Tsuyoshi Takano, Hiroyoshi Morita, Piamsa-nga Napaporn, Varameth Vichiensan, Shinichiro Nakamura

Received 12 July, 2023
Accepted 24 September, 2023
Published online 8 December, 2023

Tsuyoshi Takano¹⁾, Hiroyoshi Morita¹⁾, Piamsa-nga Napaporn²⁾, Varameth Vichiensan³⁾, Shinichiro Nakamura⁴⁾

1) Dia Nippon Engineering Consultants Co. Ltd, Nagoya, Japan
2) Department of Water Resources Engineering, Kasetsart University, Bangkok, Thailand
3) Department of Civil Engineering, Kasetsart University, Bangkok, Thailand
4) Department of Civil and Environmental Engineering, Nagoya University, Nagoya, Japan

In Asian megacities undergoing rapid urbanization such as Bangkok, heavy rainfall exacerbates traffic congestion owing to inadequate drainage systems. This study statistically analyzed the extent to which rainfall affects urban traffic speed and how this impact varies depending on regional environmental factors and traffic demand trends, utilizing probe vehicles and rainfall data from 2018 to 2020 in Bangkok. The results clearly indicate that both the intensity of rainfall during driving and previous cumulative rainfall significantly reduce traffic speed. This impact is particularly pronounced during morning and evening rush hours, and in areas with a high proportion of narrow roads or in low-lying areas. On the other hand, areas with rich urban green space, which naturally absorb and retain water, tend to mitigate the speed reduction due to rainfall. This study highlights the fact that the impact of rainfall on traffic varies with time and location, suggesting that the exacerbation of rain-induced congestion can be more effectively mitigated by coordinated improvements in drainage facilities, traffic management and land use.

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Copyright (c) 2023 The Author(s) CC-BY 4.0