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Adaptation to Extreme Weather Events
State Departments of Transportation (DOTs) manage a diversity of extreme weather events every year, including dust storms, blizzards, and hurricanes. In May of 2013, the American Association of State and Highway Officials (AASHTO) convened a national symposium for state DOTs to share experiences with extreme weather and exchange best management practices. Examples of practices recommended by DOTs include:
A perception exists that adaptation will require large, expensive projects that transportation agencies must fund in addition to meeting existing service requirements and regulations. In certain cases, adaptation does require large capital investments. However, most adaptation activities currently underway are incremental shifts in decision making and tweaks to best management practices. Mainstreaming consideration of weather and climate data into day-to-day management is a highly successful and low cost way to begin increasing resilience.
Adaptation strategies span a range of options, from data collection and monitoring to project design and investment decisions. Certain high risk contexts may demand a large-scale capital investment solution (such as coastal protection), while other contexts may be best addressed with slight modifications to existing best practices. For example, a transportation agency may choose to maintain culverts more regularly and with a focus on high vulnerability areas, rather than installing larger storm water drainage structures. In certain cases, an agency might even choose to accept periodic failure of an asset due to extreme weather if the consequences of that failure are minimal and easily repaired. Optimal adaptation solutions are diverse and highly dependent on local priorities, asset characteristics, and expected remaining design life.
This section discusses examples of how adaptation is being mainstreamed into existing decision-making processes, including asset management, long-range transportation planning, design and construction, operations and maintenance, and emergency management. For a summary of adaptation activities identified and information about the adaptation activities, please see Table 5 and Table 6 in Appendix A. Note that while this report catalogs a detailed sampling of current and recent adaptation measures, there may be additional adaptation initiatives underway within the United States and abroad.
Transportation Asset Management (TAM) is an emerging business strategy for making improved, data-driven investment and maintenance decisions. TAM encourages agencies to specify goals, develop monitoring programs, and track performance over time. TAM systems are invaluable for vulnerability assessments because they often collect, integrate, and manage data (such as asset condition) that can be used to evaluate the vulnerability of assets to climate change. In addition, transportation agencies with strong TAM systems in place are also better able to monitor the effectiveness of adaptation measures (Meyer et al. 2012).
Many of the adaptation strategies identified in this section straddle distinctions between vulnerability assessment and adaptation. Key strategies include:
Several transportation agencies are already implementing these tactics. For example, the Metropolitan Atlanta Rapid Transit Authority (MARTA) is incorporating climate change vulnerability into several existing decision-making frameworks. MARTA is adding a field to its Enterprise Asset Management System to track whether assets are sensitive to climate, adding a climate-related objective to its resource allocation decision-making software (which also tracks objectives such as safety and state of good repair), and will incorporate climate impacts in the Asset Management Plan update (FTA 2011).
Washington State Department of Transportation's (WSDOT) Bridge Office is also integrating climate change into their bridge management system, Bridge Engineering Information System (BEIS) (FHWA 2012b). As part of a statewide, multi-modal vulnerability assessment pilot project, WSDOT combined sea level rise inundation maps with existing information from BEIS on bridge locations, plans, rating reports, and inspection reports to help staff qualitatively rate bridge condition and climate impacts (WSDOT 2011).
In response to major flooding from Hurricane Irene, Vermont Agency of Transportation (VTrans) used its previously compiled culvert inventory to quickly map all damaged locations (FHWA 2012b). Furthermore, VTrans is making improvements to the Vermont On-line Bridge and Culvert Inventory Tool to allow for integration of assessments of culvert and bridge conditions with screening of geomorphic compatibility with channels to help prioritize infrastructure needs (VTrans 2012). This tool will help VTrans effectively target adaptive upgrades to highly vulnerable infrastructure.
The Maryland State Highway Administration (MD SHA) is collecting climate information, such as sea level rise mapping, and integrating all asset information into one GIS-based system to manage for climate change (FHWA 2012c). The MD SHA used 2011 road closure coordinates to map closures by cause, such as high water, debris, winter precipitation, or other type of incident (FHWA 2012d). During Hurricane Sandy, the State Emergency Management Agency used this GIS data layer to identify potential hazards and improve storm response.
As transportation agencies begin to consider adaptation to future climate (rather than adaptation to existing climate variability), a key step is integrating climate risk into long-range planning. Metropolitan Planning Organizations (MPOs) are required to write metropolitan transportation plans (MTPs) that address long-term and short term transportation strategies for the region over at least a 20 year planning horizon. The Transportation Improvement Program (TIP) is a five-year work plan that includes a list of projects drawn from the MTP that are planned and feasible in the near term for a metropolitan region.
All of the projects included in a region's TIP are encompassed into the State Transportation Improvement Program (STIP), in addition to a project list developed by the state DOT for rural regions not covered by an MPO. Because the planning process is forward thinking, and has implications that stretch decades into the future, integrating consideration of vulnerability and adaptation into long-range transportation plans (LRTPs) is an important strategy for addressing the long term impacts of climate change.
There are not many MPOs or state DOTs using climate change adaptation or vulnerability as a factor in prioritizing transportation projects as part of the project selection process to move projects from the transportation plan into the TIP. The Boston Region MPO is one example of an MPO that incorporates resilience into project selection, giving points for projects that improve the ability to respond to extreme conditions (Boston Region MPO 2013b).
A discussion of adaptation to climate change is beginning to make its way into more and more long-range planning documents. Transportation agencies are increasingly considering the following adaptive tactics:
The Boston Region MPO developed an interactive natural hazards mapping tool that links to the MPO's database of TIP projects (Boston Region MPO 2013a, FHWA 2012a). The tool can be used to determine whether proposed projects are located in areas exposed to flooding, storm surge, or sea level rise. Hampton Roads Transportation Planning Organization, the MPO for the Chesapeake, VA, region, released their 2034 LRTP in January 2012. The Plan acknowledges and discusses in detail the affect that sea level rise from climate change will have on the region's transportation infrastructure. Furthermore, the Plan states that "adapting to the impacts of climate change, specifically sea level rise, may in the long run require moving or rebuilding some of the region's roads." However, adaptation is not specified as being a factor that is considered in prioritizing projects. Rhode Island's state LRTP also addresses adaptation to sea level rise. In the Plan's environmental analysis section, there is discussion of the effect that sea level rise will have on the state's transportation system. Within the policies suggested in the environment category, the Plan also suggests that the state acknowledge the threat that sea-level rise poses, and plan infrastructure improvements with that in mind. Within the planning category, one of the strategies for the state is to obtain digital elevation data on sea-level rise and use the data to assess adverse impacts on the state's transportation infrastructure.
The U.S. Forest Service at Olympic National Forest (ONF) evaluated ways to incorporate climate change conditions into the Road Management Strategy (RMS), a tool to compare the risks that a road segment poses to various resources against the criticality of that road. The analysis helps prioritize roads for maintenance, upgrading, and decommissioning (USFS 2011). The Forest Service recognizes that this type of prioritization and planning is crucial because funding allocated for road maintenance is limited.
The Virginia Department of Transportation (VDOT), in partnership with the University of Virginia and the Hampton Roads Planning District Commission, conducted a vulnerability assessment study to analyze how priorities in the Hampton Roads Transportation Planning Organization's LRTP may change under climate change scenarios (VDOT 2012). The project team developed a multi-decision model to rank and reprioritize the LRTP's proposed transportation projects and multi-modal policies based on future climate factors and other non-climate planning considerations.
Weather variables, such as temperature and precipitation assumptions, are often inputs into infrastructure design decisions. For example, the design of storm water drainage systems, airport runways, and bridges all reflect standards for coping with rainfall and heat conditions. These designs are based on statistical analysis of historical weather patterns as well as an assessment of risk and cost tradeoffs. Since design metrics are based on the historical climate, they reinforce the concept of "climate stationarity," or the assumption that the frequency and magnitude of weather patterns will remain unchanged into the future.
Very few agencies in the United States have explicitly required design changes in anticipation of future climate change, but many agencies have retrofitted or rebuilt assets based on recent experiences with extreme weather. A key consideration for most agencies is that upgrading design standards, or building for more extreme events, can increase project costs. In addition, state DOTs do not feel that climate model outputs have sufficiently high resolution or level of certainty to be directly incorporated into designs. However, there are a number of adaptation actions that agencies have taken to increase resilience, even in the face of data gaps and uncertainty:
Agencies around the world are already implementing these tactics in order to increase infrastructure resilience. The California Department of Transportation is beginning to screen proposed roadway structures in the project initiation phase to identify potential sea level rise vulnerabilities and determine the need to incorporate adaptation measures (Caltrans 2013). In the case of the South Coast 101 High Occupancy Vehicle Lane Project, the DOT evaluated sea level rise vulnerabilities in the project's draft environmental impact report. The project development team identified three locations within the project limits that could be exposed to a 55-inch sea level rise scenario projected for 2100. However, the team determined that adjustments to the project were not necessary because the design life of the bridges would be exceeded by the year 2100 (i.e., the design life was less than 88 years).
In New England, the Piscataqua Regional Estuary Partnership (PREP) is reaching out to local transportation stakeholders in Maine and New Hampshire to promote culvert and bridge design standards that allow passage of aquatic organisms and stream connectivity, as well as sufficient capacity to prevent catastrophic failures during floods (PREP 2010). PREP used evaluation methods to analyze the roads and culverts affected by changes in rainfall and extreme storm events and prioritize stream crossings for repair or redesign.
After facing severe flooding and stream-related erosion impacts to road infrastructure during Hurricane Irene, the Vermont Agency of Transportation (VTrans) is employing a new approach for considering hydraulic capacity in design (Meyer et al. 2013). VTrans is using hydrologic and hydraulic modeling and slope mapping to incorporate stream and slope stability into road design. Additionally, VTrans has re-designed their approach for repairing slope sections adjacent to rivers. Rather than placing stone to stabilize the slope, engineers are building the slope to match stable channel dimensions.
The Connecticut Department of Transportation (ConnDOT), funded by the FHWA Climate Resilience Pilot Project, is revisiting current hydraulic design standards for bridge and culvert structures. Although Connecticut has experienced impacts to transportation infrastructure from frequent and intense extreme rainfall events in recent years, the current design standards reference rainfall data that have not been updated in decades. ConnDOT is conducting an inland flooding vulnerability assessment that will compare the hydraulic capacity of bridges and culverts using the older rainfall data versus the more recent rainfall data. The project team will make recommendations about whether design standards should be updated.
Iowa DOT is selectively retrofitting overflow bridges in order to account for localized, extreme flooding events. In addition, the DOT is building a new levee to channel flood waters away from the bridge abutments of an important highway bridge in Des Moines, thereby protecting the bridge structure. While the state does not have enough resources to maintain a regular retrofit program, they are upgrading structures opportunistically when possible (Choate et al. 2012).
Outside of the United States, London's major new rail project, Crossrail, has built in adaptation measures intended to help ensure continuity of service within the project's 120-year design life (FTA 2011). Crossrail's design standards are set to withstand a 1-in-200-year flood and include measures ranging from raised entry and egress levels to active flood gates and stop logs. Air conditioning is also built into the design of the project's trains and platforms to cope with projected higher temperatures.
Strategies for Effective Implementation: Opportunistic Adaptation and Adaptation as a Co-Benefit
Participants at the 2011-2012 FHWA Adaptation Peer Exchanges found that it is easier to communicate and justify the need for activities and programs in which adaptation is opportunistic, and increased resilience to climate change is just one of several benefits (FHWA 2012a).
Opportunistic adaptation. Transportation agencies often take advantage of key opportunities to build additional resilience into assets or systems. For example, an agency may rebuild a damaged culvert to a larger size in order to increase its capacity to better handle future flood events.
Adaptation as a co-benefit. Some of the most successful examples of adaptation are projects that have reduced climate risk as a co-benefit, rather than as the primary purpose of the project. For example, District 4 of the California Department of Transportation (Caltrans) recently relocated a section of Route 1 in the Devil’s Slide region of San Mateo County, which frequently faced closure and repair due to rockslides and land slippage from adjacent steep slopes (Caltrans 2013). The relocation of two tunnels beneath a mountain will have the added benefit of helping to avoid increased erosion, landslides, or flooding that could be caused by climate change.
Each transportation agency possesses a set of best practices that already improve resilience to climate variability and change. Many of these best practices have evolved as a result of experiences with extreme weather. For example, Alabama DOT switches maintenance crews to earlier start times in the summer when there are more frequent extreme heat events. Michigan DOT has iteratively improved methods for dealing with winter storms, particularly lake effect snow. The agency has invested in tow plow technology, expanded anti-icing efforts prior to expected storms, and increased their salt use efficiency by mixing it with sand and distributing it at a lower speed to reduce bounce and scatter of the salt into ditches. Transportation agencies iteratively improve their management of extreme weather through the development of best practices, thereby increasing their resilience to extreme weather.
In the immediate term, tweaking existing practices can be a low cost, highly certain way of reducing vulnerability to climate change. Some transportation agencies, such as New Jersey DOT, are using debriefs and other strategies to make sure that every extreme weather event is an opportunity for improvement.
Transportation agencies are continuously tweaking best management practices to better maintain and operate road systems. These adaptations span a range of activities, including:
Transportation agencies are already implementing these adaptive operations and maintenance tactics. For example, the Southeastern Pennsylvania Transportation Authority (SEPTA) has accelerated their tree trimming program in recent years in response to lessons learned in previous storm events (ICF ongoing).
Transportation agencies are also looking for ways to use operations and maintenance practices to build resilience over the long-term. Michigan DOT is piloting a maintenance decision support system along a major interstate corridor (Meyer et al. 2013). The DOT is also identifying ways to bring roads back to safe operation more quickly after snow storms, such as changing the types of salts used for ice removal. To cope with soil erosion and landslides, Caltrans is installing subsurface drainage facilities, constructing rock buttresses, inserting reinforcement bars to stabilize steep slopes, and planting erosion control grasses (Caltrans 2013).
To better manage the risk of high temperatures, Amtrak will upgrade a section of overhead electrical wire that tends to sag and tighten in variable temperatures (Amtrak 2011). Intermediate support structures for the catenary wires that power a stretch of track between Trenton and New Brunswick, New Jersey, will be installed to shorten the spans between supporting poles. The Amtrak infrastructure upgrade will improve service reliability and increase resiliency to extreme temperatures in the process.
In response to high temperatures, Transport for London painted the tops of bus white in order to reflect heat and help keep the vehicles cool even if air conditioning units on board malfunction. Transport for London also specified that all buses feature upper deck ventilation systems and tinted windows that can open.
As extreme weather events increase in magnitude and frequency, transportation agencies are working to become more agile and resilient. Agencies are also learning from recent extreme events and improving protocols in order to restore service more quickly. Such tactics include:
The Metropolitan Transportation Authority (MTA) Hurricane Plan details maintenance operations protocols such as moving equipment (e.g., rail cars and buses) from low-lying areas or vulnerable outdoor tracks; staging recovery equipment such as generators and chainsaws near areas where they would be needed; and clearing catch basins and sewer lines (NYC MTA 2012a).
In response to extreme lake effect snow storms, the Michigan DOT has changed their strategy for operations and management logistics such as the number of employees assigned to weather response, the numbers and start times of shifts, use of temporary winter employees, and the need for staff lodging when the weather is so bad staff members cannot return home after their shift (Meyer et al. 2013).
Communicating with transportation system users is an immediate adaptation measure that can be deployed prior to, during, and after an extreme weather event. Caltrans has been using real-time message signs and portable signs along roads as well as other communications technologies to indicate road closures during extreme events (Caltrans 2013). Similarly, Missouri DOT (MoDOT) uses a wide range of communication channels including cell phones/texting, e-updates, Facebook updates, Twitter, and Sirius Radio to ensure they reach a wide audience (Meyer et al. 2013). Furthermore, MoDOT reaches the target audience of commercial vehicle operators through communications capabilities of other organizations including trucking associations.
Keeping the public aware is particularly important during emergency events. The New York Metropolitan Transportation Authority (MTA) upgraded its communications technology after a heavy rain event forced a temporary shutdown of the New York City subway system and affected two million transit users. The agency acquired the ability to send out one million simultaneous email alerts, expanded the server capacity of its website, and improved information feeds, public address systems, and information screens that can operate under emergency conditions (FTA 2011).
In order to quickly recover from major flooding damages from Hurricane Irene, VTrans used an incident command system (ICS) decision-making framework to manage a coordinated response among a large number of jurisdictions and functional agencies (Meyer et al. 2013). Incident command centers (ICCs) were established in different regions affected by the storm and received directions regarding priorities from a Unified Command (UC) in the state capital.