Climate Change Will Have A Significant Impact On Transportation

Mar 11: A new report from the National Academy of Sciences (NAS), National Research Council (NRC) indicates that while every mode of transportation in the U.S. will be affected as the climate changes, potentially the greatest impact on transportation systems will be flooding of roads, railways, transit systems, and airport runways in coastal areas because of rising sea levels and surges brought on by more intense storms. The report says that although the impacts of climate change will vary by region, it is certain they will be widespread and costly in human and economic terms, and will require significant changes in the planning, design, construction, operation, and maintenance of transportation systems.

The U.S. transportation system was designed and built for local weather and climate conditions, predicated on historical temperature and precipitation data. The report finds that climate predictions used by transportation planners and engineers may no longer be reliable, however, in the face of new weather and climate extremes. Infrastructure pushed beyond the range for which it was designed can become stressed and fail, as seen with loss of the U.S. 90 Bridge in New Orleans after Hurricane Katrina.

Henry Schwartz Jr., past president and chairman of Sverdrup/Jacobs Civil Inc., and chair of the committee that wrote the report said, "The time has come for transportation professionals to acknowledge and confront the challenges posed by climate change, and to incorporate the most current scientific knowledge into the planning of transportation systems. It is now possible to project climate changes for large subcontinental regions, such as the Eastern United States, a scale better suited for considering regional and local transportation infrastructure."

The committee identified five climate changes of particular importance to U.S. transportation; 1) increases in very hot days and heat waves; 2) increases in Arctic temperatures; 3) rising sea levels; 4) increases in intense precipitation events; and 5) increases in hurricane intensity. In addition to climate changes, there are a number of contributing factors that will likely lead to vulnerabilities in coastal-area transportation systems. Population is projected to grow in coastal areas, which will boost demand for transportation infrastructure and increase the number of people and businesses potentially in harm's way; erosion and loss of wetlands have removed crucial buffer zones that once protected infrastructure; and an estimated 60,000 miles of coastal highways are already exposed to periodic storm flooding.

Schwartz said, "Rising temperatures may trigger weather extremes and surprises, such as more rapid melting of the Arctic sea ice than projected. The highways that currently serve as evacuation routes and endure periodic flooding could be compromised with strong hurricanes and more intense precipitation, making some of these routes impassable." Transportation providers will need to focus on evacuation planning and work more closely with weather forecasters and emergency planners.

Infrastructure vulnerabilities will extend beyond coastal areas as the climate continues to change. In the Midwest, for instance, increased intense precipitation could augment the severity of flooding, as occurred in 1993 when farmland, towns, and transportation routes were severely damaged from flooding along 500 miles of the Mississippi and Missouri river systems. On the other hand, drier conditions are likely to prevail in the watersheds supplying the St. Lawrence Seaway and the Great Lakes as well as the Upper Midwest river system. Lower water levels would reduce vessel shipping capacity, seriously impairing freight movements in the region, such as occurred during the drought of 1988, which stranded barge traffic on the Mississippi River. And in California, heat waves may increase wildfires that can destroy transportation infrastructure.

Not all climate changes will be negative, however. Marine transportation could benefit from more open seas in the Arctic, creating new and shorter shipping routes and reducing transport time and costs. In cold regions, rising temperatures could reduce the costs of snow and ice control and would make travel conditions safer for passenger vehicles and freight.

Preparing for projected climate changes will be costly. Transportation decision makers continually make short- and long-term investment decisions that affect how the infrastructure will respond to climate change. Response measures range from rehabilitating and retrofitting infrastructure to making major additions to constructing entirely new infrastructure. The committee noted the need for "a more strategic, risk-based approach to investment decisions that trades off the costs of making the infrastructure more robust against the economic costs of failure." In the future, climate changes in some areas may necessitate permanent alterations. For example, roads, rail lines, and airport runways in low-lying coastal areas may become casualties of sea-level rise, requiring relocations or expensive protective measures, such as sea walls and levees.

The report calls for the federal government to have a strong role in implementing many of its recommendations that require broad-based action or regulation, such as the creation of a clearinghouse for information on transportation and climate change; the establishment of a research program to re-evaluate existing design standards and develop new standards for addressing climate change; creation of an interagency working group on adaptation; changes in federal regulations regarding long-range planning guidelines and infrastructure rehabilitation requirements; and re-evaluation of the National Flood Insurance Program and updating flood insurance rate maps with climate change in mind.

The NRC report follows another major report on transportation issues -- the recent Transportation for Tomorrow report of the National Surface Transportation Policy and Revenue Study Commission released on January 15, 2008. That report was prepared by the specially convened Commission, under Section 1909 of the Safe Accountable, Flexible and Efficient Transportation Equity Act -- A Legacy for Users (SAFETEA-LU). The Report includes detailed recommendations for creating and sustaining a pre-eminent surface transportation system in the United States [See WIMS 1/31/08]. GAO testified at a hearing on the report saying the nation has reached a critical juncture with its current surface transportation policies and programs. Demand has outpaced the capacity of the system, resulting in increased congestion. In addition, without significant changes in funding mechanisms, revenue sources, or planned spending, the Highway Trust Fund -- the major source of federal highway and transit funding -- is projected to incur significant deficits in the years ahead [See WIMS 2/6/08].

The NRC report was a collaborative effort between the Transportation Research Board and the Division on Earth and Life Studies of NRC. The sponsors of the report are the Transportation Research Board, National Cooperative Highway Research Program, U.S. Department of Transportation, Transit Cooperative Research Program, U.S. EPA, and the U.S. Army Corps of Engineers.

Access a release (click here). Access a report summary (click here). Access the complete 234-page report (click here). Access various Commissioned Papers for the NRC report (click here). [*Transport, *Climate]