  Urban flooding disrupts traffic networks, affecting the mobility and
disrupting access of residents. Since flooding events are predicted to increase
due to climate change, and given the criticality of traffic networks,
understanding the flood-caused disruption of traffic networks is critical to
improve emergency planning and city resilience. Leveraging high-resolution
traffic network data from a major flood event and advanced high-order network
analysis, this study reveals characteristics of the anatomy of perturbed
traffic networks. First, the findings show network-wide persistent increased
travel times could last for weeks after flood water has receded, even after
modest flood failure. During disaster event period, modest flooding of 1.3%
road segments caused 8% temporal expansion of the entire traffic network. The
results also show distant trips would experience a greater percentage increase
in travel time. Also, the extent of increase in travel time does not decay with
distance from inundated areas, suggesting that the spatial reach of flood
impacts extends beyond flooded areas. Departing from the existing literature,
which primarily informs about physical vulnerability in road networks to
floods, the findings of this study provide important novel understanding of
floods impacts on the functioning of traffic networks in terms of travel time
and traffic network geometry. The persistent travel time increase in the entire
network can translate to significant social and economic impacts in terms of
user costs, additional CO2 emissions, and lost productivity. Due to the
importance of traffic networks functioning for the operation of cities, the
results have significance implications for city managers, transportation
planners, and emergency managers to deal with the impacts of urban flooding.
