  Recurrent flooding has increased rapidly in coastal regions due to sea level
rise and climate change. A key metric for evaluating transportation system
degradation is accessibility, yet the lack of temporally and spatially
disaggregate data means that the impact of recurrent flooding on accessibility,
and hence transportation system performance: is not well understood. Using
crowdsourced WAZE flood incident data from the Hampton Roads region in
Virginia, this study (Part 1) examines changes in the roadway network
accessibility for travelers residing in 1,113 traffic analysis zones (TAZs)
across five time of day periods. Additionally, a social vulnerability index
framework is developed to understand the socioeconomic characteristics of TAZs
that experience high accessibility reduction under recurrent flooding.
  Results show that TAZs experience the most accessibility reduction under
recurrent flooding during the morning peak period (6 to 9am) with large
differences across different zones, ranging from 0 to 49.6 (percentage) for
work trips (with population weighted mean reduction of 1.71 percent) and 0 to
87.9 (percentage) for nonwork trips (with population weighted mean reduction of
0.81 percent). Furthermore, the social vulnerability analysis showed that zones
with higher percentages of lower socioeconomic status, unemployed, less
educated, and limited English proficiency residents experience greater
accessibility reduction for work trips. In contrast to previous studies that
aggregate the effects of recurrent flooding across a city, these results
demonstrate that there exists large spatial and temporal variation in recurrent
floodings impacts on accessibility. This study also highlights the need to
include social vulnerability analysis in assessing impacts of climate events,
to ensure equitable outcomes as investments are made to create resilient
transportation infrastructure.
