Climate change impacts will increase the total costs to the nation’s transportation systems and their users, but these impacts can be reduced through rerouting, mode change, and a wide range of adaptive actions.

This finding is from chapter 5 of Climate Change Impacts in the United States: The Third National Climate Assessment.

Process for developing key messages: In developing key messages, the chapter author team engaged, via teleconference, in multiple technical discussions from January through May 2012 as they reviewed numerous peer reviewed publications. Technical input reports (21) on a wide range of topics were also received and reviewed as part of the Federal Register Notice solicitation for public input. The author team’s review included a foundational Technical Input Report for the National Climate Assessment, “Climate Impacts and U.S. Transportation.”6b4d3283-49dc-4b8d-830b-aa554e37279f Other published literature and professional judgment were also considered as the chapter key messages were developed. The chapter author team met in St. Louis, MO, in April 2012 for expert deliberation and finalization of key messages.

Description of evidence base: The economic cost of climate change to the transportation sector has been little studied. However, there is substantial evidence that costs will be significant. A recent study of climate change in New York indicated that a storm surge severe enough to flood Manhattan tunnels might cost as much as $100 billion.78fbf40c-2639-480a-8410-5be748750f2b The actual experience of Hurricane Sandy, where multiple tunnels were flooded, attests to the scale of the costs and disruption that attend an event of this magnitude (See also Ch. 11: Urban; Box on Hurricane Sandy). A study of the risk to specific infrastructure elements in Alaska269e8640-18d1-4f61-aa0f-55eb3fbea2d2 estimated the net present value of the extra cost from climate change at $2 to $4 billion through 2030, and $4 to $8 billion through 2080. The indirect evidence for significant costs from climate change impacts begin with the consequences of recent hurricanes, particularly on the Eastern seaboard, where Hurricane Irene, a rather minor storm, produced unexpectedly heavy infrastructure damage from heavy rains.0ca902b2-504f-4bc2-b171-5bd184ae167d The economic cost of infrastructure damage is often greater than the cost of repairing or replacing infrastructure. In addition, a recent study of on-road congestion estimates the annual cost of highway congestion at about $100 billion,5b9e690a-2955-4ff9-8e1a-679e51647415 and the Federal Highway Administration estimates that weather accounts for about 15% of total delay.ea212f08-1bee-4e57-b7b3-bb6f39f63154 Similarly, a recent study of aviation congestion indicates that the annual cost of airline delay is about $33 billion86603a44-48ce-49a6-acc6-17047a56ad97 and that weather accounts for more than a third of airline delays. There is a strong circumstantial case to be made that increased frequency of extreme events (as defined by climate scientists) will produce increased traffic and aviation delays. Given the scale of current costs, even small changes in delay can have substantial economic costs. There is little published material on transportation adaptation costs and benefits in the literature, in part because “adaptation” is an abstraction (see Ch. 28: Adaptation). Climate change is statistical weather, and manifests itself as a change in the frequency of events that would still occur (but with lower frequency) in the absence of climate change. Transportation agencies decide to protect (or not) specific pieces of infrastructure based on a range of considerations, including age and condition, extent of current and future usage, and cost of protection, as well as changing weather patterns. The authors, however, are aware, that transportation systems have always been required to adapt to changing conditions, and that, in general, it is almost always far less expensive to protect useful infrastructure than to wait for it to collapse. This professional experience, based on examination of multitudes of individual engineering studies, is the basis for the conclusion in this report (for example, Caltrans Climate Change Workshop 2011, CCSP 2008, and Meyer 20088dbd70c4-cd8c-4dce-b27c-bfb412901e58 8aa9da42-0886-4d5a-8206-758e5e422fb0 ff57bdc7-a07b-4bb2-b320-a0755305605a). There are numerous examples of actions taken by state and local governments to enhance resilience and reduce climate impact costs on transportation, including land-use planning to discourage development in vulnerable areas, establishment of design guidelines to reduce vulnerability to sea level rise, use of effective stormwater management techniques, and coordinated emergency response systems.351fbf4f-480e-450e-9cc3-9cecd429f564 ff57bdc7-a07b-4bb2-b320-a0755305605a

New information and remaining uncertainties: There is relatively little information on the costs of climate change in the transportation sector, and less on the benefits of adaptation. Much of the available research is focused on the costs of replacing assets that are affected by extreme weather events, with far less effort devoted to both longer-term impacts of climate change on transportation systems (such as inundation of coastal roads due to sea level rise) and to the broader effects of disrupted facilities on network operations or on the community, for example, rerouting of traffic around bottlenecks or evacuation of sensitive populations from vulnerable areas. Calculating climate impact and adaptation costs and benefits is an exceptionally complex problem, particularly at high levels of aggregation, since both costs and benefits accrue based on a multitude of location-specific events. In addition, all of the methodological issues that are confronted by any long-term forecasting exercise are present. The forecasting problem may be more manageable at the local and regional scales at which most transportation decisions are usually made.

Assessment of confidence based on evidence: The authors have high confidence that climate impacts will be costly to the transportation sector, but are far less confident in assessing the exact magnitude of costs, based on the available evidence and their experience. The authors also have high confidence, based upon their experience, that costs may be significantly reduced by adaptation action, though, as noted, the magnitude of such potential reductions on a national scale would be difficult to determine.

References :

• SAP 4.7. Impacts of Climate Change and Variability on Transportation Systems and Infrastructure: Gulf Coast Study (8dbd70c4)
• Traffic Congestion and Reliability: Trends and Advanced Strategies for Congestion Mitigation (ea212f08)
• webpage Tropical Storm Irene: By the Numbers (0ca902b2)
• Total Delay Impact Study: a Comprehensive Assessment of the Costs and Impacts of Flight Delay in the United States (86603a44)
• Developing coastal adaptation to climate change in the New York City infrastructure-shed: process, approach, tools, and strategies (78fbf40c)
• Estimating future costs for Alaska public infrastructure at risk from climate change (269e8640)
• Design Standards for US Transportation Infrastructure: The Implications of Climate Change (8aa9da42)
• 2011 The Urban Mobility Report (5b9e690a)
• Guidance on Incorporating Sea-Level Rise: For Use in the Planning and Development of Project Initiation Documents (ff57bdc7)
• Potential Impacts of Climate Change on U.S. Transportation. Special Report 290 (351fbf4f)
• Climate Impacts and U.S. Transportation: Technical Input Report for the National Climate Assessment. DOT OST/P-33 (6b4d3283)