Transportation Impacts & Adaptation

Climate Impacts on Alaska

In the United States, transportation systems are designed to withstand local weather and climate. Transportation engineers typically refer to historical records of climate, especially extreme weather events, when designing transportation systems. For example, bridges are often designed to withstand storms that have a probability of occurring only once or twice every 100 years. ^[1] However, due to climate change, historical climate is no longer a reliable predictor of future impacts.

Climate change is projected to increase the frequency and intensity of extreme weather events. Specifically, heat waves will likely be more severe, sea level rise could amplify storm surges in coastal areas, and storms will likely be more intense. ^[2] These changes could increase the risk of delays, disruptions, damage, and failure across our land-based, air, and marine transportation systems. Most transportation infrastructure being built now is expected to last for 50 years or longer. ^[1] Therefore, it is important to understand how future climate might affect these investments in the coming decades.

Top of page

Impacts on Land-Based Transportation

Climate changes will likely impact roadways, ice roads, vehicles, and railways.

Impacts on Roadways

Higher temperatures can cause pavement to soften and expand. This can create rutting and potholes, particularly in high-traffic areas and can place stress on bridge joints. Heat waves can also limit construction activities, particularly in areas with high humidity. With these changes, it could become more costly to build and maintain roads and highways. On the other hand, certain areas may experience cost savings and improved mobility from reduced snowfall and less-frequent winter storms since warmer winters may lead to reductions in snow and ice removal, as well as salting requirements. ^{[1] [2]}

Climate change is projected to concentrate rainfall into more intense storms. Heavy rains may result in flooding, which could disrupt traffic, delay construction activities, and weaken or wash out the soil and culverts that support roads, tunnels, and bridges. ^{[1] [2]}

Roadway damaged by Hurricane Katrina in 2005. Source: NASA (2005)

Exposure to flooding and extreme snow events also shortens the life expectancy of highways and roads. The stress of water and snow may cause damage, requiring more frequent maintenance, repairs, and rebuilding. Road infrastructure in coastal areas is particularly sensitive to more frequent and permanent flooding from sea level rise and storm surges. Approximately 60,000 miles of coastal roads in the United States are already exposed to flooding from coastal storms and high waves. Furthermore, major highways in coastal areas serve as critical evacuation routes. Evacuation routes must be protected from flooding and damage so they may be used for emergencies. ^{[2] [3]} In some locations, warmer temperatures are projected to cause more winter precipitation to fall as rain instead of snow. Winter flooding could occur more frequently, if the frozen ground cannot absorb precipitation. Landslides and wash-outs could also occur more frequently, as saturated soils are exposed to more rainwater. Drought in areas such as the Southwest could increase the likelihood of wildfires that reduce visibility and threaten roads and infrastructure. ^{[1] [2]}

View enlarged image

In the Gulf Coast, 2,400 miles of major roadway could be permanently flooded by sea level rise in the next 50 to 100 years. This map shows roadways at risk under relative sea level rise of about four feet—within the range of end-of-century projections for this region (under medium- and high-emissions scenarios). In total, 24% of interstate highway miles and 28% of secondary road miles in the Gulf Coast region are at elevations below 4 feet. Source: USGCRP (2009)

Impacts on Ice Roads

Freezing temperatures are required for ice roads in Alaska. These are frozen routes used to connect northern communities, as well as the oil, gas, and mining industries. The tundra beneath these frozen roads is fragile, so transportation is limited to periods when the road is frozen. Warming temperatures would reduce the number of days ice roads are open, limiting transportation access to these areas. ^[2] To learn more about the impacts of climate change on transportation infrastructure in Alaska, please visit the Alaska Impacts & Adaptation page.

Impacts on Vehicles

As temperatures increase, many types of vehicles can overheat, and tires will deteriorate more quickly. But milder winters, reductions in the number of cold days, delays in winter freezing, and earlier spring thaws may reduce cold-weather damage to vehicles. ^[1]

Impacts on Railways

Extreme heat can cause rails to buckle. Source: Volpe National Transportation Systems Center

High temperatures cause rail tracks to expand and buckle. More frequent and severe heat waves may require track repairs or speed restrictions to avoid derailments. ^[1] Heavy precipitation could also lead to delays and disruption. For example, the June 2008 Midwest floods closed major east-west rail lines for several days. Tropical storms and hurricanes can also leave debris on railways, disrupting rail travel and freight transport. ^{[1] [2]} Like roadways, coastal railways and subways are subject to inundation from sea level rise and storm surges. This is particularly true in underground pathways and tunnels, which are often already below sea level. Increased flooding from heavy precipitation and storm surges could disrupt rail travel as well as freight operations. Damages from flooding may require rail lines and subway infrastructure to be rebuilt or raised in future expansion projects. ^{[1] [2]}

Top of page

Impacts on Air Transportation

Climate changes may impact airplanes, airports, and airstrips, affecting air travel and infrastructure.

Impacts on Air Travel

Periods of extreme heat may cause airplanes to face cargo restrictions, flight delays, and cancellations. However, warmer weather in winter will reduce the need for airplane de-icing. ^[2]

In the winter and spring, increased rains and flooding may also disrupt air travel. Storms can force entire airports to close, as occurred along the Gulf Coast during Hurricane Katrina. ^{[1] [2]} Climate change may increase the frequency of these events and the number of airports that are affected.

Impacts on Air Transportation Infrastructure

In addition to causing closures or delays, flooding may damage facilities, including airstrips. Some of the busiest airports in the United States are located in low-lying coastal areas, making them particularly vulnerable to inundation. For example, in the tri-state area of New York, New Jersey, and Connecticut, many critical transportation infrastructure facilities (including Newark and LaGuardia airports) lie within the range of current and projected 50-year coastal storm surges. ^{[1] [2]}

Many airstrips in Alaska are built on permafrost. Warmer temperatures would thaw permafrost and cause soils to settle, potentially damaging the foundation and structure of key infrastructure. Runways and airports may require rebuilding, relocation, or increased maintenance. ^{[1] [2]}

Top of page

Impacts on Marine Transportation

Climate changes will likely affect marine transportation infrastructure and logistics in many ways, both positive and negative.

Impacts on Ships and Sea Lanes

Ships are sensitive to many factors, including the depth of a channel and the extent of sea ice. Increasing temperatures could reduce the amount of sea ice in many important shipping lanes, extending the shipping season. Warmer winters will likely lead to less snow and ice accumulation on vessels, decks, and rigging in marine transportation. In the Arctic, warmer temperatures could also open up the possibility of a Northwest Passage, which could reduce shipping times and distances. However, these new passages may also provide a pathway for invasive species transport and survival. ^{[1] [2]}

Shipping lanes experiencing sea level rise will be able to accommodate larger ships, reducing shipping costs. However, higher sea levels will mean lower clearance under waterway bridges. In inland waterways where water levels are expected to decline, as in the Great Lakes, ships could face weight restrictions, as channels become too shallow. ^{[1] [2]}

Changes in precipitation can affect shipping in many ways. Flooding could close shipping channels, and increased runoff from extreme precipitation events could cause silt and debris to build up, leading to shallower channels. Changes in precipitation patterns could also affect the rate at which sediments accumulate, which may also make existing channels shallower and less accessible. In areas experiencing increasing drought, water levels could periodically decrease, limiting inland shipping on rivers. More severe storms could increase disruptions in marine travel and shipping. ^{[1] [2]}

Impacts on Ports and Infrastructure

Hurricane Katrina damaged boats in Gulf Coast ports. Source: NOAA

Like other coastal infrastructure, harbor facilities, including docks and bridges, may have to be raised to accommodate higher tides and storm surges, as sea levels rise.

For example, in the Gulf Coast, which is home to seven of the 10 largest ports in the United States, the combination of relative sea level rise and more intense hurricanes and tropical storms could lead to significant disruptions and damage. ^{[1] [2]}

To learn more about adaptation measures in transportation, please see the Transportation Adaptation section.

Top of page

References

1. NRC (2008). The Potential Impacts of Climate Change on U.S. Transportation . Transportation Research Board Special Report 290. National Research Council (NRC).

2. USGCRP (2009). Global Climate Change Impacts in the United States . Karl, T.R., J.M. Melillo, and T.C. Peterson (eds.). United States Global Change Research Program. Cambridge University Press, New York, NY, USA.

3. FHWA (2008). Highways in the Coastal Environment (2nd edition). Hydraulic Engineering Circular 25, NHI-07-096. Federal Highway Administration (FHWA).

Top of Page

Adaptation Examples in Transportation

Sea level rise, more intense storms, and thawing permafrost are some of the impacts of climate change that are likely to affect transportation systems. To learn more about how climate change can impact transportation systems, visit the Transportation Impacts section.

Federal, state, and local agencies are taking steps to protect transportation systems from climate change impacts. Adaptation measures across the country are shaped by local impacts. Specific adaptation approaches include:

• Raising the level of critical infrastructure
• Changing construction and design standards of transportation infrastructure, such as bridges, levees, roads, railways, and airports
• Abandoning or rebuilding important infrastructure in less vulnerable areas

The following case studies, examples, and related links are illustrative of transportation adaptation actions and not intended to be comprehensive. Another example of adaptation related to transportation–the plans being made by the U.S. Navy to deal with the loss of sea ice in the Arctic–can be found in the Alaska Impacts & Adaptation page. 

Alaska’s Department of Transportation and Public Facilities addresses changes in permafrost

In Alaska, melting permafrost causes a road to collapse. Source: Federal Highway Administration (2010)

Alaska’s Department of Transportation and Public Facilities (ADOT & PF) manages a vast and complex network of transportation infrastructure, including over 14,000 miles of public roads, numerous bridges, rural airports, and harbors. This network is exposed to a variety of changes in climate that result in climate change impacts.

The Northern Region Maintenance and Operation agency of ADOT & PF spends approximately $10 million each year (PDF) to address damage to roads from the melting of frozen soil—also known as permafrost. The ADOT & PF is piloting the use of an alternative advanced cooling technology to absorb heat from the frozen soil and prevent thawing. The agency is also evaluating a method of permafrost protection that increases air circulation to maintain freezing temperatures below the road surface. This technology is currently being tested on the University of Alaska’s Fairbanks campus, through a partnership between the University and ADOT & PF. These efforts will help inform planning for the construction of new roads that can be protected against the adverse effects of thawing permafrost.

To learn more about adaptation measures in the region, visit the Alaska Impacts & Adaptation page.

Top of Page

California Department of Transportation Realigns Highway 1

The California Department of Transportation (Caltrans) is integrating climate considerations into its strategic planning. In San Luis Obispo County, Caltrans is moving part of Highway 1 inland due to current and projected coastal erosion and sea level rise. Caltrans expects this realignment to protect the iconic road for the next 100 years. In addition, the realignment is designed to minimize impacts to coastal resources by taking into account existing land use and conservation agreements.

View enlarged image

Caltrans proposed the route and viewpoints with purple arrows to replace the existing portion of Highway 1 that is closer to the coast. Source: California Department of Transportation (2008)

For more information about adaptation efforts in California, visit the Southwest Impacts & Adaptation page. To learn more about coastal adaptation, visit the Coastal Impacts & Adaptation page.

Top of Page

Piscataqua Regional Estuary Program in New Hampshire pinpoints sensitive roads and culverts

The Piscataqua Regional Estuary Partnership, supported by the EPA’s Climate Ready Estuaries program, used various evaluation methods to analyze and pinpoint the roads and culverts affected by changes in rainfall and extreme storm events. The project also estimated the costs of replacing and strengthening existing infrastructure, which can help decision-makers make an economic case for pursuing adaptation.

Top of Page

Federal Highway Administration assesses the vulnerability of transportation networks

The Federal Highway Administration (FHWA) developed a conceptual model for assessing the vulnerability of transportation systems to climate change. FHWA is working with five teams of transportation planners that are testing the model. These teams include the Metropolitan Transportation Commission in San Francisco, California; the New Jersey Department of Transportation (DOT)/North Jersey Transportation Planning Authority; Virginia DOT; Washington State DOT; and the Oahu Metropolitan Planning Organization in Hawaii. Lessons learned from these pilot projects will inform future efforts to develop guidance for other transportation agencies addressing impacts of climate change.

FHWA is also studying climate change impacts on transportation networks in the Central Gulf Coast region and evaluating adaptation options. The study is focused on:

• Understanding climate change effects on transportation infrastructure
• Identifying vulnerable transportation infrastructure in Mobile, Alabama
• Conducting detailed engineering and risk studies to identify options for strengthening critical transportation infrastructure
• Developing adaptation tools and methods that can be applied to other locations

To learn more about climate adaptation in the Gulf Coast, visit the Southeast Impacts & Adaptation page.

Top of Page