Spring finally has arrived here in the Midwest (Chicago, to be specific): flowers are blooming, trees are budding out, birds are singing, and baseball is in full swing. But April 2018 was the fourth-coldest April on record; the Chicago Cubs home opening game on April 6th was postponed due to snow. Tulips are just now blooming, and the trees are a month behind in their growth.

Another event that starts in the spring in our area is construction season: the time of year when a little more patience is required when traveling along the highways. Lanes are closed for resurfacing or bridge repairs. Warning signs pop up, noting that mowing crews are working ahead. So you slow down or stop, crank up the oldies station, and sing along with Led Zeppelin; or check in with Waze and find another route.

Bridge Inspections

I read with great interest a “sneak peak” of Rajika Jayatilake’s column “A Bridge Too Far (Gone)” (page 20). She writes: “federal and state guidelines for manual inspection are about 50 years old,” and I know that’s true. Years ago, when I worked for the Indiana Department of Transportation, spring also was the time of year to begin the “bridge inspection sprint.”

Each of the regional districts would send in to the central office its list of bridges they determined needed to be replaced or rehabilitated. We would divide up into teams of two and plot our weeklong trips through the districts, inspecting all the bridges on the list plus any others that we in the central office knew were in some state of disrepair. It was a welcome relief from spending the entire winter in the office.

While thinking about the bridge inspections, I immediately remembered the “Structure Inventory and Appraisal” (SI&A) form we used. My curiosity led me to INDOT’s website and the bridge inspection section. Sure enough, the SI&A still is in use, although the data now are transferred electronically. So I can personally attest to the validity of Jayatilake’s statement: at least for 47 years, we are inspecting bridges in much the same manner as we did back then.

Views from the Field

I remember very clearly my first project assignment, which included my first bridge inspection. The central office received a report that a bridge had been struck by a semi tractor-trailer. I’m fairly certain that the bridge was a through Pratt truss—there were still quite a few of those on the highway system back then.

When we arrived at the bridge site, I could see that the vehicle had hit the second sway frame hard enough to pull the vertical members inward. I climbed up the lattice work on the vertical and looked around for any damage to the members beyond the deformation. The following is a complete list of all the equipment I had for this inspection: one black and white Polaroid camera, one clipboard, and a hardhat. No, I didn’t have a vest; and no, I wasn’t tied off in any way. We didn’t even stop traffic, and I felt firsthand how much a bridge moves when traffic rolls across it.

But I was able to see very closely what damage had been done, and, from this, we could determine the method of repair. What I couldn’t see were any microscopic cracks in any of the other members that new technologies might be able to detect. But the senior engineer and I were confident that what I observed would provide enough information to repair the structure and restore it to full use.

Paving the Way for New Technologies

As I have said in this column before, new software and technologies enable engineers to perform much of their work more accurately and quickly. But we can never overlook the need for the engineer to be able to understand the theory and practice that lies behind all these new developments. Data can be correct, but analysis, interpretation and judgment still remain the important responsibility of the engineer. We must never lose sight of the fact that the public we serve relies on the engineer’s experience and knowledge.

There’s one concern that I have with Jayatilake’s column, but it’s just a personal reflection. She refers to “inspectors using methods that belong in a bygone era.” Having worked in that era, that ranks right up there with receiving a copy of bridge plans that I signed as a P.E. from my civil engineer son who is preparing to replace that bridge. At least my colleagues and I provided a baseline so new technologies have something to be compared.