U.S. GAO Climate Change report: Future Federal Adaptation Efforts Could Better Support Local Infrastructure Decision-Makers – Transportation Findings

The U.S. Government Accountability Office (GAO) issued a report that analyzed findings on the impacts of climate change on the nation’s infrastructure, including roads and bridges, and provided recommendations for Executive action to improve the resilience of the nation’s infrastructure. To develop the report, the GAO analyzed National Research Council (NRC) and the U.S. Global Change Research Program (USGCRP) climate change assessments and reports, conducted interviews with professional and agency stakeholders, and went on site visits to seven locations where adaptation measures have been integrated into infrastructure project planning. The report illustrates the GAO's findings on infrastructure vulnerabilities to climate change, efforts to incorporate climate change into infrastructure planning, factors that facilitate implementation of adaptive measures, and ongoing federal efforts to address local adaptation needs.

Three of the GAO’s seven site visits focused on transportation infrastructure: the Interstate-10 Twin Span Bridge in Louisiana, Louisiana State Highway 1, and Washington State Route 522. For each site visit, the report describes the projected short- and long-term climate impacts, the specific adaptive measures adopted, and how - and to what extent - climate change was integrated into the project planning process. Based on information obtained during these site visits, the GAO identified four key factors that enable local decision makers to integrate climate change into project planning.  These include: (1) having local circumstances that spurred action, such as a recent weather-related natural disaster or strong leadership, (2) learning how to use available information and deal with uncertainty, (3) having access to local assistance to translate climate information and help communicate risks to the public, and (4) considering climate impacts within existing planning processes and in the same context with other potential risks. The report discusses each of these factors using examples from information obtained during the site visits.

One of the GAO site visits focused on the process to elevate an 11-mile segment of Louisiana State Highway 1, which is increasingly vulnerable to storm surge given rising sea levels and local land subsidence. Bridge designers raised a segment of the highway by 22.5 feet to protect the road from 100-year flood events, and utilized additional measures to prevent dislodging of the road deck in the event of large storm surges. Subsequently, during Hurricane Isaac, the raised segment fared well while the unraised sections sustained damage.

The report also discusses a GAO site visit to study adaptive measures installed when the Interstate-10 Twin Span Bridge in Louisiana was rebuilt. To protect the bridge from storm surges caused by hurricanes, decision makers integrated several adaptive measures into the new design, such as: utilizing open railings to reduce wave forces, increasing elevation above peak wave heights, lengthening support deeper into the soil, and other measures to accommodate wave force and increase resilience to saltwater. The bridge also fared well during Hurricane Isaac in 2012. One of the factors that supported incorporation of climate change in the Twin Span Bridge project was learning how to use available data, specifically historical storm surge data that was used to develop scenarios for wave height and hurricane tracks.

The GAO also studied adaptive measures along Washington State Route 522 and its Snohomish River Bridge, which are likely to experience increased precipitation and flash flooding. Bridge engineers deepened the bridge footings to protect against the effects of erosion around the foundations (scour) that is likely to be caused by greater fluctuations in peak flows. The bridge was also elevated 10 feet above historic peak flows to accommodate the projected increases in precipitation and flash flooding. A factor that supported incorporation of climate change into project planning for State Route 522 and the Snohomish River Bridge was the local circumstances, specifically the existence of a 2007 Executive Order directing development of a climate change initiative.

The report also provided a general overview of climate change impacts on transportation infrastructure, specifically roads and bridges, using information from NRC and USGCRP assessments. Impacts such as warmer temperatures, changes in precipitation patterns, sea-level rise, and more frequent and intense storms and extreme weather events will affect transportation infrastructure in many ways. For example, more freeze-thaw conditions can create potholes on roads and bridges, necessitating load restrictions in order to minimize damage. Storm surge, combined with sea-level rise, is projected to have a wide range of negative impacts on roads and bridges, such as increasing inundation and flooding of coastal roads and low-lying infrastructure, erosion of road bases, and bridge “scour”  caused by erosion of riverbeds and the resulting exposure of bridge foundations. Landslides, slope failure, and flooding are also projected to increase as a greater proportion of winter and spring precipitation falls as rain instead of snow. In addition, increased precipitation is likely to cause more weather-related accidents, delays, and traffic disruptions, and evacuation routes are likely to flood more frequently.

The report also discussed how future federal efforts could better support local adaptation by continuing efforts to raise awareness of adaptation, improving access to and use of climate data and information, increasing access to local assistance, and considering climate change in existing planning processes. Based on its analysis of existing reports and information obtained during site visits and interviews, the GAO developed several recommendations for Executive Action to improve resilience of the nation’s infrastructure. These recommendations include:

  • Designation of a federal entity to work with agencies to identify and update the best available climate information and clarify sources of local assistance for incorporating this information into infrastructure planning;
  • Development of guidance by the Council on Environmental Quality for agencies to consider climate change effects in NEPA evaluations; and
  • Collaboration between the U.S. Department of Transportation, the Environmental Protection Agency, and professional associations to incorporate climate change information into design standards.

Since the release of this report, the federal government launched a Climate Data Initiative and an online Climate Resilience Toolkit, both designed to increase accessibility of climate-related data and information in order to support local data-driven planning and efforts to improve resilience.

 

This Adaptation Clearinghouse entry was prepared with support from the Federal Highway Administration. This entry was last updated on March 21, 2016.

 

 

Publication Date: May 14, 2013

Related Organizations:

  • U.S. Government Accountability Office (GAO)

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  • Case study
  • Policy analysis/recommendations
  • Progress report

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