WEST SEATTLE BRIDGE CLOSURE: 3-scenario emergency plan finalized
(WSB photo from April)
By Tracy Record
West Seattle Blog editor
While the city’s been working toward stabilizing the West Seattle Bridge and determining whether it can be repaired, they’ve also been working on an emergency-response plan in case the bridge was deemed at imminent or near-imminent risk of collapse – which currently, they stress, it is NOT.
Most of this has been taking place out of the public eye, with the city working with “stakeholders” who have operations close to the bridge, such as the Port of Seattle. This came up during last week’s inaugural meeting of the community coalition West Seattle Bridge Now (WSB coverage here), when a port rep noted that this emergency plan was front and center right now. We’ve been pursuing more information from SDOT, and today they are announcing key points of the plan.
SDOT stresses that the bridge is “stable” and that the cracks’ growth has “slowed” since the bridge was closed to traffic March 23rd. But “out of an abundance of caution” they’ve devised this plan for how they would get the word out, and what people would need to do, if bridge failure seemed likely before stabilization work is complete.
What they’re releasing today is what SDOT communications director Michael Harold explained to us in an interview this morning is the “essence” of the emergency plan; the plan itself will be released “soon.” Today’s announcement first notes:
We’ve established an interagency task force to coordinate a unified emergency response if conditions of the high bridge reach critical thresholds.
The task force includes the City of Seattle, King County, Washington State, Port of Seattle, Northwest Seaport Alliance, United States Coast Guard (USCG), and the US Army Corps of Engineers.
If we must activate the task force’s unified emergency response, a unified command will be led by the Seattle Fire Department (SFD), the Seattle Department of Transportation (SDOT), the Seattle Police Department (SPD), and USCG.
These and other agencies will work together to prioritize public safety and provide clear communication. SDOT will manage traffic operations to assist emergency response and provide consistent updates to the public. SFD will manage evacuation and, if necessary, rescue of people near the bridge. SPD will manage traffic control and assist with evacuation. USCG will manage maritime coordination and communication. Seattle Public Utilities and Seattle City Light will manage utilities to reduce impact on customers.
SDOT stresses that the “only section of the West Seattle High-Rise Bridge that currently has cracks is the highest span directly over the Duwamish River between West Seattle and Harbor Island. … The rest of the bridge is relatively stable and doesn’t currently show signs of distress.”
But just in case, the emergency plan addresses three potential scenarios:
1) Immediate evacuation to be used if the daily in-person inspections indicates enough of a change to warrant the immediate evacuation of a small number of properties, though we could
have hours or days before actual bridge failure.
2) One to five days notice to be used if the new remote monitoring instrumentation, which will be fully functioning in mid May, indicates enough of a change to warrant execution of evacuation plans within one to five days. If failure is anticipated, but not immediate, SFD and SPD will clearly communicate, via direct site visits and other platforms, when evacuation must occur.
3) Controlled demolition to be used if the change in the condition of the high bridge indicates the need for execution of an evacuation plan followed by a controlled demolition.
The #1 response would involve evacuations in what’s considered “the Fall Zone.”
In what Harold calls a “very conservative estimate,” this area was identified via “modeling potential cracking scenarios” plus adding a buffer zone – it’s an area “225’ north and south of the bridge, 225’ west of Pier 15, and 225’ east of Pier 18, and includes the Spokane Street Low Bridge, parts of Harbor Island, the Duwamish Waterway, and areas on and around West Marginal Way.” (This is the type of information that the “critical failure modeling” mentioned in Councilmember Lisa Herbold‘s update last Friday is addressing – not an estimate of when a failure could happen, but of how it might happen, IF it happened.)
Even if they don’t have to evacuate, some on Harbor Island could see travel affected, so: “It is recommended that people on Harbor Island who are non-essential leave the island using the eastern approaches if they receive any notification that the West Seattle High-Rise Bridge is at risk. Those staying should know that emergency response could potentially block vehicle access to the island.” (added 2:07 pm – traffic map)
The Fall Zone does NOT include any residential areas, not even Pigeon Point adjacent to the bridge, SDOT says. But SFD and SPD would close access to nearby roads.
A mailer is being sent later this week to all addresses within a quarter-mile of the “fall zone,” Harold says. But in the meantime, even if you’re NOT that close, everyone in West Seattle is urged to sign up for Alert Seattle – an opt-in service through which emergency messages are sent and one way through which the city will send any bridge-related emergency notification.
Today’s announcement also says any bridge-related emergency alert will also be sent through “Wireless Emergency Alert (WEA) text messages … an alert system that sends text messages to all cell phones within a particular area. This is the same service that sends Amber Alerts. WEA will send text message alerts to all cell phones in the impacted area at the time of alert.” The Coast Guard also would send “an Urgent Marine Information Broadcast over VHF Channel 16 to warn mariners to avoid the Duwamish Waterway,
and they will use the USCG Alert Warning System to warn commercial operators and terminals on Harbor Island and the Duwamish Waterway.” Along with all those alerts, SDOT would also notify the media and publish warnings via its social-media channels.
But, Harold stresses yet again, they do NOT believe there is a risk of the bridge collapsing any time soon – they nonetheless have to be prepared. They’ve been installing instrumentation to enable real-time monitoring of the bridge status – in addition to continuing “near daily” inspections. We’ve asked how exactly that monitoring is being monitored, so to speak; Harold says they’ll be releasing those details this week too.
Questions? He says SDOT is ready to answer them via email or phone any time, 684-Road@seattle.gov or
206.684.ROAD (206-684-7623). Meantime, you also can find released-so-far info via the bridge-project website, where documents and information links are already archived.
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