Effects of Inclement Weather on Traffic Flow and Breakdown Probability: Findings from St. Louis, MO

Abstract: Macroscopic traffic stream models describe the relationship between fundamental traffic flow parameters and are used to develop traffic control algorithms, establish performance measure thresholds, and determine roadway capacity. Over the past eight decades, researchers have extensively studied the relationship between traffic flow parameters and offered various models to describe the traffic stream. However, very few studies have investigated the impact of inclement weather on these relationships, even though adverse weather conditions have the potential to affect traffic flow. This paper contributes to the limited body of knowledge on the impact of weather on the traffic stream by developing traffic models and breakdown probability distributions for four active bottlenecks on the St. Louis, Missouri, USA freeway network.
This paper aims to answer the question of how inclement weather impacts traffic flow. This work is distinguished from previous research by its utilization of a Weather Surveillance Radar 1988 Doppler to measure precipitation in the vicinity of the active bottlenecks. To the best of the authors' knowledge, this is the first effort to develop weather-aware traffic stream models using high-resolution and localized weather data. This paper investigates the common traffic models, Gipps, Newell–Franklin, and van Aerde, to describe traffic stream characteristics during normal and adverse weather conditions. Breakdown probability models are developed utilizing Gompertz, Logistic, 𝑡-location scale, and Weibull distributions, and traffic flow rates corresponding with various breakdown likelihoods are discussed. This work is in progress, and the full paper, including the findings and the results, will be submitted for review by the December 15th deadline.