Using National Household Travel Survey Data for the Assessment of Transportation System Vulnerabilities

Abstract

This paper describes how the National Household Travel Survey (NHTS) data can be used within the framework of the Threat and Hazard Identification and Risk Assessment, recently promulgated by the Federal Emergency Management Agency, to assess transportation system vulnerability. The purpose of this paper is threefold: identify common ground between the Department of Homeland Security and the Department of Transportation in methods of risk assessment; look specifically at transportation vulnerabilities by shifting the focus from transportation system infrastructure to the travel patterns and attributes of individuals; and with data from Honolulu, Hawaii, evaluate the vulnerability of transportation assets. The proposed transportation system vulnerability assessment method uses data from the 2001 NHTS Oahu, Hawaii, add-on survey and probable coastal inundation scenario for events caused by hurricane storm surge, inland flooding, and sea level rise. A geographic information system approach is used to simulate travel routes and assess the transportation system vulnerabilities for individuals and households. The NHTS data contain vital information regarding home, work, and other travel locations. The data also contain travel mode information that can be used to produce quantitative indices for exposure and vulnerability, which can be overlaid with plausible hazard and threat scenarios. Recommendations are made for improving the quality, availability, and usefulness of NHTS data for the reduction of risks. The findings are relevant to transportation research on risk assessment and threat and hazard reduction.