ACCELERATED BRIDGE

Photo Credit: Iowa DOT

constructionBY JOHN E. POWELL, JR. & BENJAMIN BEERMAN

The State of Our Highways & Bridges:

Copyright © 2012 by the Construction FinancialManagement Association. All rights reserved. Thisarticle first appeared in CFMA Building Profits.Reprinted with permission.

From coast to coast, bridges connect the intertwining rib-bons of our national transportation network in a safe and efficient manner.

While the average motorist may be aware of the heavy loads and high traffic volumes that our bridges carry, most might not consider how many of these bridges exist, what it takes to maintain them, and more importantly, how the work to keep them maintained can impact our nation.

The U.S. is challenged by an aging infrastructure and increasing traffic volumes. Consider the following:

• Transportation for America reports that almost 70,000 bridges in the U.S. are classified as “‘structurally defi-cient,’ requiring significant maintenance, rehabilitation, or replacement.”

• The average age of an American bridge is 42 years, and the expected lifespan of most bridges is 50 years.

• Nearly 200,000 of the roughly 600,000 highway bridges are 50 years old or older, and by 2030, that number could double.1

In response to these ever-increasing needs, transportation agencies throughout the U.S. strategically perform the re-quired maintenance, rehabilitation, and replacement activities to maintain the integrity of our transportation network and the safety of the traveling public.

However, as the country’s departments of transportation carry out their duties, the mobility of this network becomes reduced due to the work zones that are created.

Whether traveling through the Fort McHenry Tunnel or the towers of the Golden Gate Bridge, it is

easy to take for granted all the benefits and efficiencies the U.S. transportation network provides

to our nation – both for personal use and for the many businesses that use it to transport goods.

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Take for example our current National Highway System (NHS). With more than 160,000 miles of roadway, it only rep-resents about 4% of the nation’s roads, yet carries 40% of the traffic and 75% of heavy truck traffic. A 2003 Federal Highway Administration (FHWA) report revealed that in 2001, there were an estimated 3,110 highway work zones on the NHS dur-ing the summer months, which corresponded to more than 20,000 miles of roadway – or a 12.8% reduction in capacity.

These reductions can result in traffic congestion, which in turn impacts productivity and reduces quality of life. Based on the Texas Transportation Institute’s 2007 Urban Mobility Report on the 437 urban communities located throughout the U.S., congestion causes:

• 4.2 billion hours in time delays per year

• 2.9 billion gallons of wasted fuel per year

• $78.2 billion in cost to travelers (based on 2005 gas prices)2

Every Day Counts Initiative

To better help address these increasing needs, the FHWA rolled out a series of initiatives under the purview of the “Every Day Counts” (EDC) initiative in 2010.

The EDC program is a collaborative effort among the FHWA, the American Association of State Highway and Transportation Officials,3 state departments of transportation, local agencies, and other industry members to reduce overall project delivery time frames.

Because our mature transportation network is continually being used, highway and bridge construction techniques have to undergo a paradigm shift from conventional construc-tion methods in order to make a meaningful dent in these timelines. However, the work activities that are required to maintain it must be carried out in a manner that minimizes the disruptions to traffic.

To help the departments of transportation, bridge authori-ties, and other agencies quickly become familiar with inno-vations that can help address this need, the EDC program provides a national focus on certain technologies and innova-tions that have been successfully used in the past.

By increasing the awareness of these methods on a national level, departments of transportation can build upon each oth-ers’ experiences, resulting in increased implementation and continual refinements of the concepts being used.

Some process-based EDC initiatives include planning and procurement strategies that provide greater flexibility for permitting, right-of-way acquisition, and utility relocation, which can help clear a site prior to the start of any major bridge construction activity.

A technology-based initiative promoted through the EDC program is prefabricated bridge elements and systems (PBES), which can enable the onsite aspects of bridge construction to be performed in a safer and more efficient manner.

What Is PBES?

PBES is an accelerated bridge construction (ABC) technol-ogy that comprises the structural components of a bridge built off-site or adjacent to the existing highway alignment. It includes features that reduce onsite construction time and mobility impact time compared to conventional construction methods.

Examples of prefabricated elements include decks, beams, piers, and abutment and walls. Prefabricated systems consist of an entire superstructure, superstructure and substruc-ture, or bridge that, once placed, allows traffic operations to resume soon afterwards.

Benefits

PBES is a key enabling technology that reduces overall proj-ect delivery time when combined with additional ABC tech-nologies (such as high-early strength concrete for closure pours for precast bridge element connections, horizontal bridge slides to place complete bridge systems into place, or grouted coupler connections that are embedded in precast columns, footings, cap beams, or pile shafts to complete permanent connections).

Bridge projects that have traditionally taken one, two, or more construction seasons to complete can be completed in weeks or weekends.

PBES can also address differing site constraints, improve worker and public safety, and reduce liability exposure from traffic accidents in the work zone. Improvements in quality can also be realized because the bridge components are built off the critical path and under controlled environmental conditions.

For example, when concrete is poured onsite, restraint of concrete can occur, which is when concrete that is poured adjacent and connected to previously poured concrete

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shrinks and the previously poured concrete does not, lead-ing to internal tensile stresses that can ultimately cause cracking during the cure. Precast concrete elements have significantly less cracking than site-cast concretes.

Using the most current full-year data from 2010, fatalities in motor vehicle traffic crashes in work zones were 576.4 By using Self-Propelled Modular Transporter (SPMT) bridge moves, horizontal slides, longitudinal launches, and other heaving lifting equipment and methods, lives could be saved, injuries avoided, and costs reduced with less frequent pub-lic construction interfaces. (See ABC Structural Placement Methods on the last page for more information.)

Because of its adaptability to address differing site con-straints, the efficiencies realized with onsite construction, improvements in safety, and the intrinsic benefits in quality that PBES can offer, the FHWA’s goal is for PBES to become the preferred method of bridge construction.

Cost faCtors to Consider

Total project costs are a function of many factors, including:

• Terrain

• Design options

• Proximity to precast plants (if off-site fabrication is considered)

• Traffic flow

• Material and labor availability

• Urgency of work

• Type of work

• Familiarity with key regional suppliers and contractors

Measuring suCCess

Financial success is often the lead metric in determining the success of a project; however, public perceptions can also communicate a loud and clear message to public officials.

For example, the Utah Department of Transportation (UDOT) has led the country in ABC after its need to rapidly expand its transportation infrastructure to host the 2002 Winter Olympic Games in Salt Lake City. Since then, ABC has been Utah’s pri-mary way of rehabilitating, redesigning, and building bridges.

Every year, UDOT surveys the public’s satisfaction of road-way projects conducted in the state. In previous surveys, UDOT typically found that one-third of respondents were satisfied, one-third did not care, and one-third were not satisfied. The 4500 South Bridge project, which was built in an accelerated manner using PBES technologies, tells a dif-ferent story: Of the 71 respondents that were surveyed, 94% were satisfied with the project.5

Case study: the i-85 Bridge

When the car company Kia was building a manufactur-ing plant that would bring 6,000 workers to the area, the

Photo Credit: Iowa DOT

ACCELERATED BRIDGE

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November/December 2012 CFMA Building Profits

Photo Credit: Iowa DOT

Georgia Department of Transportation (GDOT) used PBES to reduce the time and cost of construction on the I-85 bridge in Troup County, GA.

On this project, use of prefabricated pier columns and caps was selected. If GDOT had used conventional bridge con-struction practices, then the project would have required 30 months to complete; by using PBES technologies, GDOT was able to complete the project in 16.5 months.

GDOT also found that using PBES improved safety and increased traveler satisfaction. In terms of costs, the state was able to save $1.98 million – or 45% – of what the inter-change would have cost if it had been built with conventional construction practices.

Because the prefabrication technologies and processes allowed for the pier elements to be constructed off-site and away from traffic, there were fewer disruptions to traffic, leading to safety improvements for both the contractor’s personnel and the traveling public.

Conventional construction practices would have increased trip time by 25%, but GDOT found that travel delays using PBES were rare. When they did occur, they were typically less than 90 minutes. Scheduling deliveries and construction activities during nonpeak traffic hours further minimized lane closures and inconvenience to the traveling public.

Coming to a Bridge Near You

With ABC, partial or complete bridge moves can be done with quality and efficiency. Contractors that continue to solely pursue conventional work will still have access to jobs, but over time may experience limited growth opportunities. Adopting more robust planning processes will facilitate suc-cess in ABC implementation, and the benefits of reduced job time frame, safety improvements, and quality enhancements make the process worthwhile. n

Endnotes:

1. “The Fix We’re In For: The State of Our Nation’s Bridges,” Transportation

for America, March 30, 2011, t4america.org/docs/bridgereport/bridgere-

port-national.pdf.

2. Schrank, David & Lomax, Tim. “The 2007 Urban Mobility Report,”

Texas Transportation Institute, The Texas A&M University System,

September 2007, www.pagnet.org/documents/HumanServices/Mobility

Report2007Wappx.pdf.

3. www.fhwa.dot.gov/everydaycounts/about.

4. Fatalities in Motor Vehicle Traffic Crashes by State and Work Zone

(2010), The National Work Zone Safety Information Clearinghouse, www.

workzonesafety.org/crash_data/workzone_fatalities/2010.

DON’T MISS ABC Structural Placement Methods

on the following page

CFMA Building Profits November/December 2012

5. FHWA Utah Demonstration Project: Rapid Removal and Replacement

of the 4500 South Bridge over I-215 in Salt Lake City User Satisfaction

Survey.

6. “Manual on Use of Self-Propelled Modular Transporters to Remove and

Replace Bridges,” Chapter 2, Sec. 2.3.1, U.S. Department of Transportation

Federal Highway Administration, June 2007, www.fhwa.dot.gov/bridge/

pubs/07022/chap02.cfm#s22.

7. “Dish soap to help slide I-15 bridges in place in Mesquite.” The Associated

Press, 10 Jan 2012, www.standard.net/stories/2012/01/10/dish-soap-

help-slide-i-15-bridges-place-mesquite.

JOHN E. POWELL, JR., CPCU, ARM, ARe, ALCM, CRIS, is a Senior IndustryEdge Director – Construction at The Travelers Companies, Inc. in Hartford, CT. In this role, Jack serves as industry director for guaranteed cost construction business segments involving heavy and trade classes.

Jack has more than 30 years of experience in construc-tion marketing, workers’ comp reinsurance, commercial business development, underwriting, and risk control. He has presented at regional peer-to-peer exchanges on the FHWA’s “Every Day Counts” program.

A member of CFMA for nearly 10 years, Jack served on the local Connecticut Valley Chapter Board and previ-ously served as a national At-Large Director for four years.

Phone: 860-277-6649 E-Mail: jepowell@travelers.com Website: www.travelers.com

BENJAMIN BEERMAN, PE, is a Senior Structural Engineer with the U.S. Department of Transportation, Federal Highway Administration in Atlanta, GA, where he serves as the national deployment coordinator for the promotion and use of prefabricated bridge elements and systems for Accelerated Bridge Construction projects under the purview of the “Every Day Counts” initiative.

Previously, Ben worked for the West Virginia Division of Highways, where he held a dual position as a Consultant Coordinator and Squad Leader. He began his career at the Louisiana Department of Transportation while attend-ing graduate school.

Ben holds a BSCE in Civil Engineering from Louisiana State University. He is a member of the American Social of Civil Engineers, American Society of Consulting Engineers, Mid-Atlantic Committee for Economical Steel Fabrication, and the Mid-Atlantic Committee for Economical Prestressed Concrete.

Phone: 404-562-3930 E-Mail: benjamin.beerman@dot.gov

Website: www.fhwa.dot.gov

The accelerated bridge process uses three major methods of placing the components or entire bridge, also known as structural placement methods. The most impressive method is Self-Propelled Modular Transporters (SPMTs). Although they are massive in size, their computer-con-trolled synchronized movements resemble that of a ballet dancer. SPMTs are capable of moving entire bridges, rotat-ing them, and then lifting them into place with precision.

The total initial cost for using SPMTs can range from $50,000 to more than $500,000, depending on the job loca-tion and requirements.6 While that may seem like a large expense, the ability to work away from traffic in a setting that may present less of an environmental footprint may be worth it. The equipment may need a substantial staging area, so thoughtful advanced planning is required. The use of SPMTs can offset the need for temporary roads, median crossover diversions, and other methods used with con-ventional construction.

Another choice for total bridge moves is the “horizontal slide” (also called horizontal skidding or lateral sliding/skidding), where the new superstructure is built in its entirety immediately adjacent to the structure to be re-placed. When the bridge is complete, the road is typically closed over the course of a weekend. In that time, full demolition precedes sliding the new structure into place.

At a project on I-15 in Mesquite, NV, last January,7 Dawn® dish soap was used to lubricate the Teflon rails that served as the tracks for the horizontal movement. No SPMT was needed as job circumstances allowed replacement to be built on grade with the final position. By Sunday night, the new overpass was in place with new approach pavement and was ready for traffic.

A third technique for component placement is a horizontal launch that uses a variety of configurations. Using a lon-gitudinal gantry frame, deck sections are received, lifted, and transported to the exact placement site overhead.

ABC Structural Placement Methods

ACCELERATED BRIDGE

construction

November/December 2012 CFMA Building Profits