Traffic Evacuation Simulation and Development of Contingency Plan for a Flood-Prone Community in Puerto Rico

Abstract

Puerto Rico faces a constant risk of flooding due to its geographic location and the recurrence of extreme weather events such as tropical waves, cold fronts, and hurricanes. The Lucchetti community, located in the municipality of Yauco, exemplifies this vulnerability as it lies within the main channel of the Yauco River, an area historically affected by overflow and flooding events.This study aimed to analyze the flood dynamics and vehicular evacuation process in the Lucchetti urbanization in order to assess its vulnerability to extreme events and propose strategies to improve community response times and evacuation capacity.An integrated modeling approach was developed, combining hydrologic, hydraulic, and traffic simulation tools. In the first stage, the hydrologic and hydraulic behavior of the watershed was modeled using HEC-HMS and PCSWMM, incorporating the rainfall recorded during Hurricane María (2017). The watershed was delineated using a digital elevation model processed in HEC-HMS, while the average slope and flow path length were computed in ArcGIS Pro. The resulting hydrographs were exported to PCSWMM to simulate river overflow and the two-dimensional propagation of floodwaters across the community, using a 10-meter resolution mesh and natural drainage conditions.The results show that the model realistically reproduces the flooding observed during Hurricane María, reaching maximum water depths of up to 1.8 meters in critical areas of the community. From the moment the river overtops its banks until floodwater reaches 0.3 meters over the evacuation route, the available evacuation time is approximately 1 hour and 17 minutes, indicating a highly constrained response window for residents.In the second phase, a microsimulation of vehicular evacuation was performed using SUMO (Simulation of Urban Mobility) to analyze and optimize traffic flow under emergency conditions. Using real traffic data and the road network obtained from OpenStreetMap, several management strategies were evaluated. The implementation of a secondary evacuation route reduced the total evacuation time (1 h 5 min 57 s) by 53%, while the use of a traffic signal or manual control (traffic guard) achieved a 55% reduction.The findings demonstrate that the integration of hydrologic, hydraulic, and traffic models is an effective tool to strengthen community resilience and flood risk management. This approach supports the development of evidence-based emergency plans, helps optimize evacuation times, and provides technical guidance for municipal and state decision-making. Moreover, the proposed methodology is replicable and adaptable to other vulnerable communities in Puerto Rico and similar tropical regions, offering a transferable framework to enhance community response capacity and promote sustainable climate change adaptation strategies.

Keywords: Flood modeling, Evacuation simulation, Risk management, PCSWMM, HEC-HMS, SUMO, Hurricane María, Puerto Rico.

DOI: 10.54941/ahfe1007167