Iowa DOT ABC Program Overview, Lessons Learned, Program Direction

slide 1: Accelerated Bridge Construction in Iowa

Ahmad Abu-Hawash, PE
Iowa Department of Transportation
Office of Bridges and Structures

Denver, Colorado
June 5-6, 2012

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None

slide 2: Outlines

ABC/PBES Concept, Advantages, & Disadvantages.
Iowa's ABC Deployment Strategy
Case Study: Keg Creek Lessons Learned

slide notes:

I will briefly talk about the concept of accelerated bridge construction and prefabricated bridge elements and systems, its advantages and disadvantges.
Iowa's ABC deployment strategy
And finally present a case study

slide 3: PBES

Prefabricated Bridge Elements and Systems (PBES): it is a strategy to accelerate bridge construction that employs prefabricated individual Elements such as beam, deck, abutment footing, pier column, pier cap, etc. Or entire superstructure System that is assembled off-site and moved into place.

slide notes:

What is PBES?

slide 4: 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

slide notes:

To deal with schedule constraints such as limited time window due to special events or emergency replacement due to natural disasters, accidents, or intentional acts.
To minimize impact on local traffic by providing access to businesses, commuters, and essential services such as hospitals and fire protection
To deal with the unavailability of suitable detours.

slide 5: ABC: Benefits

Reduced public inconvenience
Improved public perception
Improved road users and workers safety
Reduce negative economic impact on local businesses
Perhaps improve the durability of the structure

slide notes:

The primary benefits of ABC:

Reduced public inconvenience: by not having to go through construction zone or take a detour for full construction season (typically six months or more)
Improved public perception: an example is driving in construction zone on Saturday with traffic restriction and no work being done
Improved road users/workers safety: shorter exposure to construction hazard for both the public and workers
Reduce negative economic impact on local businesses: people try to avoid construction zone therefore local businesses suffer
Perhaps improve the durability of the structure: in the case of precast components fabricated in controlled environment quality is improved

slide 6: ABC: Disadvantages

Substantial increase in construction cost: fewer bridge replacements
Contractors are generally uncomfortable with the PBES concept: higher cost
Requires the development of new design standards and specifications: higher design cost

slide notes:

If you are only considering direct cost, there are definite disadvantages associated with ABC

slide 7: Iowa DOT ABC Deployment Strategy

Develop skills and design details through demonstration projects (IBRD, HfL, SHRP2, ..)
Invest in research and include laboratory and field testing to confirm constructability and performance.
Participate in national pooled fund studies
Involve local construction industry and hold ABC workshops.
Develop policies for ABC

slide notes:

Despite the direct cost disadvantages, there is a definite need for ABC in Iowa.
Keeping in mind that we have to be selective where to use ABC, we needed to develop a deployment strategy.
The first step in the deployment strategy was to Develop skills and design details through demonstration projects.
We took advantage of federal grants such as IBRD, HfL, and SHRP2.

slide 8: Boone County Mackey Bridge

Before and after photos of the Mackey Bridge and a diagram showing a cross-section of the new bridge.

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Boone County Mackey Bridge was the first ABC demonstration project in Iowa using prefabricated components.

slide 9

Two photos showing workers installing precast pier caps and abutment footings.

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Consisting of precast pier caps and abutment footings

slide 10

Two photos showing installed precast prestressed concrete beams and deck panels.

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With precast prestressed concrete beams and deck panels

slide 11: Madison County

Before and After photos and a schematic for a new single-span bridge on local road.

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The second demonstration project was a single-span bridge on local road in Madison County.

slide 12

Collage of photos showing workers installing precast concrete box girders on precast abutment footings.

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Consisting of precast concrete box girders on precast abutment footings

slide 13: Buena Vista County

Before and After photos and a schematic for a new single-span bridge.

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Then we did a second generation single-span total precast bridge in Buena Vista County.

slide 14

Photos of workers installing precast concrete box girders on abutment footings.

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Using precast concrete box girders on abutment footings

slide 15

Photos of workers installing precast wings.

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But this time we included precast wings

slide 16: 24th Street Bridge

Collage of photos depicting an old overpass, artist renderings of a new overpass, and the new constructed overpass.

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Based on the lessons learned from the smaller demonstration projects on the low volume roads, now we are ready for a major interchange project.

slide 17: Overview

Reconstruct the 24th St Interchange over I-80/I-29
Replace existing structure with a two-span CWPG
Use staged construction to maintain one-lane traffic in each direction plus a turning lane
ABC techniques used:
- Full-Depth Precast Deck Panels
- High Performance Concrete and Steel
- Structural Health Monitoring
- Fully Contained flooded backfill
- A+B Bidding
- ITS

slide notes:

The purpose of this major interchange project in Council Bluffs Iowa was to:

Reconstruct the 24th St Interchange over I80/I29
Replace the existing structure a two-span CWPG bridge
Use staged construction to maintain one-lane traffic
The ABC techniques used:

slide 18

Collage of photos of workers performing bridge installation and construction tasks, including lowering precast slabs into place and anchoring the precast elements.

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Here is some of the ABC components used

slide 19: Accelerated Bridge Approach Replacement

Photos of broken concrete chunks and an area on a roadway where the concrete slab has been cut out down to the dirt substrate.

slide notes:

Our demonstration program was not limited to bridges only but we also experimented with precast pavement, primarily for bridge approaches.

Since traditional bridge approach replacement requires up to two weeks of lane closure, accelerated construction makes a lot of sense.

slide 20: O'Brien County Project

Photos of workers installing precast concrete panels.

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The first project was on Iowa 60 in O'Brien County where we used precast concrete panels for the first 75' of each approach

slide 21

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The panels were posttensioned in both directions

slide 22: Bremer County Project

Photos of workers performing installation tasks.

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Unlike the first project, on this bridge approach project on US 65 in Bremer County we required a maximum of 8-hour lane closure at a time and night work

slide 23

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Here is the placement of precast panels

slide 24

Photos specialized construction equipment.

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The contractor showed innovations by building specialized equipment for panel placement

slide 25: Iowa DOT ABC Deployment Strategy

Develop skills and design details through demonstration projects (IBRD, HfL, SHRP2, ..)
Invest in research and include laboratory and field testing to confirm constructability and performance.
Participate in national pooled fund studies
Involve local construction industry and hold ABC workshops.
Develop policies for ABC

slide notes:

Another step in the strategy is to invest in research.

Anytime we tried something new, we included testing components and SHM to confirm constructability and performance.

slide 26: Iowa DOT ABC Deployment Strategy

Develop skills and design details through demonstration projects (IBRD, HfL, SHRP2, ..)
Invest in research and include laboratory and field testing to confirm constructability and performance.
Participate in national pooled fund studies
Involve local construction industry and hold ABC workshops.
Develop policies for ABC

slide notes:

The most cost effective way to do research is through national pooled fund studies

slide 27: Iowa DOT ABC Deployment Strategy

Develop skills and design details through demonstration projects (IBRD, HfL, SHRP2, ..)
Invest in research and include laboratory and field testing to confirm constructability and performance.
Participate in national pooled fund studies
Involve local construction industry and hold ABC workshops.
Develop policies for ABC

slide notes:

And of course involve the local construction industry and hold workshops.

We have very good relationship with the industry in Iowa

slide 28: Iowa DOT ABC Deployment Strategy

Develop skills and design details through demonstration projects (IBRD, HfL, SHRP2, ..)
Invest in research and include laboratory and field testing to confirm constructability and performance.
Participate in national pooled fund studies
Involve local construction industry and hold ABC workshops.
Develop policies for ABC

slide notes:

And the last step is to develop policies for ABC

slide 29: ABC Policies

The policy for ABC implementation is being developed. A target completion date of July 1st.
Assembled a team of engineers from various disciplines to develop the policy with strong support from top management.
The policy will utilize decision making tools such as:
- ABC Rating Score & Flow Chart similar to Utah as a first level filter
- AHP Decision Making Tool as a second level confirmation and further evaluation of alternatives.

slide notes:

None

slide 30: ABC Implementation Barriers

Funding to offset ABC construction cost – need to identify new revenues or alternative funding
Resistance from some local contractors to ABC – working with industry to change the climate
Limited contracting methods – since Design Build (DB) is not allowed in Iowa we are looking at the partial DB option
Design aids – we are working on ABC design policies, specifications and standard details.
Limited experience in ABC design – several ABC projects have been identified to attain experience for our engineers.

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Some of the barriers in the way of ABC implementation

slide 31: Case Study: Keg Creek Lessons Learned

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None

slide 32: Background

SHRP2 – R04 Research Team needed to demonstrate ABC design concept for typical multi-span stream crossings – a common rural bridge replacement
Proposed a demonstration project in Iowa
Successful project may pave the way for developing national ABC standards
A bridge on US 6 over Keg Creek in Pottawattamie County met the objectives

slide notes:

As a part of phase 2 of the SHRP2-R04 project the research team needed to demonstrate the ABC design they developed for typical multi-span stream crossings.
So they proposed a demonstration project in Iowa
A successful project would help pave the way for developing national ABC standards
The bridge on US 6 over Keg Creek in Pottawattamie County met the objectives

slide 33: Project Data

Design: HNTB (M. LaVoilette, B. Sivakumar, F. Hubbard, and K. Price)
Owner: Iowa DOT (D. Evans ∇ Design Review, B. Flippin & G. Feazell)
Testing: ISU (M. Rouse, B. Phares, D. Hartwell, D. Wood, and T. Wipf)
Contractor: Godbersen-Smith (K. Triggs & M. Freier) $2,658,823 (7 bidders from $2.66M to $3.99M)
Unit cost: $231 per sq.ft. ($124 estimated for conventional)
Contract period:
- Phase 1 – Drilled shaft installation (9 working days)
- Phase 2 – ABC Period (14 calendar days)
- Phase 3 – Revetment, grading, and flumes (20 working days)
Incentive/Disincentive on 14 days ABC: $22,000 per day
ABC approximate start date: 9/19/11 (actual 10/17/11)
SHRP2 funds: $250,000 (M. Starnes – Program Officer)
HFL funds: $600,000 or 20% (M. Huie – Program Coordinator)

slide notes:

None

slide 34: EXISTING BRIDGE

Built in 1953
3 spans 53'6",73',53'6"
Moderate sized, typical rural crossing
Small, meandering stream
Narrow bridge width on primary road system
Sufficiency rating 33

Photo of a rural bridge over a stream.
180' x 28'-0 Continuous concrete girder bridge

slide notes:

The existing structure is 180 by 28 continuous concrete girder bridge
Built in 1953
3 span
Typical rural crossing over small meandering stream
It is FO because of the narrow width with sufficiency rating of 33

slide 35: Why Keg Creek?

Typical rural, moderate size stream crossing in Iowa. Indicative of many bridges throughout the mid-west and country. SHRP2 looking to standardize ABC design plans.
Detour: 22 mile detour less desirable for traveling public over 4 to 6 month period versus 2 week ABC period.
Schedule: already programmed for 2011 construction.

slide notes:

Keg Creek was a perfect fit for the R04 project because it is a rural, moderate size stream crossing which is a representative of many bridges in Iowa, the midwest, and the country
Detour length was a factor because anytime you reduce public inconvenience from six months to 14 days is good thing
Schedule: the research team was looking for a project in 2011 and Keg Creek was already scheduled for 2011 construction

slide 36: Why Keg Creek?

Size of bridge favorable for pilot project in term of cost.
Low AADT = ideal for demonstration site.
Narrow existing bridge width allowed for drilled shaft foundation construction prior to bridge closure (outside of ABC).
Bridge geometry: 0 degree skew and flat grade.

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None

slide 37: AHP Analysis

Graph and pie chart showing elements addressed in AHP analysis.

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None

slide 38: 14-Day ABC Timeline

(as proposed by the Contractor)

Keg creek project schedule for the planned 14 day closure from September 28 thorugh October 11.
Actual ABC period: October 17 – November 1

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None

slide 39: Iowa Bridge Farm

(Phase 1)

Aerial photo of the facility used to make precast elements, with the locations where column casting, reinforcing steel cage assembly, modular deck casting, and abutment stem and wing casting identified on the photo.

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None

slide 40: Precast Substructure Components Casting

(Phase 1)

Photos of precast substructure components.

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None

slide 41: Superstructure Modules – Structural Steel Assembly

(Phase 1)

Collage of photos of the structural steel assembly.

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None

slide 42: Superstructure Modules – Deck Forming

(Phase 1)

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None

slide 43: Deck Concrete Placement

(Phase 1)

Photos of the deck concrete placement process.

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None

slide 44: Drilled Shaft Construction

(Phase 1)

Photos of the drilled shaft construction process.

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None

slide 45: Abutment / Wing Erection

Photos of workers erecting the abutment and wings.

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None

slide 46: Pier Details

Construction schematics for the bridge piers.

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None

slide 47: Pier Connection Details

Construction schematics and photos of the bridge pier connections.

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None

slide 48: Column Assembly

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None

slide 49: Bedding and Coupler Grouting

Photos of workers preparing the bedding and conducting coupler grouting activities.

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None

slide 50: Cap Beam Assembly

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None

slide 51: Modular Superstructure Details

Schematic of the modular superstructure.

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None

slide 52: Superstructure Module Transport

Photos of the superstructure module being transported and placed.

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None

slide 53: Module Assembly

Photos of the superstructure module being installed.

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None

slide 54: Module Assembly

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slide 55: Final Module Placement

Photos of the final module being installed.

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None

slide 56: Precast Approach Slab Details

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None

slide 57: Flooded Backfill System

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None

slide 58: Precast Approach Preparation

Photos of workers preparing to place the precast approach.

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None

slide 59: Precast Approach Slab Placement

Photos of workers placing the precast approach slab.

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None

slide 60: UHPC Placement

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slide 61: Completed Bridge

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slide 62

A balloon light illuminates the workzone on October 17, 2011.

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slide 63: Conclusions

ABC design concept was successfully demonstrated but there were some challenges along the way.
Post construction review identified problem areas, as expected, and provided recommendations for improvements which will be documented in the final report.
As the result of this project (and other past ABC projects), Iowa DOT gained a better understanding of risks and benefits associated with ABC and is developing ABC policy.

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slide 64: Questions?

Project Website: http://www.iowadot.gov/us6KegCreek/

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