From federal and state transportation departments to universities, engineering firms, and industry suppliers, transportation-focused research is developing the future design methods and materials that will help rebuild America’s infrastructure. The active programs and research projects are too numerous to summarize here; however, based on a selection of research abstracts and published reports, the following are brief descriptions of some of the research projects under way across the country.
The U.S. Department of Trans-portation’s Research and Innovative Technology Administration (RITA) sponsors a wide range of transportation research, providing $81 million annually to 136 colleges and universities conducting transportation research and providing training to manage today’s transportation infrastructure. Since mid-August, RITA has awarded $41.7 million in grants to 26 University Transportation Centers (UTC). More information about the UTC program is available at http://utc.dot.gov.
Listen here to an interview with Peter H. Appel, administrator of the Research and Innovative Technology Administration.
Another federal program, the Federal Highway Administration’s (FHWA) Exploratory Advanced Research (EAR) Program (www.fhwa.dot.gov/advancedresearch), focuses on long-term, high-risk research that is judged to have a high payoff potential. Current projects include the following:
The Utah Department of Transportation (UDOT) initiated a three-phase study of glass fiber reinforced polymer (GFRP) reinforcing bars used as an alternative to steel rebar in bridge decks. Two GFRP-reinforced precast concrete deck panels were monitored during construction, lifting, and placement using electrical strain gauges and during post-tensioning, truck load testing, and long-term performance using vibrating wire strain gauges. The rural bridge opened to traffic on Oct. 2, 2009; long-term monitoring continues with a second static and dynamic truck load test planned for the future.
Following years of research, Applied University Research Inc. (AUR; www.noscour.com) announced development of patent-pending scAUR and VorGUAR precast concrete components that attach to bridge piers and abutments to eliminate the types of flow that cause local scour. Product shapes are optimized for each bridge pier or abutment, the company said, and manufactured in sections that interlock during installation.
In another project focused on bridge scour, Xiong Yu, an assistant professor of civil engineering at the Case School of Engineering, is designing underwater sensors that relay real-time information about how much of the river bottom has been stripped away and how stable, or unstable, the supports of a bridge remain. Yu’s lab built sensors comprised of micro pillars made with piezoelectric fibers mounted on flexible copper rods. The fibers produce electric signals reflecting flow direction and speed. Additionally, to determine the amount of sediments being scoured away, his lab has built sensors that constantly measure the topography where the water meets the river bottom around the bridge supports. The sensors proved durable, sensitive, and accurate when tested on bridge supports 10 to 20 feet below the surface. The next step is to determine the maximum depth and flow conditions under which the sensors provide accurate and immediate information.
Researchers from BergerABAM Inc. and the University of Washington recently reported on a fully precast bridge bent suitable for use in seismic regions. Lateral load tests on the column-to-cap and column-to-footing connections demonstrated that the connections have strengths and ductilities similar to those of comparable cast-in-place connections. Construction of a demonstration bridge project was expected to begin this year. Information is available at www.fhwa.dot.gov/hfl
Following initial design of the 4,032-foot-long U.S. 378 bridge over the Great Pee Dee River in Marion and Florence Counties, S.C., consulting engineers Florence & Hutcheson (F&H) evaluated the use of prestressed concrete cylinder piles as an alternative foundation type. The firm determined that 54-inch prestressed cylinder piles were a viable option and devised a testing program to evaluate installation and capacity of both 54-inch cylinder piles and drilled shafts. The testing program, performed prior to construction, allowed the findings to be incorporated into the construction plans, resulting in more cost-effective bids for the bridge replacement, F&H said.
The U.S. Army Corps of Engineers recently released an inspection report focused on one of two Recycled Structural Composite (RSC) bridges constructed last year for the Department of Defense at Fort Bragg, N.C. The report, “Field Testing and Load Rating of the World’s First Thermoplastic Bridge,” incorporates data culled from 57 strain transducers and seven vertical displacement sensors that have been in operation since the bridge was dedicated in September 2009. Tests were conducted first by driving 36-ton dump trucks and later 72-ton M1 tanks over the bridge. Axion International developed RSC bridge components in conjunction with Rutgers University’s Materials Sciences and Engineering Department. Copies of the report are available at www.axionintl.com
The Vermont Agency of Transportation (VTrans) initiated performance monitoring of jointless bridges — often called integral abutment bridges — to gain an understanding of how they respond to thermal movements and to dead and live loads in a northern climate. The goal is to provide VTrans engineers with the knowledge and quantitative data to design and construct cost-effective, efficient, safe, reliable, and low-maintenance structures. Final research findings, expected in February 2013 when the University of Massachusetts-Amherst completes the third phase of the monitoring project, will serve as the foundation for revisions to the design guidelines and development of design standards for integral abutment bridges.
Road and pavement research
A partnership between the Western Transportation Institute, the Montana Department of Transportation, and the U.S. Department of Transportation’s RITA is working to develop and characterize portland cement concrete suitable for transportation-related applications in which a portion of the conventional aggregate has been replaced with reclaimed asphalt pavement (RAP). Research will focus on the durability characteristics of using RAP in portland cement concrete and will begin by developing mix designs with strengths, set-times, and workability similar to conventional concrete mixtures. Once these mix designs are developed, the resulting concretes will be evaluated with a suite of mechanical and durability tests. Research is expected to be completed in July 2011.
Iowa State University researchers are testing Bioasphalt — asphalt containing bio-oil — on a paved bicycle trail in Des Moines. Bio-oil is created by a thermochemical process called fast pyrolysis in which corn stalks, wood wastes, or other types of biomass are quickly heated without oxygen. The bike trail used an asphalt mix containing 5 percent Bioasphalt. If successful, researchers plan to increase the percentage of Bioasphalt in future pavement tests.
Collaborative research between the North Carolina State University Department of Civil, Construction, and Environmental Engineering and the North Carolina Department of Transportation (NCDOT) is evaluating warm-mix asphalt technologies for NCDOT mixes (See page 17 for more information on warm-mix asphalt). Studies will evaluate the moisture sensitivity of the mixes at the design asphalt content; rutting performance; material performance characteristics for rutting and fatigue; and determine any benefit in cost savings associated with lower energy consumption in relation to warm-mix asphalt’s performance.
The Transportation Research Board’s National Cooperative Highway Research Program Report 663: “Design of Roadside Barrier Systems Placed on MSE Retaining Walls” explores a design procedure for roadside barrier systems mounted on the edge of a mechanically stabilized earth wall. The procedures were developed by researchers at Texas A&M following American Association of State Highway and Transportation Officials Load and Resistance Factor Design practices.
The University of Vermont Transportation Research Center is seeking to characterize the suitability of porous concrete pavements in northern climates. The project will focus on basic mix designs and the effects of freeze-thaw, wear and tear, and winter maintenance on porous pavement systems. Evaluations include the strength, durability, and hydraulic conductivities of the materials. Researchers expect to develop a numerical model for the overall system — pavement, subgrade, and subbase.
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