The Dizzying Heights of Bridge Inspection

With a terrain of hills, valleys, and three rivers, Pittsburgh relies on its many bridges for moving traffic throughout the region. Keeping those bridges safe and up to federal regulations for National Bridge Inspection Standards requires rigorous and consistent inspection.

In this first of a three-part series, GAI Transportation Technical Manager Mike Beresford, PE, CBSI and Senior Project Engineer Brad Kughn, PE, CBSI tell us what it’s like to inspect bridges—from climbing dizzying heights to closing a bridge in the middle of the night.

What’s it like to be up in the air on a bridge?

Brad: It’s exhilarating, but I try not to think about it too much. We both have performed inspections using access equipment like ladders or structural rigging, and inspection access vehicles like lift buckets or under bridge inspection cranes. Regardless of the access method, in most cases we are pretty high in the air. Even when we’re underneath the bridge, we can still be pretty high up.

Bridge inspection of a pedestrian bridge at Ohiopyle State Park in Mill Run, PA takes experience, skill, and courage.

Mike: Brad is more courageous than I am when it comes to working at heights. I prefer the confines of an inspection access vehicle with an inspector basket I can’t fall out of, fully supported and secured with a safety line. But Brad does a lot of “free-climbing” using first-man-up technology that uses safety lanyards and safety lines to maintain a 100 percent tied-off condition. He has inspected 200-foot radio towers and the Mon Incline…stuff that’s really outside my comfort zone. It definitely can be a dangerous job. There’s no room for a fear of heights and requires physical strength and a lot of concentration.

How do you start a bridge inspection project?

Mike: We first review the previous inspection report to understand the type and condition of the structure. Then we plan for gaining inspection access—either from the top or from the bottom, whether the bridge crosses a road, waterway, or railroad. We might have to subcontract an inspection access firm to supply a crane, bucket truck, or ladders to access the structure. With an inspection involving a railroad, coordinating inspection access and right-of-entry permitting may take several months before the inspection.

How long does an inspection take after all the planning is in place?

Brad: If it’s a routine inspection, a week or a week and a half for larger structures. It all depends on the makeup of the structure. Some structures that we inspect have special details or conditions that require additional effort. For example, if the bridge is classified as fracture-critical, we have to apply a formal Fatigue and Fracture Inspection Plan so as to carefully look at every fatigue prone detail on each fracture critical member, document any cracking, and prepare a Plan-of-Action to address immediate areas of concern. That increases time considerably.

On the other hand, with our locally owned bridge inspection efforts, we may inspect three or four small bridges per day if they are only 20 or 30 feet in length and we can access them from the ground or using just a ladder.

Bridge Inspection
Inspecting bridges, radio towers, or inclines often puts the inspectors in precarious places. Proper safety equipment is essential.
Bridge Inspection
Inspection involves physical strength and intense concentration.
Bridge Inspection
Free-climbing requires safety lanyards and safety lines to maintain a 100 percent tied-off condition.

What happens once you complete the inspection?

Mike: After we have inspected each component of the bridge—taking photos and taking notes—we make recommendations for member replacements or repair of any deficiencies that we detect and submit a bridge inspection report into the system. Our report will include a narrative with supporting photos or sketches summarizing our inspection findings. We also update our client’s electronic database whether it’s PennDOT’s iForms / BMS2 record, or the Port Authority’s new Bridge Management System database. Based on these findings, we may have to re-analyze the bridge and update the load rating analysis to determine a safe load capacity. The load rating results determine if the bridge needs to be posted for a certain load limit. For instance, if the structure was Load Posted for ten tons prior to our inspection and our updated load rating analysis shows it could only safely carry eight tons, then we would take immediate action to coordinate with the bridge owner to re-post the bridge for the lower safe load capacity.

Brad: We also notify owners of any Critical Deficiencies we discover that may jeopardize public safety. If during an inspection we find a deficiency that warrants a code of zero—meaning Critical, action required within seven days, or one meaning High Priority, action required within six months—we would notify the owner of that condition immediately to mitigate the problem.

Mike Beresford, PE, CBSI, a 26-year GAI veteran, is currently leading the GAI team for a four-year, $11M agreement with the Port Authority of Allegheny County. The team will provide inspection and engineering services for 79 bridges that are owned and maintained by the Authority. The bridge type spans include simple spans, continuous spans, truss spans, through girders, prestressed concrete I-beams, and box beams, concrete encased steel beams, steel plate girders, and steel plate curved girders. 

GAI currently has four ongoing bridge inspection agreements:

To learn more about GAI’s Bridge Inspection and Design services, contact GAI Transportation Technical Manager Mike Beresford, PE, CBSI at 412.399.5326 and Senior Project Engineer Brad Kughn, PE, CBSI at 412.399.5350.

Michael Beresford, PE, CBSI
Brad Kughn, PE, CBSI

Read all the articles in this series and learn more about GAI’s bridge inspection services:

Bridge Inspection, Part Two: Working Safely to Ensure Public Safety

Bridge Inspection, Part Three: Coordinating River, Rail, and Road

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