Reconstruction of the Eads Bridge Highway Deck Michael J. Cronin, PE, SE

Eads Bridge History Opened to traffic July 4, 1874 Designed and planned by James Buchanan Eads Underwater salvage expert Shipbuilder No formal education Hired by the St. Louis and Illinois Bridge Company as engineer-in-chief for this project

Eads Bridge History Design and construction innovations deep pressurized caisson construction

Eads Bridge History Design and construction innovations deep pressurized caisson construction high strength cast steel

Eads Bridge History Design and construction innovations deep pressurized caisson construction high strength cast steel design of components to permit ease of replacement

Eads Bridge History Design and construction innovations deep pressurized caisson construction high strength cast steel design of components to permit ease of replacement cantilever construction of main arch spans

Eads Bridge History Design and construction innovations Deep pressurized caisson construction high strength cast steel design of components to permit ease of replacement cantilever construction of main arch spans 500 ft spans were 200 ft longer than any built previously

Bridge Ownership History Illinois and St Louis Bridge Company Missouri Pacific Railroad Company Terminal Railroad Association City of St. Louis / Bi-State Development Agency

Rehabilitation Challenges Preserve historically important aesthetic elements Use existing substructure to support new highway deck Maintain light rail traffic during construction

New Cross Section Four 11 ft lanes designed for HS-20 loading 1 ft offset between outside lanes and the Jersey barriers 5 ft sidewalk on south side of roadway

Bridge Sections West Approach West Arcade Main Spans East Arcade East Approach

West Approach & East Arcade Substructure: 3 longitudinal walls Outside walls of stone or brick masonry, original construction Center wall of minimally reinforce concrete, constructed in the 1920’s Substructure repairs Tuckpointing Crack repair Reinforced concrete pads

West Approach & East Arcade Longitudinal concrete beams over First and Second Streets Spalled and cracked Some section loss in reinforcing Capacity found to be marginally acceptable Repairs fiber composite wrap total replacement

West Approach & East Arcade Existing superstructure: transverse concrete floorbeams with distinctive sloped ends Replaced with prestressed concrete I girders with special ends designed as 2 span continuous to maintain distribution to supporting walls Precast SIP form panels utilized

West Arcade Substructure: 2 longitudinal walls East portion - stone masonry arches in fairly good condition concrete infill used to strengthen arches West portion - reinforced concrete open arches in poor condition total replacement with new reinforced concrete arches

West Arcade Existing superstructure non-composite rolled beams at 4 ft spacing deck replaced in early 1980’s design called for cleaning & painting beams, scarifying & overlaying deck Change order proposed by contractor total replacement of superstructure with composite rolled beams at 8.5 ft spacing

Main Spans Existing substructure - 2 piers and 2 abutments founded on bedrock Good condition Top surfaces of piers and abutments required crack repair and resurfacing

Main Spans Arch truss superstructure no retrofit required if dead load from new floor system and deck is held < 116 psf

Main Span Floor System Existing floor system: half-filled grid deck on floorbeams at 6 ft spacing New floor system eliminated floorbeams between columns - 12 ft spacing Exodermic™ Deck specified to span the 12 ft between floorbeams 74 psf using standard weight aggregate

Main Span Floor System The Exodermic™ deck, or an “unfilled steel grid deck composite with a ±4.5” reinforced concrete slab” provides: Light weight Structural efficiency Protection of Light Rail operating below

ExodermicTM Bridge Deck

Special Main Span Features Overlook areas at piers and abutments Bridge can be closed to traffic for special weekend events Electrical outlets built into north barrier

East Approach 10 spans of new steel superstructure on new concrete substructure - 1000 ft Highway deck starts above MetroLink track and end below Highway deck had to be built around MetroLink bridge and elevated station as well as abandoned foundations

East Approach Drilled shaft construction one shaft per pier up to 7 ft in diameter utilized to minimize footprint and to avoid vibrating adjacent MetroLink foundation

East Approach Steel straddle bents transverse beams support the highway deck over the MetroLink tracks and elevated station platform where traditional supports cannot be used

Connection to MetroLink Handicap accessible ramp built to connect sidewalk to East Riverfront Station

Reopening - July 4, 2003

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