roadway miles, LCCA and LCA concepts get more complicated. A single asset can no longer be considered without considering its impact on the overall network. Transportation agencies have more needs than funds allow. Overspending on one project during initial construction can have a ripple effect on new and maintenance projects. Agencies must look at a balance of conditions over years or decades, but the funding is generally in 5- to 7-year intervals. Even then, funding levels can swing wildly within 18 to 24 months. LCA has the same challenges as LCCA when it comes to use in decision-making. The materials and processes used today will be different in 10 years. Consider the impact of warm-mix technology on plant fuel use. How about the development of high-performance asphalt binders? Ten or twenty years ago, these advancements were conceptual and in the early deployment stages. How could they be considered in an LCA when not implemented and understood? And despite their wider use today, they are in many ways still data gaps in our LCAs. As more innovations are created to drive down greenhouse gas emissions and improve material/pavement performance, an LCA decision today may not provide the lowest carbon solution tomorrow. PAST PERFORMANCE AND INDICATOR OF FUTURE RETURNS So, what does an agency do? Should they ignore LCCA and LCA? Should an owner focus on what is known while recognizing the unknown circumstances and innovations that will impact the longterm performance of a pavement? Let us start with what we know. First, many pavements built during the interstate construction era are still in service. Most of Virginia’s asphalt pavements on the interstate system are still in service. Some sections have been removed and rebuilt, but the overwhelming majority have the same base asphalt produced in the 1960s and 1970s. These mixes were laid long before implementing many quality measures and metrics we use today. The concrete sections have been overlaid with asphalt or removed and replaced. We know how these pavements performed, but did the initial designers know? Today, we have more sophisticated pavement design software tools to predict performance. These tools account for material properties, environmental impacts, and truck loadings. Many of these tools rely on past performance to indicate future returns or performance. Arguably, this is the best information available for decision-making, and the output from these tools can be incorporated into an LCCA and LCA. Nevertheless, the unknown still exists and will impact a pavement design’s actual economic and environmental cost over the analysis life (i.e., cradle to grave). WHAT DO WE DO? “What do we do?” is a common question transportation agencies ask. Agencies are encouraged or even mandated to use LCCA and LCA outputs in pavement type decisions. As pointed out earlier, these decisions are not independent but vary dependent on funding and other network asset needs. Agencies cannot proceed with a very cheap or costly pavement choice, but pavement that meets △ continued from page 14 MORE THAN MEETS THE EYE: UNDERSTANDING LCCA AND LCA US 340 Bridge Replacement 16 FALL/WINTER 2024
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