Pueblo at Center Stage

By William J. Angelo

Newly engineered first composite rail bridge undergoes successful testing

What industry experts believe is the world’s first composite railroad bridge is now being tested in Colorado. Work also is under way to make the technology standard on highway bridges.

HC Bridge Co. LLC of Chicago successfully tested a 30-ft-long, 17-ft-wide span comprised of eight hybrid composite beams this winter. It supported a full-size locomotive pulling 26 heavy-axle-load coal cars. The test was conducted at the 2.7-mi-long Facility for Accelerated Service Testing loop at the Transportation Technology Center near Pueblo. The center is owned by the Federal Railroad Administration but operated by a subsidiary of the Association of American Railroads. Five of its members financed the test.

“The test cars weigh about 315,000 lb each. Typically, most cars weigh about 286,000 lb or less,” says Duane Otter, principal engineer with Transportation Technology Center Inc., a subsidiary of AAR. “This composite beam proved successful and behaved as predicted in terms of measured strains and deflections.”

Static loads were provided by parking rail cars at various points on the bridge. A short train then traversed the bridge at speeds up to 45 mph. Finally, testers ran 47 passes with additional cars. “Key measurements were taken using string potentiometers at mid-span of each of the eight beams,” says Otter. “We also had strain gauges post-installed in the beams on the arch, and gauges on the deck and on the bottom side of the beams.”

Following the test, the track was removed and the deck and beams inspected. The bridge is intended to have a life span of 80 to 100 years. Otter notes that second-phase endurance testing could take up to a year and start in late summer. If all goes well, beams will be placed for more monitoring in revenue service locations along the network of North American Class 1 railroads that include some 9 million ft of bridge.

John R. Hillman, founder and president of HC Bridge, designed the patented Hillman-Composite Beam to be stronger, lighter and more corrosion-resistant than concrete or steel beams. Its glass-fiber-reinforced plastic shell contains self-consolidating concrete pumped into a 4-in.-tall void to provide compression reinforcement and high-strength continuous steel fibers placed along the bottom flange of the beam shell, anchored by 90° bends, to provide tension reinforcement.

“It’s a highly efficient reinforced-concrete beam where 90% of the strength and stiffness comes from concrete and steel components,” says Hillman. When the bridge is subjected to loads, the concrete is in compression and the steel is in tension.

Plans are in the works for testing the composite beam on two highway bridges this year. The first is a 58-ft-long span in Lockport Township, Ill. The second is a 31-ft-long span in Cedar Grove Township, N.J. “The success of the HCB could result in a paradigm shift in the bridge industry,” claims Hillman.

All testing will be conducted at a composites center at the University of Maine, Orono. Composite bridge beams will be fabricated by Harbor Technologies, Brunswick, Maine.

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