U.S. Department of Transportation's Vulnerability Assessment Scoring Tool (VAST)
The U.S. Department of Transportation's Vulnerability Assessment Scoring Tool (VAST) is an Excel-based tool designed to help transportation planners conduct a quantitative, indicator-based screening of transportation system vulnerabilities to climate stressors. It is intended for use by state departments of transportation (DOTs), metropolitan planning organizations (MPOs), and other transportation organizations and agencies, to help these agencies efficiently assess vulnerabilities and prioritize assets.
VAST relies on indicators (such as asset characteristics or changes in temperature or precipitation averages, or frequency or severity of extreme events) that can help agencies assess vulnerability of these assets. Vulnerability is scored as a function of three components:
- Exposure: potential exposure of assets to climate stressors, using indicators based on climate projections like number of extreme heat days, sea-level rise inundation maps, and 100-year 24-hour rainfall events.
- Sensitivity: how sensitive the asset is if exposed to particular climate stressors, using indicators related to asset design like bridge height or culvert size.
- Adaptive capacity: how well the system can adjust to disruption, using indicators such as detour length.
Depending on the desired scope of the vulnerability assessment, transportation agencies select the indicators to use for each of these three components, collect data about those indicators, and then convert the data into vulnerability scores. VAST allows users to adjust scoring to weight the three components differently as desired and appropriate for the scope of their assessment. Transportation agencies can use the findings and vulnerability scores to help prioritize which specific assets or asset types require adaptation measures.
VAST was developed to be a flexible tool, accommodating variability in the amount of information available about specific assets in a transportation system, and allowing for agencies to mix hard data with local expertise in assessing vulnerability (such as by adjusting the weighting of the exposure, sensitivity, and adaptive capacity component scores to affect the overall vulnerability score).
VAST is designed to be compatible with USDOT's other tools for climate adaptation, including the asset criticality guidance (which helps agencies identify their most critical assets to prioritize) and the sensitivity matrix (which identifies relationships between key asset types and climate stressors). These tools can be used at different stages (modules) in the FHWA Adaptation Framework for Vulnerability Assessment.
If you have any trouble accessing the website link above to the Excel-based tool, please find here an archived page. https://web.archive.org/web/20170125182304/https://www.fhwa.dot.gov/environment/sustainability/resilience/adaptation_framework/modules/scoring_tools_guide/vast.xlsm.
Publication Date: 2015
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