Contacts
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The Federal Highway Administration’s (FHWA)’s Climate Resilience Pilot Program seeks to assist state Departments of Transportation (DOTs), Metropolitan Planning Organizations (MPOs), and Federal Land Management Agencies (FLMAs) in enhancing resilience of transportation systems to extreme weather and climate change. In 2013-2015, nineteen pilot teams from across the country partnered with FHWA to assess transportation vulnerability to climate change and extreme weather events and evaluate options for improving resilience. For more information about the pilots, visit: http://www.fhwa.dot.gov/environment/climate_change/adaptation/
Broward Metropolitan Planning Organization (MPO), Miami-Dade MPO, Palm Beach MPO, and the Monroe County Planning and Environmental Resources Department partnered to conduct a detailed vulnerability assessment of transportation infrastructure in a four-county region in South Florida. The region’s flat, coastal landscape makes it among the most vulnerable in the country to the effects of sea level rise, storm surge, and rain-driven inundation. This study conducted a detailed geospatial analysis and developed a system to determine vulnerability scores for “regionally significant” road and rail segments in the region. Moreover, the study recommended several ways for partner agencies to incorporate the vulnerability results into their normal decision-making processes such as transportation planning, project prioritization, project rehabilitation or reconstruction, new project design, system operations, and system maintenance.
The project study area covered Broward, Miami-Dade, Palm Beach, and Monroe Counties, all located in southeast Florida. The vulnerability assessment focused on the area’s “regionally significant” freeways, arterials, and rail (as defined by the Southeast Florida Transportation Council) to three climate stressors: sea level rise, storm surge and related flooding, and heavy precipitation and related flooding.
The project defined five key objectives to guide the analysis:
This project took a geographic information system (GIS)-intensive approach to determine vulnerability scores for individual segments of the roads and rail lines analyzed. Then, the project team recommended several adaptation strategies, designed to integrate consideration of climate change risks into everyday decision-making processes at the partner agencies. The project also established a technical advisory committee representing 32 agencies to provide guidance on the overall technical approach and study recommendations
The approach featured three primary elements:
"One of the key challenges in the technical analysis was that various agencies applied different representations of the South Florida land form in their systems… The study spent considerable time coordinating with various agencies to assess risks in their respective jurisdictional area and to identify the varying data sources potentially available to conduct the vulnerability assessments."
—South Florida Climate Change Vulnerability Assessment and Adaptation Pilot Project Final Report
Compile and Clean Data. This project had the benefit of several available datasets—ranging from LiDAR-derived elevation data, Federal Emergency Management Agency (FEMA) flood zone maps, sea level rise inundation maps, and data on the regional transportation network. However, compiling, reconciling, and cleaning these datasets took considerable resources—in terms of GIS expertise as well as computer processing time. Necessary data processing steps included:
Calculate Vulnerability Scores. Following the FHWA Vulnerability Assessment Framework and examples from other projects (e.g., U.S. DOT’s Gulf Coast Study Phase 2), the South Florida team defined vulnerability as a function of three components or categories—exposure, sensitivity, and adaptive capacity—and calculated vulnerability scores for each segment using indicators of each category.
Exposure – The project team used three indicators to calculate each segment’s exposure score: (i) the percentage of the segment permanently inundated by sea level rise, (ii) its current “flood inundation exposure index,” and (iii) its future “flood inundation exposure index.” The current flood inundation exposure index reflects whether an asset is currently inundated in the FEMA 100-year flood plain and the depth of that inundation. The future flood inundation exposure index reflects the distance from the segment to the closest existing FEMA flood zone, and the difference in elevation between that segment and the FEMA flood zone.
Sensitivity – For roads, bridge scour rating and substructure condition rating served as indicators of sensitivity, or the capacity of the asset to deal with changes in a climate stressor. The project team did not evaluate sensitivity for rail assets, since no relevant data were available.
Adaptive Capacity – To capture adaptive capacity—the ability of the transportation network to deal with the loss of an impacted asset—the team considered average annual daily traffic and detour length for roads, and Tri-Rail ridership for rail.
Vulnerability – The South Florida team then calculated vulnerability scores for each segment as a weighted average of its exposure, sensitivity, and adaptive capacity. The weights applied are shown in Table 1. The team chose to weight exposure higher than the other categories.
Link Results to Decision-Making. Finally, the project team identified five types of major transportation decision-making processes in the region that are directly related to the potential disruptions from future inundation: transportation planning and prioritization, rehabilitation or reconstruction of existing facilities in high risk areas, new facilities in new rights-of-way in high risk areas, system operations, and systems maintenance. For each of these decision-making areas, the project team recommended ways to integrate knowledge of climate change vulnerabilities into those decisions.
The vulnerability assessment data analysis resulted in vulnerability scores for each regionally significant road and rail segment in the four-county study area. An example output of the analysis is shown for Miami-Dade County in Figure 2.
The project team’s recommendations for linking this information to decision-making include:
Transportation Policy, Planning and Project Prioritization
Rehabilitation or Reconstruction of Existing Facilities in High Risk Areas
New Facility on New Right-of-Way in High Risk Areas
Operations
Maintenance
Data availability and quality are critical. Climate adaptation studies need to consider what types of data will be needed, what types of data are available, and what surrogates can be used if data are inadequate or unavailable. Transportation agencies should collect relevant data (e.g., bridge approach elevation, size of hydraulic openings) periodically or as part of normal activities to streamline future risk analyses.
Database integration is difficult, but also critical. A regional analysis like this project requires consistent and combined data sets. Although the number of relevant studies that preceded this one was an advantage, it also created significant challenges to combine the data so they could be used in a single analysis. The data used in this project required substantial “cleaning” and quality control before they could be used in calculations.
Establish agreements among participating agencies early in the process. The multi-agency technical advisory committee provided an important source of input and guidance for this study. However, marshalling the resources of many different agencies (even just to participate in the planning process) can be challenging. For future projects, agreements and understandings among the major participants should be put in place as early as possible.
Establish a long-term commitment to ongoing climate adaptation planning. Given the long time frame and uncertainty of climate change stressors, and the longevity of many transportation assets, the climate change adaptation process cannot be a one-time effort, but rather something that happens continuously over time and is integrated into the normal planning and decision-making process.
Following this project, member agencies intend to consider the study’s recommendations and incorporate climate change into their ongoing decision-making processes. Among the recommendations identified above, possible next steps include:
www.fhwa.dot.gov/environment/climate/adaptation/2015pilots/
Becky Lupes
Sustainable Transport & Climate Change Team
Federal Highway Administration
Rebecca.Lupes@dot.gov, 202-366-7808
