Effects of Rain on Traffic Operations on Florida Freeways

Abstract

Although the correlation between traffic variables and weather appears to be intuitive, quantifying the effects that weather, especially rain, has on driver response in travel speeds and traffic demands is needed to evaluate practical aspects of traffic operations. Previous studies have researched driver responses to inclement weather on freeways located in northern regions of the United States and Canada. However, driver familiarity with local weather conditions is a factor that should be considered in determining inclement weather effects on traffic variables. The focus of this research was to examine driver response to rain precipitation on freeways located in the southeastern regions of the United States to determine whether results from previous studies were general indicators or location specific in nature. To study the impacts of rain precipitation on hourly mean speeds and traffic volumes, hourly weather data and traffic sensor data were collected for two freeway segments in Jacksonville, Florida. The study investigated conditions such as wet versus dry (rain or no rain) and dry versus rain intensity (no rain or light, moderate, or heavy rain) for each segment. The results indicated that mean travel speeds decreased during rainfall events and speed reductions increased with increasing rain intensity. Reductions found for light rainfall events were within the range of previous studies; however, speed reductions during moderate to heavy rains varied widely. The results also indicated that the hour of the day was a factor in the degree of motorists’ speed reduction. Traffic volumes also declined during rainy conditions, with significant reductions during peak hours.

Assessing the Influence of Adverse Weather on Traffic Flow Characteristics Using a Driving Simulator and VISSIM

“…Many studies have focused on the impacts of weather on traffic flow characteristics such as average speed, traffic volume and road capacity [4][5][6][7][8][9][10]. Smith, Byrne, et al [4] investigated the impacts of different levels of rainfall intensity on freeway capacity and operation speed based on historical data.…”

A New Approach to Exploring the Relationship between Weather Phenomenon and Truck Traffic Volume in the Cold Region Highway Network

“…Conversely, during early evening hours and afternoon peak hours, significant amounts of reductions ranging from 17-76% are observed. In the study of Sando [2] for the Florida roads, it was observed that the average amount of decrease in speed due to rain event ranged from 1.5 to 3.5 mph for the control section of I-95, and it ranged from 1.8-2.5 mph for the control section of I-295. Hourly traffic volumes were also influenced by wet weather conditions.…”

“…In their model (see Equation 3), the independent variable Expected Volume Factor (EVF) contribution was significantly higher as compared to snow and cold while estimating the daily traffic volume. Roh et al [10,11,17] also used similar models (see Equations (1) and (2)) and it was found that the EDVF can explain about 78% of classified traffic variation. These studies along with other similar studies as shown in Table 1 fail to explain the relationship between the traffic variation, snowfall and temperature.…”

“…While the snow was lying on the ground, there was an average decrease of 10% in traffic activity during weekdays. Angel and Sando [2] found that mean travel speeds have been reduced during rainfall events on Florida highways including the fact that increasing the intensity of rain caused greater reductions in speed. Furthermore, the results indicate that the hour of the day is a factor affecting the reduction of speed and traffic volumes by motorists during rainy conditions.…”

“…Roh and Sharma [11] conducted a similar study on passenger car and truck traffic using the same study site with this research. They proposed another linear model written in Equation (2) to quantify the effect of snow and temperature on traffic volume changes.…”