TRANSPORTATION INFRASTRUCTURE
Climate change is projected to have far-reaching impacts on transportation networks and infrastructure. Rising sea levels, more extreme weather events, changes in precipitation, higher temperatures, and permafrost thawing are among the climate changes that will challenge the country's transportation systems.
All regions and modes of transportation will be affected, but coastal areas are particularly vulnerable. Nearly half the U.S. population lives within fifty miles of the coast, and a large portion of our transportation infrastructure is located in coastal zones. The risk is particularly acute for Gulf Coast communities that sit on subsiding land -- where local land elevation is sinking relative to sea level.
Five types of climate impacts are likely to be the most significant for U.S. transportation systems.
- Sea-level rise
- Rising sea levels can innundate coastal transportation infrastructures. Many roads and rail lines were built at water's edge to take advantage of more level routes or available rights-of-way. Airports, too, were often built in wetlands and other 'undesirable' coastal areas.
- The networked nature of the transportation system means that even elevated infrastructure can be affected. Highways can be out of reach, for example, if their approach ramps are under water.
- Low-lying evacuation routes may not be available.
- Ports and off-shore pipelines are vulnerable.
- There may be less clearance under low bridges.
- Increased storm intensity
- Storm surges that accompany coastal storms can damage or destroy roads, bridges, culverts, piers, ports, and subway and rail lines. Hurricane Katrina storm surges, for example, destroyed billions of dollars in infrastructure, including coastal roads, rail lines, and major highway bridges.
- Underground transit facilities are particularly vulnerable to flooding where ventilation openings and other access points are not sufficiently elevated. According to the Federal Transit Authority, "the most disruptive near-term impact [of climate change] is likely to be intense rainfall that floods subway tunnels and low-lying facilities."
- High storm winds can damage overhead cables and disrupt roadway operations with downed trees and debris.
- On the other hand, decreases in winter snowstorms (with more winter precipitation falling as rain due to higher temperatures) could reduce winter maintenance needs and costs as well as the use of environmentally damaging road maintenance substances.
- Changes in precipitation
- Extreme rainfall can overwhelm drainage systems, causing localized flooding. Many culverts are too small to handle the increased volume and intensity of more extreme rain events.
- Increased precipitation and runoff can cause subsidence, landslides, and structural instability.
- Severe storms create delays and disruptions to almost all types of transportation.
- Changes in precipitation together with increasing temperatures could have a significant impact on inland waterways. The Great Lakes are projected to experience declining water levels, which will reduce shipping capacity. On the Mississippi River, both drought and flood conditions can stop barge traffic.
- Decreasing rates of precipitation can lead to drying and shrinking soils, which can affect the base under pavements and other structures. Roadways, pipelines, runways, and rail lines may sink or fall in, and piers may be far from the water.
- Higher temperatures
- Higher temperatures can cause railroad tracks to buckle, leading to rail system downtime and derailments.
- Extreme heat can cause pavement to soften and expand, which can cause rutting and potholes, particularly in high traffic areas.
- Warmer air is less dense, and lower air density makes it harder for planes to take off, which can lead to air travel delays and weight reduction on cargo flights at airports where runways are not long enough to compensate.
- Higher temperatures, decreases in ice cover, and increases in evaporation are expected to lower water levels in the Great Lakes and the Saint Lawrence Seaway, leading to reductions in freighters' cargo-carrying capacity. On the other hand, reduced ice cover on inland waterways could lengthen the shipping season.
- Shorter winters will lengthen the construction season in some places, but extreme heat will limit construction and maintenance activities.
- Warmer winters could decrease the need for winter road maintenance.
- Arctic permafrost thawing and sea ice melt
- A large portion of the Arctic region's transportation infrastructure is built on permafrost foundations, which are thawing as winters become shorter and temperatures rise. This is already damaging roads, airports, and railways in the region.
- Shorter winters are reducing the "ice road" trucking season, those months when a network of "ice roads" is used to transport heavy loads to otherwise isolated rural communities.
- As sea ice retreats, coastlines are losing the protection previously provided by the ice sheet, leaving villages and transportation systems vulnerable to erosion due to waves.
- The reduction in waterway ice cover will open the Arctic Northwest Passage, changing sea shipping routes and bringing major changes to the ecology of the region.
Adaptive solutions fall into four broad categories --
- Maintain and manage.
- Incorporate more intensive maintenance schedules into routine operations (e.g., more frequent clearing of drains and culverts).
- Strengthen and protect.
- Revise design standards (e.g., higher bridge heights, elevated roadways, bigger culverts).
- Develop adaptive materials (e.g., heat-resistant paving materials).
- Site new facilities outside of expanded flood plains.
- Employ green infrastructure solutions for stormwater management.
- Build or enhance protective systems (e.g., levees and dikes).
- Develop or enhance natural buffers (e.g., wetlands).
- Develop technology to provide advance warning of potential infrastructure failures due to the effects of weather and climate extremes.
- Enhance redundancy.
- Develop alternate routes and services to maintain continuity of travel.
- Abandon/relocate.
- Move critical infrastructure inland. Use flood-prone areas for parks.
WHAT LEAGUES CAN DO TO HELP THEIR COMMUNITIES MANAGE CLIMATE IMPACTS ON TRANSPORTATION SYSTEMS
Start by reviewing the general information about What Your League Can Do To Promote Climate Preparedness In Your Community.
Information gathering suggestions --
- Watch the 30-minute video Culvert Operations. The University of Maine Sustainability Solutions Initiative project team met with local towns in coastal Maine, thinking that the transportation-related climate adaptation issue would be storm surges and/or sea level rise. They learned instead that the issue is culverts. Some communities are finding out the hard way that their culverts are no longer big enough to handle the volume of stormwater from increasingly heavy rain events. Culverts are critical to maintaining roadway integrity. Failed culverts can disrupt lives and commerce, threaten fragile ecosystems, and quickly overwhelm municipal budgets.
- Meet with local and/or state transportation officials to learn what steps are being taken to improve the resiliency of the transportation infrastructure in your area and to provide for alternatives.
Examples of programs and initiatives to improve resiliency to climate impacts on transportation systems --
- Sponsor a workshop on green infrastructure that home- and business-owners can implement.
- Promote policies to expand the use of green infrastructure (e.g., ordinance requiring permeable paving for parking lots).
- Work with municipal leaders to improve the resiliency of your community's transportation infrastructure.
- Promote a pipe and culvert vulnerability assessment and/or an expanded maintenance plan for more frequent culvert clearing.
- Work with municipal leaders to ensure that groups who disproportionately depend on public transportation -- persons with disabilities, older adults, low-income individuals -- have transportation options in the event of an emergency.
- Work with municipal leaders to develop emergency evacuation services that can be deployed in the event of a serious disruption.
RESOURCES
- The Third U.S. Climate Assessment includes a chapter that addresses the impact of climate change on U.S. transportation systems. (May 2014, U.S. Global Change Research Program)
- Transportation Adaptation to Climate Change (December 2009, Bipartisan Policy Center) identifies policy options available to ensure a robust transportation system in the face of a changing climate.
- Ensuring Transportation Infrastructure and System Resilience, U.S. Department of Transportation Climate Adaptation Plan (May 2013) discusses the transportation sector's vulnerabilities to climate change and identifies actions DOT will take to improve the sector's ability to build resistence to the threats posed by climate change.
- Flooded Bus Barns and Buckled Rails: Public Transportation and Climate Change Adaptation (August 2011, Federal Transit Administration) examines anticipated climate impacts on U.S. transit and current climate adaptation efforts by domestic and foreign transit agencies.
- EPA's webpage on Climate Impacts on Transportation discusses impacts on land-based, air, and marine transportation. EPA's list of Climate Adaptation Resources and Guidance includes some resources related to transportation.
Last updated: 6/4/2014