ABSTRACT:The states in the Pacific Northwest and Alaska region share interconnected transportation networks for people, goods, and services that support the regional economy, mobility, and human safety. Regional weather has and will continue to affect the physical condition and serviceability of these networks, yet the nature of climate changes and their potential impacts on the regional transportation system and its use are very poorly understood. The world's leading climate scientists, such as the Intergovernmental Panel for Climate Change, have reached consensus that global climate changes are being observed and will continue into the future, particularly increasing temperatures. Given this fact, the widely diverse topography, climate regimes, and localized variability of impacts within the region complicate efforts to understand and plan for adapting to the potential impacts of climate change on the regional transportation system. The rising costs of building and maintaining reliable transportation infrastructure place tremendous pressure on transportation planners, engineers, researchers and policy makers to deliver resilient transportation systems and maximize return on investment. As such, there is an urgent need to synthesize information to characterize the regional impacts of climate change to support the development of economical and resilient adaptation strategies.Climate impacts are posing continued challenges for state departments of transportation (DOT). Changing weather patterns and their associated physical, financial, and social impacts are affecting or will affect the way transportation professionals finance, plan, design construct, operate, and maintain multimodal transportation infrastructure. Many state transportation agency procedures and practices were developed without full consideration of the likely impacts of climate change. For example, more frequent, high intensity precipitation events and associated floods may lead to expensive and unpredictable catastrophic failures of roads and bridges designed with outdated hydrologic data. DOTs could experience hundreds of millions of dollars in infrastructure damage that potentially could be avoided with more robust data collection, planning, and design tools/methods for managing risks. Likewise, climate-related socioeconomic changes may also be occurring, but transportation planners are currently ill-equipped to analyze them and may be delivering transportation projects that do not address future needs. Decisions made today on the planning and design of the regional transportation system will affect resiliency of the system as region tries to adapt to climate change. Making well informed and thoughtful decisions now will help avoid costly modifications and disruptions to operations in the future.This report is built on several significant reports and projects that have been recently published. In 2008, the Transportation Research Board released the Special Report 290: Potential Impacts of Climate Change on U.S. Transportation, which primarily ...