VTrans is Virginia's Transportation Plan. It is prepared for the Commonwealth Transportation Board by the Office of Intermodal Planning and Investment.

VTrans Vulnerability Assessment

VTrans identifies vulnerabilities of the Commonwealth’s Transportation infrastructure to flooding in coastal areas due to sea level rise and storm surge events, as well as inland flooding.

Background

In December of 2018, the Commonwealth Transportation Board took action to approve the VTrans Implementation Plan, which outlined key initiatives and specific actions to advance the VTrans Guiding Principles. The VTrans Vulnerability Assessment has been done in accordance with VTrans Implementation Plan item “to complete a resiliency assessment of Virginia’s multimodal network from a transportation planning perspective.”

Purpose and Limitations

This is a screening-level assessment of the vulnerability of Virginia’s transportation system, more specifically all public roadways and VDOT-maintained structures (bridges and culverts) covered in the National Bridge Inventory (NBI), to projected sea level rise, storm surge, and inland/riverine flooding scenarios. The focus is on identifying and conveying the relative magnitude of risks to the transportation system to:

  • Increase awareness;
  • Develop VTrans Strategic Actions to increase readiness; and,
  • Identify areas for data and research to improve accuracy and reliability of forecasted vulnerabilities.

The VTrans Vulnerability Assessment is not intended to be used to develop location-specific recommendations for the following reasons:

  • While this screening-level assessment narrows the universe of transportation infrastructure for further review, it does not replace the need for the collection of more precise location-specific data.
  • The transportation system is one of the many infrastructure components impacted by the forecasted vulnerabilities. Therefore, it would be advisable to conduct a more comprehensive area-wide assessment for all components of physical and social infrastructure as some vulnerability mitigation strategies might require systematic solutions such as perimeter protection.

Draft Definitions of Vulnerability and Resiliency

  • Vulnerability: Vulnerability is a function of exposure to a hazard(s), the sensitivity to the given hazard, and adaptive capacity or the system’s ability to cope.
  • Resiliency: Resiliency is the capability to anticipate, prepare for, respond to and recover from extreme weather event(s) with minimum damage to social well-being, infrastructure, the economy, and the environment.

The definition of vulnerability is based on the Federal Highway Administration (FHWA) definition that breaks down vulnerability as a function of an asset or system’s exposure, sensitivity, and adaptive capacity

Methodology and Draft Results

VTrans Vulnerability Assessment focuses on flooding risks associated with three hazards: (1) sea level rise; (2) storm surge; and, (3) inland/riverine flooding.

Several factors influence the extent and frequency of exposure to sea level rise, storm surge, and inland/riverine flooding. To account for uncertainty in the projections, three scenarios were developed to explore a broad range of futures to provide a range of vulnerability. This Vulnerability Assessment applied the three (3) scenarios to each of the three (3) hazards, resulting in a total of nine (9) location-specific Vulnerability Scores.

  • Policy uncertainty: globally, countries are making commitments that may potentially reduce frequency and intensity of extreme natural events. However, there are uncertainties around timeframes for implementation and adherence to the commitments.
  • Scientific uncertainty: Available literature indicates that the understanding of complex natural systems that govern climate is evolving. This imperfect understanding introduces another source of uncertainty.
  • Model uncertainty: Even with a good understanding of scientific processes, it is difficult to represent them, leading to a third source of uncertainty.

The detailed methodology for this assessment, as well as additional background information, can be found in the Draft VTrans Vulnerability Assessment Technical Memorandum. This document is directed towards practitioners or others who would like to know more details about the methods and procedures.

Frequently Asked Questions

Looking for more answers to specific questions about VTrans Vulnerability Assessment? Find more information on our Frequently Asked Questions page here: https://vtrans.org/get-involved/frequently-asked-questions.