Examining bridges: setting new standards for bridge inspections

Robert Connor, the Jack and Kay Hockema Professor in Civil Engineering, collaborated on research for the report "Proposed Guidelines for Reliability-Based Bridge Inspection Practices" under the National Cooperative Highway Research Program (NCHRP).

A Lyles School of Civil Engineering professor's research is helping shape how bridges are inspected across the nation

Robert Connor, the Jack and Kay Hockema Professor in Civil Engineering, collaborated on research for the report "Proposed Guidelines for Reliability-Based Bridge Inspection Practices" under the National Cooperative Highway Research Program (NCHRP).

The research, which was completed six years ago, came up when the results were cited in the newly proposed National Bridge Inspection Standards (NBIS) under consideration by the U.S. Department of  Transportation's Federal Highway Administration. The NBIS effectively governs how and when highway bridges are inspected in the United States.

"The results of the research will allow the intervals at which bridges are inspected to be established based on a risk-based approach," Connor said. "It's a compliment to see your work have a potentially major impact."

The NCHRP research cited in the proposed bridge inspection standards followed initial work Connor conducted for the Federal Highway Administration that developed risk-based inspection strategies for bridges that contain non-redundant steel tension members known as fracture critical members.

Robert Connor
Robert Connor

Connor said current bridge inspection standards are calendar-based, calling for on-site inspections every 24 months, whether it’s a new bridge or 100-year-old bridge. There are no explicit adjustments for age or circumstances such as environmental conditions that can wear on a bridge faster.

Connor said the research report cited in the proposed inspection standards calls for a risk-based analysis that allows inspection efforts to focus on bridges and areas that are more likely to have problems or would have significant consequences should a problem arise.

"The research allows an owner to decide how to best manage the inspection needs of their diverse inventory of highway bridges," said Connor, director of the Steel Bridge Research, Inspection, Training and Engineering Center.

"Rather than over-inspecting newer, healthy bridges, the interval can be rationally extended to every 48 or 72 months for some," he said. "This will then allow an owner to spend more time on other bridges they are more concerned about and inspect those every 12 months, for example."

Connor was co-principal investigator in the research as part of a team of colleagues including Glenn Washer, a professor of civil and environmental engineering at the University of Missouri, who approached him for the project.