I-5, Skagit River Bridge Collapse First Annual Missouri Bridge Conference

April 9, 2015 Columbia, MO

Jugesh Kapur, PE, SE

I-5, Skagit River Bridge Collapse• Bridge collapses on May 23,

2013• Struck by over height truck• I-5 the only N-S interstate in WA

state w/ ADT = 71,000• $14 billion of US-Canada

commerce passes thru I-5 annually

Courtesy: WSDOT

Collapsed Bridge

Courtesy: WSDOT

I-5, Skagit River Bridge Collapse

Courtesy: WSDOT

First Steps

1. Within 24 hrs – Assembled team to evaluate replacement options

2. Within 24 hrs – Selected contractor (force acct.) to remove debris

3. Within 48 hrs – Options for temp. bridge alternatives evaluated – 30 day emergency contract executed

4. Within 72 hrs – Governor and Secretary of Transportation announce plans to install temp. span w/in 30 days and reopen I-5

Courtesy: WSDOT

Next Steps

• Coordination w/ NTSB investigation

• Inspection of remaining trusses & piers

• Repairs to remaining trusses• ACROW temp bridge ordered

and pier supports modified

Courtesy: WSDOT

Temp. Span Details• Acrow panels – arrived w/in 5

days• Two temp. bridges placed side by

side using launching technique• Speed reduced to 40 mph• Opened to traffic in 27 days

Courtesy: WSDOT

Perm. Span Contract Details

1. Accelerated RFP Process

2. A+B+C = Best Value Approach

A= # hours of total closure x $660K/day B= Days past Sept 4th x $50K C= Price proposal

3. Two week proposal period – from RFP to award

4. Best value award $6.9M – Max J. Kuney & PB team

5. Anticipated opening of Sept 5th w/ 12 hr. total closure Courtesy: WSDOT

Perm. Span Options

1. Precast, prestressed deck bulb tee girders (59” deep)

2. Lightweight concrete deck bulb tee girders (65” deep)

3. Steel girders (6’ deep) w/ 3.5” precast stay-in-place panels w/ 5” CIP concrete topping

4. Steel plate girders (5’-6” deep) with CIP slab

5. WSDOT obtained all environ. permits, ROW , detour permits, etc.

Courtesy: WSDOT

Preferred Alternate

Modified deck bulb tees (lightweight concrete) chosen for:

1. Shorter fabrication time2. Greater schedule control3. Conventional construction4. Concrete wt. = 133pcf

Challenges :

1. Concrete superstructure weight less than 915 tons

2. Weight for shipping and erection

Courtesy: WSDOT

Girder Connection Details

1. Headed bars used between girders (first use in WA, based on NCHRP 12-69 research); staggered between girders

2. Full moment connection

Courtesy: WSDOT

Camber Challenges

1. Predicted camber – 5.5”

2. Vertical profile - 1.5”

3. Pre-cambered the girder forms - 4.375”

4. Used 1.5” modified concrete overlay

Courtesy: WSDOT

Perm. Span Details

Replacement Scheme – Lateral Slide

Courtesy: WSDOT

Lateral Slide Details1. Push & reset system2. 2 – 150 M-ton jacks one on each side for lateral move; 4 –

150 M-tons for vert. movement 3. Total lateral move – 75 ft4. Skid beam w/ clad stainless steel sheets; support beams w/

Teflon surface

Courtesy: WSDOT

Temp. Bents – Special Feature

Special truss span = 77 ft.

Courtesy: WSDOT

Skid Track Details

Courtesy: WSDOT

1 7

Modified Concrete Overlay

• 1 ½” modified concrete overlay• 42 hours cure time• Deck temperature between 450-750F

Courtesy: WSDOT

Placement Details

Courtesy: WSDOT

Lowering Span To Final Position

Courtesy: WSDOT

Bridge Move Summary

1. 19 hours full road closure2. Temp. span out in 25 minutes3. Permanent span into place in 45 minutes4. Superstructure lowering in 30 minutes

Courtesy: WSDOT

2 1

NTSB’s Findings (failure mechanism)

1. Truck hits the sway brace2. Vertical member L4-U4 is deformed3. Upper chord U3-U5 pulled downward4. Bucking failure in upper chord at node U4

NTSB’s Findings

1. Load 2” taller than permitted.2. Pilot car distracted by cellphone (although hands-free);

claimed that clearance pole never struck the bridge.3. Insufficient distance between pilot car and truck (less than

1/2 of what it should be).4. States should have better warnings for low-clearance

bridges.5. Provide lane specific guidance for bridge clearance.

Vertical Clearance Upgrade

Courtesy: WSDOT

Thank you.