IOWA ACCELERATED BRIDGE CONSTRUCTION

Norm McDonald, PE2014 ASCE Transportation ConferenceNovember 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• 24th Street Bridge - 2008• Keg Creek Bridge - 2011• Massena Bridge - 2013

• ABC Policy

Mackey Bridge

Mackey BridgeName Mackey BridgeLocation 120th Street over Squaw CreekYear Constructed 2006Owner Boone CountyEngineer Iowa DOTBridge Type PPCBSize 151'‐4 x 30'‐6Spans 47'‐5, 56'‐6, 47'‐5ABC Technologies Precast Abutment Footing

Precast Pier CapsFull‐Depth Precast Deck Panels

Total Project Bid $737,098.11Bridge Unit Cost* $90/SFABC Contract Period NoneGrant 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 BridgeName Madison BridgeLocation 290th Street over Branch Clanton CreekYear Constructed 2006Owner Madison CountyEngineer Iowa DOTBridge Type Precast Box BeamSize 46'‐8 x 24'Span 46'‐8ABC Technologies Precast Abutment Footing

Precast Box BeamsTotal Project Bid $159,937Bridge Unit Cost* $98/SFABC Contract Period NoneGrant 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

1'-9"

2'-1"

3'-0" 3'-3"

4 Pile Spaces @ 6'-0" = 24'-0" 2'-1"

2 - 78" Dia. x 5"Studs Ea. Sideof Pile (Typ.)

HP 10 x 57Steel Bearing Pile

1'-9" Ø GalvanizedC.M.P. Pile Sleeve

28'-0"

Steel Post and Guardrail

4'-0" x 1'9"Deck Beam

Grouted Keys

2'-0"

28'-2"

NeopreneBearing Pad

Grout VoidSolid

3'-0" Wide PrecastCap Beam

Buena Vista County

24th Street Bridge

24th Street BridgeName 24th Street Bridge in Council BluffsLocation 24th Street over I‐29/I‐80Year Constructed 2008Owner Iowa DOTEngineer HDR, Inc.Bridge Type CWGSize 353'‐6 x 82'Spans 178'‐6, 175'‐0ABC Technology Full‐Depth Precast Deck PanelsTotal Project Bid $12,506,262.87Bridge Unit Cost* $140/SFABC Contract Period A+B with 210 days max. @ $1,500/dayGrant HfL

*Traditional unit cost at this time for CWG = $120/SF

24th Street Bridge

24th Street Bridge

24th 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 BridgeName Keg CreekLocation US 6 over Keg CreekYear Constructed 2011Owner Iowa DOTEngineer HNTB CorporationBridge Type Rolled Steel I GirderSize 204'‐6 x 44'‐0Spans 67'‐3, 70'‐0, 67'‐3ABC Technologies Precast Abutment Footing

Precast WingwallsPrecast Pier CapsPrecast Pier ColumnsModular UnitsUHPC JointsGrouted Splice Couplers

Total Project Bid $2,658,823.35Bridge Unit Cost* $161/SFABC Contract Period 14 day critical closure w/ $22,000/day I/DGrant 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

SuperstructureModules –Structural Steel Assembly

Superstructure Modules – Deck Forming

Deck Concrete Placement

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 BridgeName Massena Lateral SlideLocation IA 92 over Small StreamYear Constructed 2013Owner Iowa DOTEngineer Iowa DOTBridge Type PPCBSize 120'‐0 x 44'‐0Span 120'Key ABC Technologies Slide‐In Bridge Construction (SIBC)

Precast WingwallsPrecast Abutment Footing

Total Project Bid $1,346,647.90Bridge Unit Cost* $112/SFABC Contract Period 9 day critical closure w/ $10,000/day I/DGrant 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

Measures Score Weight Factor

Weighted Score

Maximum Score

Weighted 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 10 40 5 50

Economy of Scale 2 5 10 3 15

Total Score 120 Max Score 165

ABC Rating Score (Total Score/Max Score)x100= 73

ABC RATING SCORE FACTORS AND WEIGHTS

ABC Policy

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.

55

AHP Analysis Details Comparisons are also used to assess the extent to which one alternative satisfies a criteria over another alternative.

Alt B9 8 7 6 5 4 3 2 987654321

9 8 7 6 5 4 3 2 987654321Alt A

Alt A

Alt B

Direct Costs

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

Additional Information

http://www.iowadot.gov/bridge/abc.htm

Google: Iowa DOT ABC

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