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.  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

Information from February 2006 PIM

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

Bridge Construction Costs

Summary of Options Option Estimated Construction Cost Estimated Time For Completion 1. Least Cost $ 10.1 million 10 months 2. Shortest Schedule $ 16.5 million 7 months 3. Hybrid $ 10.2 million 9 months Costs do not include approach slabs, demolition and mobilization.

Option 1: Least Cost

Option 2: Shortest Schedule

Option 3: Hybrid Concept

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

Alternate 1 Alternate 2 Alternate 3 Bridge $ 500,000 $ 500,000 $ 800,000 $ 800,000 $ 3,600,000 $ 3,600,000 Slope Paving $ 45,000 $ 45,000 $ 0 $ 0 MSE Wall ($ 170,000) ($ 117,000) ($ 1,000,000) Soil Remediation ($ 40,000) ($ 75,000) ($ 600,000) Pavement & Barrier ($ 47,000) ($ 75,000) ($ 334,000) Net Cost $ 288,000 $ 288,000 $ 533,000 $ 533,000 $ 1,666,000 $ 1,666,000 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