A full-size locomotive pulling 26 heavy-axle-load coal cars has traversed the world's first composite railroad bridge, opening up the possibility that the corrosion-resistant material is just as viable an option as concrete and steel beams for highway bridges.
The live load test was conducted on a 2.7-mile testing loop near Pueblo, Colo., a transportation research and testing facility operated by Transportation Technology Center Inc. (TTCI), a subsidiary of the Association of American Railroads.
The bridge's 30-foot span is composed of eight hybrid-composite beams made of three subcomponents:
- Compression reinforcement—self-consolidated concrete that is pumped into a profiled conduit within the beam shell
- Tension reinforcement—steel reinforcing fabrics consisting of thin, twisted, 450,000-psi high-tensile steel cords that run along the bottom flanges of the beams.
“When we started using prestressed concrete 50 years ago, it was considered a new technology,” says Duane Otte, a principal engineer with TTCI. “We see the technology as having the potential to become a new mainstay.”