[co-author: Dr. Mark Abkowitz]

If you are a company that relies on roads, rail, pipeline, air, or barge to move products, people, or supplies, or a transportation planner charged with the maintenance or smooth running of the transportation system, chances are that extreme weather has impacted you in the recent past. Indeed, extreme weather and climate change have been major contributors to transportation disruption and maintenance issues across the country. Transportation agencies must respond to more of these events, and more severe events, than ever before.

Recognizing these impacts, the federal government is doing more to address them, both by assisting in voluntary efforts at the state and local levels, and imposing mandatory requirements.

• In November 2013, President Obama issued Executive Order 13653, requiring all federal agencies to integrate considerations of climate change into their operations.
• In 2014, the Council on Environmental Quality issued draft guidance for agencies in incorporating climate change considerations into NEPA reviews, guidance that is likely to impact most major transportation projects.
• In February of this year, as part of its MAP-21 mandate, the Federal Highway Administration (FHWA) proposed a rule requiring states, as part of their risk-based asset management plans, to consider the risks from climate change and extreme weather.

One voluntary program developed by FHWA has gone a long way to assist states in the stewardship of their transportation assets. FHWA developed a framework to help guide states in performing an extreme weather and climate change vulnerability assessment. The vulnerability assessment identifies the most critical transportation infrastructure and then measures its level of exposure and resilience to extreme weather events and future projected climate variables. Understanding system and infrastructure vulnerabilities towards the development of cost-effective adaptation strategies is key to allocating scarce resources.

After developing the framework, FHWA announced a competition for funding and selected nineteen state DOT’s (or similar organizations) to participate in its Climate Change Resilience Pilot program. Tennessee, through the Tennessee Department of Transportation (TDOT), was one of those states selected. The Tennessee vulnerability assessment relied on the FHWA framework, but also developed its own unique methodology tailored to the needs of a state with a varied topography and major north-south and east-west transportation corridors for the nation. The project relied on historical weather data from the National Weather Service, future climate projections from the Coupled Model Intercomparison Project, and a state-wide survey and engagement of numerous transportation experts and stakeholders to gauge impacts from particular weather events and infrastructure combinations. It was an ambitious project that examined all transportation assets statewide, and served as a valuable screening tool to help planners understand where the most critical transportation infrastructure may be most vulnerable to extreme weather now and in the future. The results of the study can be used by the TDOT to better direct limited resources.

How can transportation agencies best address these risks, given the requirements of MAP-21 and the forthcoming FHWA final rule? Identifying vulnerabilities is an important start. FHWA has developed tools geared towards transportation agencies that can be used now.

• The CMIP Climate Data Processing Tool can be used to identify what types of precipitation and temperatures an area is likely to see in the future. Despite some limitations, these variables can be important, for example when selecting pavement binders or understanding what types of flooding an area is likely to experience in the future.
• FHWA also developed the Vulnerability Assessment Scoring Tool (or VAST). This is a more complex program but it can help an agency identify, compare, and rank vulnerabilities of specific assets based on certain indicators.
• Additionally, using data available from the National Weather Service can establish a baseline of extreme weather events that a locale has previously experienced and how the frequency and severity of those events are trending.

MPOs also might consider including a chapter on extreme weather in their long range plans. And, we always recommend watching for proposed rules and commenting on them. Involvement in rulemaking is the key to producing good rules that support an agency’s mission, rather than burden it.