highways focused on throughput rather than those who work, live, or shop here. For example, the PI instantly suggested fewer pedestrian crossings when the original surface option was shortlisted. 
A tunnel helps Downtown function. Downtown Seattle is the dominant economic engine of our region, and plays an important role for most locals, whether working here, attending events, or just getting through. It’s tough to concentrate so much activity in a narrow area, but we do pretty well because of tunnels, including the BN tunnel, the transit tunnel, the existing 99 tunnel, and even the covered part of I-5. Downtown is growing. Putting 99 underground gets the through traffic through (without encouraging more driving) while allowing Downtown to be what it can be.
It avoids another 50-year mistake. Cities that succeed in the coming decades will have quality of life (as well as functionality; see above). The central waterfront and our surface streets are essential parts of that.
I think it’ll pass. The plan mixes best-case attributes and lacks strong anti constituencies. The ”view while driving” crowd seems numerous but they ought to watch the road and will look foolish if the initiative goes anywhere. Through-drivers get their freeway (without more lanes to encourage more driving), Interbay gets a wider Alaskan Way and non-jammed streets, transit users end up with more transit (even if indirectly), Downtown people get our great waterfront and hold on to our walkability, and locals shoulder the difference in cost, which is a manageable figure.
PS, did everyone notice that Sound Transit just bid two two tunnel sections for massively less than projected? They came in 23 percent and 34 percent under Sound Transit’s estimates, at a combined $329 million rather than $425 million. This is encouraging for the deep bore 99!
Tags: Downtown Seattle, Highway 99, tunnel, Viaduct, walkability
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