Item No. 7b_supp
Meeting Date: May 12, 2020
West Seattle Bridge Update
Staff Briefing
May 12, 2012

Overview
Introduction
City of Seattle Presentation by Seattle Department of
Transportation (SDOT)
External Engagement
Internal Working Groups
Next Steps
Questions
2

Introduction
Background
Why it matters
SDOT's "West
Seattle High-Rise
Bridge Safety
Project"

3

West Seattle High-Rise Bridge Safety Project



Port of Seattle Commission
Sam Zimbabwe and Heather Marx
May 12, 2020Department of Transportation

Presentation overview
Background and what has changed since March 23
Future of the bridge
Traffic Mitigation
Communication and outreach

Department of Transportation                              2



Bridge Background and Details
Opened for use in 1984
Cast-in-place concrete and steel
bridge
One-of-a-kind, uniquely designed
for our topography and geography
Designed for three lanes in either
direction
Highest daily traffic volumes among
SDOT roadways
84,000 vehicles (2019)
17,000 transit riders                        This Photo by Unknown Author is licensed under CC BY-SA
Department of Transportation                              3

What has changed since March 23, 2020
Background
Bridge closed on March 23 due to rapid growth in
cracking along the center section of the bridge
The bridge was built to the standards, and using
the best computation methods, of the day
Recent findings
Recent inspections have found cracks continue to
grow, but at slower rate, confirming immediate
removal of live load was essential
SDOT has a better understanding of stabilization
timeline, but there is still uncertainty

Department of Transportation                              4

Safety is top priority
SDOT continues to inspect the bridge daily
Bridge is safe for crews
We are installing intelligent monitoring
equipment to alert us to any changes in
the bridge in real time
We are modeling potential cracking
scenarios and preparing contingency plans
These plans will enable rapid response to
preserve public safety
We are working with the Port, NWSA, SPD,
SFD, the Coast Guard, Army Corps and
others on a safety management plan

Department of Transportation                              5

Be prepared, sign up for AlertSeattle today


AlertSeattle is the official emergency notification system used by the City of
Seattle to communicate with city residents during emergencies
Sign up at alert.seattle.gov to receive free alerts from the City via text message,
email, voice message or social media
Department of Transportation                              6

Future of the Bridge Remains Uncertain
SDOT does not yet know if repair of the
bridge is feasible technically or
financially
If repair is feasible, it could provide up to
10 years of additional use
We do not anticipate traffic returning to
the bridge in 2020 or 2021
We are committed to clear
communication and transparency
throughout

Department of Transportation                              7

Stabilization and shoring schedule
OngoingContinue field inspection and install instrumentation hardware/real
time alerts
ImmediatelyPier 18 restraint release design
SpringShoring and repair design begin, technical advisory panel for peer review
launched
SummerPier 18 restraint released; shoring materials procurement begins
Late FallShoring construction begins
Early Spring 2021Shoring construction complete

Department of Transportation                              8

Phase I: Slow deterioration & plan next steps
On March 23, SDOT discovered the rapid growth of previously observed cracking.
Cracking has slowed since we removed traffic.
A new intelligent monitoring system will help us identify why the bridge is cracking
and serve as an early-warning system if the bridge seems likely to fail.
SDOT procured Kraemer North America to perform immediate
emergency repairs, including:
Temporary crack arrest measures, such as carbon fiber wrapping, to stabilize
the bridge and slow deterioration.
Repair of Pier 18's lateral bearings; they are compressed so that the bridge
cannot move as it is designed to do. This is affecting the whole bridge and
contributing to abnormal cracking.

Department of Transportation                              9

Stabilization through Pier 18 repairs
To slow cracking, unlocking Pier 18 lateral bearings is the top priority for repair
Repairing the locked bearings is contingent on bridge strength analysis to determine
if the bridge can handle the stress
SDOT procured Kraemer North America to perform these immediate emergency
repairs



Department of Transportation                              10

Phase II: Shoring the bridge to further stabilize
The process of "shoring" means adding temporary support to the bridge to
preserve its integrity and enable repairs.
Mid-2020  design shoring system; obtain and build specially fabricated materials
for shoring while Pier 18 repairs are made.
Late 2020  Shoring construction.



Department of Transportation                              11

Phase III: Bridge Repair
Key elements of uncertainty right now:
Can bridge be stabilized before further
deterioration makes repair infeasible?
Will repair require permits to impact the
navigation channel?
Will repair require special fabrication or
equipment?
Is repair feasible technically
or financially?
We are at 0 percent design, and each step
will impact what's doable and timeline
Department of Transportation                              12

Traffic Mitigations  Low Bridge
Closing the West Seattle Bridge
has a similar level of complexity to
our recent Viaduct closure, but
with fewer re-route choices, and
shorter timeline
Low Bridge restricted to people
driving emergency vehicles, freight
trucks, and public transit
Seattle Police Department is
supporting enforcement
Path open to people walking and
biking
Access to Harbor Island for general
public via east channel bridge

Department of Transportation                              13

Traffic Mitigations 
Detour Routes
Traffic signal installed at Highland Park
Way SW and SW Holden St
Improved detour route signage
Repaved the 5-way intersection west of
the Spokane Street/Low Bridge
Added six real-time cameras to traffic
locations
Adjusted signal timing at 13
intersections
Installed three dynamic message signs
to display travel times via West Marginal
Way

Department of Transportation                              14

Significant change in travel lanes
With the High Bridge closure, we've lost 9
traffic lanes of capacity.
Transit service capacity is limited by
social-distancing requirements
We need more options to move West
Seattle commuters on and off the
peninsula
Plus strategies to maintain freight and
urban goods and manage cut-through
traffic
SDOT, Metro and the Port are identifying
projects
Private business and mobility providers
are needed as partners to bring options
to the table

Department of Transportation                              15

How will we move people?
Current traffic management
improvements:
Operational improvements on detour
routes  signals, traffic monitoring,
potholes, rechannelization
DRAFT Traffic mitigation plans  by
June 30 for public input
Neighborhoods affected by cut-through
traffic
Freight
Bicycles
West Seattle travelers
Department of Transportation                              16

Traffic Mitigation  Potential Strategies
Transit service and route changes          Carpools and Vanpools
Telework and flexible work schedules   Employer Shuttles
post COVID                            West Seattle work sites
Strategies to improve bicycle use          Curbside and parking management
Waterbourne transit frequency and       Construction management
access
And what else?
First and last mile connections 
shuttles, park-and-rides, micro-
mobility

Department of Transportation                              17

Communication and Outreach
Work closely with the Port of Seattle and the Northwest Seaport Alliance to
engage maritime and industrial stakeholders, inform emergency contingency
plans and identify traffic mitigation strategies
Work with West Seattle, South Park, Georgetown and SODO communities and
businesses to keep people informed, provide resources, and answer questions
Host monthly Maritime Industry Town Halls with Port and NSWA
Share email updates with subscribers so they hear from SDOT about what's
happening and how to get around
Publish regular blog updates to keep people informed

Department of Transportation                              18

External Engagement
The interagency structure used under the Alaskan Way Viaduct
Replacement Program is being reconfigured to support the WSB
response/replacement:
Executive Oversight; Interagency Leadership; Communications
Group; Traffic and Operations; Performance Monitoring
In addition, other efforts already underway:
Twice Weekly Interagency Check-in
Emergency Continency Planning
Maritime and Industrial Stakeholder Facilitation
West Seattle, South Park, Georgetown and SODO Engagement

22

Internal Working Groups
Executive Committee: ensure Port and NWSA senior management is well informed
and can provide regular input as the response and replacement process unfolds.
Emergency Contingency Planning: support the City led interagency task force in
establishing a safety management plan in the unlikely event of a catastrophic failure
of the high bridge.
Operational Strategy and Performance Monitoring: serve as a clearing house,
collecting and developing the data and analysis that will be needed to work
productively with the City to ensure adequate landside access and egress for Port
and NWSA facilities beyond emergency/contingency planning.
Water Transportation: draft proposal as to how the Port and NWSA can support the
broadened movement of people and goods via water routes.
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Internal Working Groups continued
Transit: coordinate strategy with external partners on expanded transit needs in
light of the closure (e.g. working with Metro for additional stop near Harbor Island)
and provide guidance around Port/NWSA employee mobility needs.
Replacement Strategy: prepare and, upon approval, execute the strategy around
Port/NWSA support for the WSB repair/replacement.
Outreach and Communications: set the recommended strategy for external
outreach and communications activities.


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Next Steps
Recommended strategies and tactics to Commission and Executive
Continued outreach and communications to maritime and industrial stakeholders as
well as to impacted communities in partnership with the City (e.g. South Park, West
Seattle, Georgetown, SODO)
Continued interagency engagement at all levels of the response
Future briefings


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Questions?


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