Macroscopic Fundamental Diagrams According to the Different Flood Depths on Probe Vehicle Data in Urban Bangkok

Impact of flood depth on traffic volume in two different zones of the Bangkok road network was investigated using traffic data obtained from probe vehicle trajectories. A Macroscopic Fundamental Diagram (MFD) was utilized to compare traffic flow rates across two road network zones in the city for a variety of flood depths, namely 0-5 cm, 5-10 cm, 10-15 cm, 15-30 cm, and more than 30 cm. Results of empirical analysis over an observation period of one year as 2019 showed that flood depths had a strong correlation with the MFD parameters of free-flow speed, maximum flow, and traffic jam density. In particular, road floods greatly reduced average maximum flow across the inner city road network in Bangkok. Road floods had a significant impact on traffic characteristics of urban road networks.