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Albuquerque bridge is first to have built-in fiber-optic sensors

A new bridge over the Rio Puerco west of Albuquerque will be the first of its kind in the nation with built-in fiber-optic sensors to monitor stress in the bridge's girders.

Known as "smart bridge" technology, the self-monitoring system offers many advantages over methods that rely largely on visual inspections, said New Mexico State University civil engineering professor Rola Idriss.

Idriss previously has retrofitted an Interstate 10 bridge in Las Cruces with fiber-optic sensors as part of her smart bridge research. The Rio Puerco bridge, being built for an Interstate 40 frontage road about 15 miles west of Albuquerque, is the first U.S. bridge to have this type of monitoring system built into the girders, Idriss said.

"This is a really interesting project, because it is so practical," she said. "The data will be immediately useful, from the time the concrete is poured for the girders, as they are transported to the site, during the construction of the bridge, and while it is in service."

The bridge also will be the first in New Mexico to utilize high-performance concrete, said Bryce Simons, state concrete engineer for the New Mexico Highway and Transportation Department. The built-in monitoring system will provide data for assessing the performance of the concrete, which is expected to withstand heavier loads and last longer than ordinary concrete, he said.

For bridge safety monitoring, the use of fiber-optic sensors can provide information on the effects of stress long before signs of fatigue begin to show visibly, allowing engineers to address potential problems before they become serious and costly, Idriss said.

Data from such systems can be downloaded on-site, which will be the case for the Rio Puerco bridge, or transmitted to a remote location. The monitoring system that Idriss installed on the I-10 bridge in Las Cruces transmitted data by cellular telephone to her computer on the NMSU campus.

The Rio Puerco bridge monitoring project is being funded by the state Highway and Transportation Department, the Federal Highway Administration and the National Science Foundation. Collaborating on the project is the University of New Mexico, which is involved in testing the high-performance concrete.

Johnny Gallegos, project manager for the Highway and Transportation Department, said the installation of the fiber- optic instrumentation and the pouring of concrete for the girders is scheduled to take place during the week of July 17. The bridge construction is expected to be completed by the end of the year, he said.

CSR Albuquerque Pre-Stress is doing the concrete work. The bridge contractor is A.S. Horner Inc.

Karl Hill
July 17, 2000