Quantifying Risk Shows Value of Replacing Highway
Climate stressors and impacts
Rising seas and sinking land in Louisiana threaten transportation corridors from the Gulf of Mexico to the rest of the nation. Some roads in the state are already impassable during high tides, and the problem is expected to worsen over the coming decades. With many miles of roadway vulnerable to inundation across the state, Louisiana’s Department of Transportation and Development has to set priorities for which roads should be rebuilt. Considering the potential consequences of each road becoming unusable—the risk associated with its loss—is one method for deciding where to spend limited resources.
Port for oil
Port Fourchon is a busy seaport on the southern coast of Louisiana; it services almost 90 percent of the deep-water drilling rigs and oil production operations in the Gulf of Mexico. More than 15 percent of the United States’ domestic oil supply already comes through Port Fourchon, and industry forecasts indicate the majority of future drilling in the region will be in the Port Fourchon service area. In addition to this critical energy transportation purpose, the port also serves as a hub for commercial and recreational fishing.
Building a highway to build resilience
At the turn of the century, the old Louisiana Highway 1 (LA-1) connected Port Fourchon to the rest of the nation. However, frequent inundation made it clear the road wouldn't last for long. Would the cost of rebuilding this particular road be worth the investment it would take? In 2006, an economic impact study estimated that a three-week loss in services from Port Fourchon would lead to $10 billion in lost sales for United States' firms. The loss of LA-1 would also threaten our nation’s energy security. Based on the potential consequences the state and nation could suffer from losing the road, it made good sense to invest in making LA-1 more resilient.
Using satellite data to document observed rates of land subsidence and sea level rise, and consulting model data to project trends into the future, highway engineers designed a 17-mile stretch of new roadway to replace the old LA-1. Beginning in 2008, Louisiana’s Department of Transportation and Development built the elevated roadway resting on strong, 17-foot-tall pillars to make it more resilient to flooding, tropical storms, and storm surge. Even as waves lap along the edges of the old road, engineers expect the new structure will last for at least 75 years, serving as one of the nation’s main arteries for oil and gas.
- Scott, L.C., and Coauthors, 2008: The Economic Impacts of Port Fourchon on the National and Houma MSA Economies. Greater Lafourche Port Commission, 28 pp.