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Broadway Street Viaduct Improvement, Pre-Load Testing and Geotech Report Workshop. Consultant Presentation Iowa DOT 2 nd April 2007. Workshop Goals. Agree on recommended bridge and foundation alternative to be carried forward into preliminary design.
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Broadway Street Viaduct Improvement, Pre-Load Testing and Geotech Report Workshop Consultant Presentation Iowa DOT 2nd April 2007
Workshop Goals • Agree on recommended bridge and foundation alternative to be carried forward into preliminary design. • Decide if bridge and geotechnical reports will be combined into one final report. • Discuss level of effort anticipated in conducting the pre-final design load testing program for the post-grouted drilled shafts
Overview of Bridge Replacement Options • Update to bridge options and schedules presented in the June 2006 Draft Bridge Report • Three bridge replacement options • Three bridge lengthening alternatives • Drilled shafts as foundations
Summary of Options Costs do not include approach slabs, demolition and mobilization.
Lengthening the Bridge • Construction Cost Implications • Soil Remediation and Retaining Wall Implications • Lengthening Options
Lengthening the Bridge • Alternate 1 • Extend bridge 37’-6” at east end • Extend bridge 25’-0” at west end • Sloping ground under bridge • MSE walls along sides • Alternate 2 • Extend bridge 100’-0” at east end • Provides 9’-0” min. vertical clearance under bridge • MSE walls in front of abutments • Alternate 3 • Extend bridge 200’-0” at west end • Extend bridge 250’-0” at east end • Provides 2’-0” min. vertical clearance under bridge • Soil remediation significantly reduced • Cantilevered retaining wall likely used for remaining short fill heights
Lengthening the Bridge Average Net Cost for Additional Bridge Length = $ 4,600 / ft.
Foundation and Soil Remediation Options • Post-grouted Drilled Shafts • Drilled Shafts Socketed in Bedrock • CMC Ground Improvements at Bridge Approaches • Lightweight Foamed Concrete Fill at Approaches
Drilled Shaft Load Test Program • Expected Schedule • Level of Effort Required from CH2M HILL
Bridge Aesthetics • Piers, Abutments, Retaining Walls • Bridge Railings, Barriers, Beams • Coloring textures, Rustications • Lighting