Iowa Falls Steel Arch

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Iowa Falls Steel Arch
Project Overview

• Hussein Khalil, P.E.

Iowa ABC Workshop, August 11-12, 2008 Des
Moines, Iowa
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Iowa Falls Steel ArchProject Location
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Iowa Falls Steel Arch
Project Description

• Replace a 255 x 24 Open Spandrel Concrete Arch
  with a 230 x 64 Partial Thru Steel Arch
• Existing bridge and a nearby church are on the
  National Register of Historic Places
• Difficult site conditions (vertical limestone
  banks)
• Environmentally sensitive area
• Existing sewer lines directly below the structure
  

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Existing
Proposed
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Iowa Falls Steel Arch

• Limits of Construction

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Iowa Falls Bridge

• Typical Cross Section

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Iowa Falls Steel Arch
Project Background

• Need for Project
• Existing Bridge is Structurally Deficient
• No Practical Long Term Rehabilitation Options
• Traffic Estimates
• Year 2011 11,000 ADT with 8 Trucks
• Year 2031 15,400 ADT with 8 Trucks

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Iowa Falls Steel Arch
Project Background

• Feasibility study alternatives considered
• Single Span Steel Arch
• Single Span concrete Deck Arch
• Two Span Prestressed Girder Bridge
• City of Iowa Falls and Historical Commission
  Requested the Bridge Be Replaced with an Open
  Spandrel Bridge with Decorative Railings,
  Walkways, and Lighting

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Iowa Falls Steel Arch
Project Background

• Special Considerations
• St. Matthews by the Bridge Episcopal Church
  Listed in the National Register of Historic
  Places and Located about 20 West of the North
  End of the Bridge.
• Construction Vibration Concerns.
• Two Sanitary Sewer Lines
• Recommended that These be Replaced and Relocated
  Prior to Bridge Construction
• Dam Located Downstream of Bridge
• May Allow Lowering Water Level to Facilitate Some
  Construction Activities with Approval from DNR

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Iowa Falls Steel Arch
Session Objectives

• Identify accelerated construction methods to
  complete removal and replacement in one
  construction season
• Avoid demolition/construction related vibration
• Protect existing sewer lines (debris not allowed
  to fall into the river)
• Evaluate the use of temporary falsework or/and
  barges