In the comment thread on an earlier post, Steven writes:
Somebody around these parts had a pretty good suggestion a while back. If you want to see what the surface option looks like, let’s close the Viaduct for a month and see how traffic responds. Then let’s vote.
The implication being that with the Viaduct closed, I-5 will slow to a permanent crawl while the city’s side streets are choked with drivers seeking alternative routes.
Of course, that’s a completely bullshit analysis, no matter how many times people repeat it. First of all, the surface-plus-transit option is not the do-nothing option — it is the s u r f a c e – p l u s – t r a n s i t option, which means it includes a number of surface and transit improvements to move additional vehicles and people through our existing surface streets. Improvements which would presumably include, um, a new, multilane boulevard in the shadow of the existing Viaduct.
Replacing the Viaduct with $2.4 billion worth of transit and street improvements is not the same thing as simply closing it. Would the surface-plus-transit option, whatever it entails, match the vehicle capacity of the existing elevated structure? Probably not. But it would provide a helluva lot more capacity than doing nothing.
The second problem with Steven’s thought experiment is that one month isn’t nearly enough time for local commuters to change their driving habits, especially knowing that things will return to normal after 30-days. But faced with years of Viaduct closure and disruption, well, that’s when all that seemingly superfluous grey matter tucked behind our foreheads really starts to kick into gear. It may not seem like it while they’re blindly cutting you off in traffic, but the average driver is smarter than your average bear, and will eventually adjust their driving habits to fit the new reality. Just as new freeway capacity attracts more traffic, reducing capacity will discourage some trips and reroute others.
So, how long would it really take to conduct Steven’s thought experiment under objective, real-world conditions? Well, according to WSDOT, if we end up rebuilding a new elevated structure, SR 99 will be shut down in whole or in part for up to 10 to 12 years.
That’s right, drivers will be forced to live without the existing capacity for over a decade.
During this decade of disruption, a Downtown Seattle Association comparison matrix shows that SR 99 would close nights and weekends for 5 to 7 years, and be reduced to two-lanes in each direction for 7 years. Various southbound segments will be closed for periods of time ranging from 6 to 21 months, while the entire structure would be closed in both directions for as long as 9 months.
And that’s if everything goes according to plan.
So when surface critics talk about how Seattle’s economy is going to completely collapse if we lose the Viaduct’s current vehicle capacity, I wonder how they think we’re going to survive the decade or so it will take to rebuild it?