I-5 Bridge over the Skagit River collapses in Washington State

This is breaking news, and this blog post will be out of date.

The Interstate 5 bridge over the Skagit River has collapsed near Mount Vernon, Washington. A map shows where the incident happened, about half way between Seattle and the Canadian border.

I-5-Bridge-Collapse-Mount-Vernon-Washington-Skagit-River-Google-Map
As of this writing there are no confirmed details about the cause of the bridge collapse. The Seattle Times says it may have been because an oversized truck hit the bridge with its load. Three people were rescued from the water with minor injuries.

Some sources:

Scanner, via Broadcastify: Skagit County Police and Fire.  4400+ listeners at 8:19 p.m. 5/23/13. This is the initial police response, via Soundcloud and Alertpage.

 

Skagit Valley-News: Reports: Bridge collapses between Mount Vernon, Burlington

The I-5 Skagit River Bridge is a through-truss bridge that was built in 1955, according to the website Bridgehunter.com. It is the same basic type of design of the Interstate 5 Bridge over the Columbia River in Vancouver, according to the site.

Associated Press: I-5 bridge collapses in NW Wash.; people in water.

Bridgehunter.com: I-5 Skagit River Bridge. Includes maps and photos of bridge.

National Bridge Inventory Database details follow, from NationalBridges.com. The structural evaluation is "Somewhat better than minimum adequacy to tolerate being left in place as is".

State: WA
Place Name: Mount Vernon
County: Skagit
NBI Structure Number: 0004794A0000000
Route Sign Prefix: Interstate
Route Number: 5
Facility Carried: I-5
Feature Intersected: SKAGIT RIVER
Location: 0.7 N JCT SR 538
Year Built: 1955
Status: Functionally Obsolete
RecordType: Roadway is carried ON the structure
Level of Service: Mainline roadway
Owner: State Highway Agency
Highway Agency District: 01
Maintenance Responsibility: State Highway Agency
Functional Class: Principal Arterial – Interstate, Urban
Service On Bridge: Highway
Service Under Bridge: Highway-waterway
Latitude: 48 26 35.80 N
Longitude: 122 20 27.90 W
Material Design: Steel
Design Construction: Truss – Thru
Approach Material Design: Concrete continuous
Approach Design Construction: Tee Beam
Structure Length (m): 338.9
Navigation Vertical Clearance (m): 2.4
Approach Roadway Width (m): 21.9
Lanes on Structure: 4
Lanes under Structure: 4
Average Daily Traffic: 70925
Year of Average Daily Traffic: 2010
Design Load: MS 18
Scour: Bridge foundations determined to be stable for assessed or calculated scour condition.
Bridge Railings: Meet currently acceptable standards.
Historical Significance: Bridge is not eligible for the National Register of Historic Places.
# of Spans in Main Structure: 4
# of Spans in Approach Structures: 8
StructureFlared: No flare
Transitions: Does not meet currently acceptable standards.
Approach Guardrail: Meets currently acceptable standards.
Approach Guardrail Ends: Not Applicable
Navigation Control: Navigation control on waterawy (bridge permit required).
Navigation Horizontal Clearance (m): 33.5
Structure Open?: Open, no restrictions
Deck: Satisfactory Condition
Superstructure: Fair Condition
Substructure: Satisfactory Condition
Structural Evaluation: Somewhat better than minimum adequacy to tolerate being left in place as is
Sufficiency Rating (%): 57.4

 News coverage – this may change as time progresses:

KING 5 live coverage.

I-5-Bridge-Collapse-Skagit-River-KING-5-Screencap
KIRO 7 live coverage.

I-5-Bridge-Collapse-Skagit-River-KIRO-7-Screencap

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