The land rolls like waves as it liquefies beneath the viaduct. As spliced timber piles underpinning the columns lose lateral support, the piles buckle and some viaduct columns drop swiftly out of sight. Utilities rupture, fires break out and roadway decks collapse with shocking speed.
Is it a scene from a new disaster movie? No. It’s a simulation of an engineering model-driven video showing what would happen to the Seattle’s Alaskan Way Viaduct in the case of a serious earthquake.
A political storm set off by the Washington State Dept. of Transportation’s release of the video is expected to die down now that the Nov. 3 mayoral election has passed. By most accounts, the video didn’t sway the election. Mike McGinn, who ran on a no-tunnel platform, won by a sliver and he promises not to stop the tunnel planned to replace the viaduct.
Created by Parsons Brinckerhoff’s Seattle office in 2007, the video shows the collapse of the aging viaduct and dramatic damage to the surrounding area. The physics are based on the Nisqually earthquake of 2001, which rattled the same area, but with the epicenter moved closer, the intensity increased 6.9 to 7.0 and the duration extended to 60 seconds. The simulation follows the profile of a quake seismologists calculate has a one-in-ten chance of striking the area in the next ten years.
It was that probability calculation, which was released based on new data in 2007, that caused WSDOT to ask PB to model the effects of such a quake on the old Alaskan Way Viaduct. City leaders are intent on replacing the viaduct due to age and deterioration and its susceptibility of catastrophic failure in a serious quake. PB had created structural, utility and geologic models to help study viaduct replacements. But seismic forces introduced an unsettling graphic demonstration and the video was so distressing WSDOT decided not to release it, although the technical report that lay behind it was released in Nov. 2007.
Then the $2.4-billion viaduct replacement project and its funding became a point of contention in the recent election between the Seattle mayoral candidates. Current plans for the viaduct call for it to be torn down and replaced with a bored tunnel starting in 2010, although some candidates were vowing to block the process, if elected.
Into the middle of this controversy, two weeks before the election, WSDOT dropped the quake video. One of the primary candidates had demanded its disclosure.
“The timing was purely coincidental,” says Ron Paananen, the DOT’s project manager for the viaduct replacement.
Charges flew that WSDOT was trying to influence the election, or that one of Parsons Brinckerhoff’s team had played a hand in an attempt to swing the vote to candidate Joe Mallahn, who was likely to back the tunnel plan and allegedly would have positioned the firm for a role in performing the work. But as a consultant helping WSDOT scope the project and prepare the request for proposals, PB is precluded from participation.
Now the issue is presumably moot because McGinn eventually beat fellow Democrat Mallahan, winning 51% of the votes that were finally tallied Nov. 9.