The temporal nature of flood impacts on traffic is assessed using the flood model HEC-RAS and the micro-scale traffic model SUMO. The 2013 flood in Calgary, Canada is used to demonstrate the direct, indirect and cascading impacts, and identify short and medium scale temporal patterns. The addition of rainfall is considered through nine different scenarios before, during and after the flood. A penalty model is proposed that realistically models the indirect impact to traffic. For all static and dynamic simulations, the flood increases time delay roughly 12-65%, increases distances travelled by 30-45%. With the addition of rain, the delays increase further by 2-15% and distances by roughly 14%, respectively. The delay across these simulations experienced increases in the range of 10-68% (average 24%) with the inclusion of the penalty. A theoretical concept that identifies indirect and cascading impacts of flood and rainfall on transportation in flood impact assessments is proposed. • Flood impacts during rainfall are modelled with a staged progression, in the pre-flood with rainfall, flooding, staged flooding, and recovery of the network with receding flood water periods using a hydrodynamic model HEC-RAS and the microscopic traffic model SUMO. • Proposing a new penalty-based adjustment method for unmet trips in traffic simulation. • Theoretical concepts that provide a structured interpretation of direct, indirect, compounded and cascading impacts.
Rebally et al. (Sun,) studied this question.