As I scanned the Table of Contents for this October 2019 issue of Informed Infrastructure, I noticed the article title “Brick Sewer Rehabilitation in Nation’s Capital.” My first thought was that it didn’t read “Brick Sewer Replacement.” I’m sure that cost was a major (and perhaps only) factor in the decision to rehabilitate rather than replace.

But I also thought that we’ve approached the time when cost should only be one of many factors in such decisions. As we continue to engineer our way into the future, we need to be proactive and innovative in making our infrastructure last longer while using less resources.

Highway RAP

I remember driving along a highway and passing huge piles of broken-up concrete and ground-up bituminous material. One of my grandsons asked what those were, and I told him those piles were once a highway; they ground off the blacktop, broke up the concrete and hauled it to this yard. He then asked if anyone was going to use that stuff again, and here’s where it got boring for the young guy. I could have simply said “yes,” but I went on to explain how all that material was going to be reused in other projects as riprap or subbase or something else. He then asked if I could change the station, and I wasn’t sure if he meant the radio or my lecture.

That was my attempt to explain how engineers—especially engineers working with infrastructure—are recycling materials wherever possible. Many of us know the term Reclaimed Asphalt Pavement (RAP), and it’s part of the Federal Highway Administration (FHWA) policy to promote the use of RAP in highway construction and rehabilitation. In addition, the structural steel industry estimates that structural steel produced in the United States contains more than 90 percent recycled steel scrap. In fact, the term now being used is “multi-cycled,” because steel scrap can be used over and over again. These practices all contribute to reducing waste and preserving our natural resources.

Environmental Changes

Our environment is becoming more sensitive to the effects of our consumption of natural resources. Scientists are noting various changes in weather, water and air quality as well as limited fuel sources, all due to human factors. It’s no longer something you believe in or not.

Our infrastructure will not last forever. Engineers have been planning and designing with these issues in mind, but we need to be even more focused, innovative and intentional in finding methods to rehabilitate our existing infrastructure. Engineers can provide designs with the intent to allow for the easy rehabilitation or reuse of materials in the future.

I’m reminded of a time when I was discussing the fact that SUVs, while obtaining better mileage than they used to, still use more fuel than smaller vehicles; the other person noted than he could afford to pay for the fuel. Although it may be true for that individual, we’re rapidly approaching the time when society can’t afford to use that additional fuel. This is similar to addressing our infrastructure situation. Will we be able to afford to just replace, or do we need to find more ways to reuse and multi-cycle?

The FHWA policy on RAP states that three requirements must be met: RAP must be cost effective, environmentally responsible and perform well. I think we should change the order to make environmentally responsible first.

Will We Last?

A couple years ago, I wrote a column about some old bridges and other civil engineering projects that have lasted several hundred years. I then asked if any of the projects we’re a part of today will last that long. Will any of our distant ancestors look at one of our projects a few hundred years from now and be able to say they’re related to the designer or builder? If we can produce projects with multi-cycled materials, at least some aspects of those projects will last well into the future while prolonging the health of our environment.