Improving bridge inspections: researchers at FHWA are developing innovative nondestructive evaluation technologies to assess the condition of bridges

Public Roads, Nov-Dec, 2003 by Glenn A. Washer

In addition, the inspectors performed two indepth inspections, defined as up-close, arms-length inspections generally conducted to identify deficiencies not normally detected during routine inspections. One indepth inspection involved evaluating a welded steel girder with fatigue-sensitive details. The inspectors were expected to search for and find seven crack indications on a specific portion of a steel bridge. Inspectors reported the crack indications at a rate of 3.9 percent. About 4 out of every 100 inspections of a particular crack indication correctly identified the indication. Test results indicated that 86 percent of the inspectors who correctly identified the indications used a flashlight for the inspection and were on average 0.2 meter (0.7 foot) from the girder during the inspection. Among inspectors who did not correctly identify indications, only 38 percent used a flashlight, and the inspectors averaged 2.7 meters (8.9 feet) from the girder during the inspection.

These results indicate that the low crack-detection rates found during the study may be related to how the inspections are performed,

nents from a traveling erection platform. The 104 pile caps are identical except for the length and number of conical holes (two or three) for integration with the steel pipe piles. Shear keys between panels and the reinforced concrete overlay are the only cast-in-place concrete. Traffic barriers were slip-formed.

What Needs to Change?

These accelerated prefabricated bridge projects illustrate a change in thinking from the traditional approach to a systems approach that considers traffic impacts during the planning stage.

"Contracting procedures need to change to provide incentives for contractors to build bridges rapidly," Dick observes. "Whether it's A plus B bidding or other incentive/disincentive programs, the system has to change to encourage innovation."

"To be cost-effective," Rick Lawrence, president of Lawrence Construction Co. from the Colorado project, adds, "I need to build at least 10 bridges at a time, but the State awards projects one at a time." By grouping single-span bridges, both the contractor and the State would realize volume savings in materials and labor. Another option is the design/build approach enabling the contractor to contribute practical ideas for accelerating construction.

Although the States have reaped the rewards of accelerated construction and superior quality with components produced in a controlled environment, some details of this technology can still be improved. Kerley cautions, "My concern is not with the quality of the components but with the quality of the connections."

Saad agrees, "We still need research on developing the best practices for delivering this technology."

Ian Friedland, FHWA bridge technology engineer adds, "Some standards and specifications need to be evaluated for accelerated construction."

Looking to the future, Kerley says, "Through the AASHTO TIG we're establishing a network in which one State shares its success, and another State takes the idea and tweaks it for its project."