IOWA ACCELERATED BRIDGE CONSTRUCTION Norm McDonald, PE 2014 ASCE Transportation Conference November 5, 2014 Ames
ABC Definition • ABC is bridge construction that uses innovative planning, design, materials and construction methods in a safe and cost- effective manner to reduce the on site construction time that occurs when building new bridges or replacing and rehabilitating existing bridges. - FHWA Accelerated Bridge Construction Final Manual
Mobility Impact Time • Tier 5 – Overall project schedule is significantly reduced by months to years. • Tier 4 – Traffic impacts within 3 months. • Tier 3 – Traffic impacts within 2 weeks. • Tier 2 – Traffic impacts within 3 days. • Tier 1 – Traffic impacts within 1 to 24 hours. - FHWA Accelerated Bridge Construction Final Manual
ABC Techniques • Prefabricated Bridge Elements and Systems (PBES) • Precast elements • Self-propelled modular transporters (SPMT) • Slide-In Bridge Construction (SIBC) • Innovative Contracting • A+B Bidding • I/D Contracts • Lane Rental
Why use ABC? • To deal with schedule constraints • Limited time-window due to special events • Emergency replacement due to natural disasters, accidents, or intentional acts • To minimize impact on local traffic • Access to business • Commuters • Essential services • To deal with the unavailability of suitable detour
ABC: Benefits • Reduced public inconvenience • Improved public perception • Improved road users and workers safety • Reduce negative economic impact on local businesses • Improve the durability of the structure
Iowa’s ABC Experience • 11 Demonstration projects constructed to date • Focus on a variety of PBES • Focus on I/D contracting • Grants – IBRC, IBRD, SHRP2 R04, HFL • 5 Projects currently in Final Design • 2 Projects currently in Preliminary Design
Presentation Overview • Five Key Projects • Mackey Bridge - 2006 • Madison Bridge - 2006 • 24 th Street Bridge - 2008 • Keg Creek Bridge - 2011 • Massena Bridge - 2013 • ABC Policy
Mackey Bridge
Mackey Bridge Name Mackey Bridge Location 120th Street over Squaw Creek Year Constructed 2006 Owner Boone County Engineer Iowa DOT Bridge Type PPCB Size 151' ‐ 4 x 30' ‐ 6 Spans 47' ‐ 5, 56' ‐ 6, 47' ‐ 5 ABC Technologies Precast Abutment Footing Precast Pier Caps Full ‐ Depth Precast Deck Panels Total Project Bid $737,098.11 Bridge Unit Cost* $90/SF ABC Contract Period None Grant IBRC *Traditional unit cost at this time for PPCB = $60/SF
Mackey Bridge
Mackey Bridge
Mackey Bridge
Mackey Bridge • Lessons Learned • The precast concrete footing/cap to pile connection is a highlight of the project. • Consider prestressing precast elements. • PPC Beam flange width. • Haunch forming system. • Deck panel post-tensioning: • Panel casting tolerance. • Stress distribution from pt.
Madison Bridge
Madison Bridge Name Madison Bridge Location 290th Street over Branch Clanton Creek Year Constructed 2006 Owner Madison County Engineer Iowa DOT Bridge Type Precast Box Beam Size 46' ‐ 8 x 24' Span 46' ‐ 8 ABC Technologies Precast Abutment Footing Precast Box Beams Total Project Bid $159,937 Bridge Unit Cost* $98/SF ABC Contract Period None Grant IBRC *No traditional unit cost data available for box beam bridges
Madison Bridge
Madison Bridge
Madison Bridge • Lessons Learned • The contractor’s temporary support method for the precast footing with flowable mortar fill worked well. • The cast-in-place concrete closure diaphragm added time to the critical path and was subsequently changed to a precast piece in a future similar project.
Buena Vista County 28'-0" Grouted Keys Steel Post 4'-0" x 1'9" and Guardrail Deck Beam 1'-9" 2 - 7 8 " Dia. x 5" Studs Ea. Side Neoprene of Pile (Typ.) Bearing Pad 3'-3" 3'-0" 2'-0" HP 10 x 57 1'-9" Ø Galvanized Grout Void 3'-0" Wide Precast Steel Bearing Pile C.M.P. Pile Sleeve Solid Cap Beam 4 Pile Spaces @ 6'-0" = 24'-0" 2'-1" 2'-1" 28'-2"
Buena Vista County
24 th Street Bridge
24 th Street Bridge Name 24th Street Bridge in Council Bluffs Location 24th Street over I ‐ 29/I ‐ 80 Year Constructed 2008 Owner Iowa DOT Engineer HDR, Inc. Bridge Type CWG Size 353' ‐ 6 x 82' Spans 178' ‐ 6, 175' ‐ 0 ABC Technology Full ‐ Depth Precast Deck Panels Total Project Bid $12,506,262.87 Bridge Unit Cost* $140/SF ABC Contract Period A+B with 210 days max. @ $1,500/day Grant HfL *Traditional unit cost at this time for CWG = $120/SF
24 th Street Bridge
24 th Street Bridge
24 th Street Bridge • Lessons Learned • Sand blasting is the preferred method for roughening the concrete surfaces for bonding precast concrete to cast-in-place concrete • Transverse joint detail • Incentive/Disincentive amount needs to be commensurate with the project size
Keg Creek Bridge
Keg Creek Bridge Name Keg Creek Location US 6 over Keg Creek Year Constructed 2011 Owner Iowa DOT Engineer HNTB Corporation Bridge Type Rolled Steel I Girder Size 204' ‐ 6 x 44' ‐ 0 Spans 67' ‐ 3, 70' ‐ 0, 67' ‐ 3 ABC Technologies Precast Abutment Footing Precast Wingwalls Precast Pier Caps Precast Pier Columns Modular Units UHPC Joints Grouted Splice Couplers Total Project Bid $2,658,823.35 Bridge Unit Cost* $161/SF ABC Contract Period 14 day critical closure w/ $22,000/day I/D Grant SHRP2 R04 *Traditional unit cost at this time for I Girder = $90/SF
14-Day ABC Timeline Actual ABC period: October 17 – November 1
Iowa Bridge Farm
Superstructure Modules – Structural Steel Assembly
Modules – Deck Superstructure Forming
Placement Concrete Deck
Keg Creek Bridge
Keg Creek Bridge
Cap Beam Assembly 168 kips
Keg Creek Bridge
Keg Creek Bridge
Keg Creek Bridge • Lessons Learned • Grouted splice couplers are promising – template is critical. • Modular unit deck reinforcing congestion. • Semi-integral abutment overhanging backwall detail needs improvement. • Survey, survey, survey! Not just an ABC issue. • Inspector training and project demands.
Massena Bridge
Massena Bridge
BRIDGE CONSTRUCTION VISUALIZATION
Mobility Impacts & ABC Consideration • Original concept: Six months road closure • 7 miles out of distance travel for detour • AADT (2012) – 1,460 w/ 16% trucks • User costs for 180 day detour • Indirect $437,000 • Direct $15,000 (road maintenance & detour signing) • User costs for a 9 day road closure • $22,000
Massena Bridge Name Massena Lateral Slide Location IA 92 over Small Stream Year Constructed 2013 Owner Iowa DOT Engineer Iowa DOT Bridge Type PPCB Size 120' ‐ 0 x 44' ‐ 0 Span 120' Key ABC Technologies Slide ‐ In Bridge Construction (SIBC) Precast Wingwalls Precast Abutment Footing Total Project Bid $1,346,647.90 Bridge Unit Cost* $112/SF ABC Contract Period 9 day critical closure w/ $10,000/day I/D Grant HfL *Traditional unit cost at this time for PPCB = $85/SF
Massena Bridge
Massena Bridge
Massena Bridge
Massena Bridge
Massena Bridge • Lessons Learned • Let ABC projects in the fall. • I/D time increment – days v. hours. • For the abutment footing let with a C.I.P. and precast concrete alternate. • Pile size considerations HP14x117. • Pile driving acceptance criteria. • Falsework inspection.
ABC Policy • Developed in 2012 • First level screening • Average Annual Daily Traffic • Out of distance travel • Daily road user cost • Economy of scale
ABC RATING SCORE FACTORS AND WEIGHTS Measures Score Weight Weighted Maximum Weighted Factor Score Score Maximum Score Average Annual Daily Traffic 5 10 50 5 50 Out of Distance Travel 2 10 20 5 50 Daily Road User Costs 4 40 5 50 10 Economy of Scale 2 10 3 15 5 Total Score 120 Max Score 165 ABC Rating Score (Total Score/Max Score)x100= 73
ABC Policy
55 AHP Analysis Details • AHP (Analytic Hierarchy Process) is a decision- making technique designed to select the best alternative from a set of alternatives evaluated against several criteria. • The decision maker performs pair-wise comparisons that are used to develop an overall priority ranking for each alternative.
AHP Analysis Details Comparisons are also used to assess the extent to which one alternative satisfies a criteria over another alternative. Alt B Alt B Alt A Alt A 4 3 1 4 7 8 2 2 3 5 6 9 9 8 7 6 5 Direct Costs Alt B Alt B Alt A Alt A 4 3 1 4 7 8 2 2 3 5 6 9 9 8 7 6 5 Indirect Costs
ABC Policy • Final concept recommending ABC approach with desired ABC schedule & method. • Tier 1: Traffic Impacts within 1 to 24 hours • Tier 2: Traffic Impacts within 3 days • Tier 3: Traffic Impacts within 2 weeks • Tier 4: Traffic Impacts within 3 months • Tier 5: Traffic Impacts from 3 months to years
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