Best Practices for Road Weather Management Version 2.0
Title:
The Impacts of Weather on Urban Freeway Traffic Flow Characteristics and Facility Capacity
Abstract:
This study describes how the authors quantified the impact of rain, snow, and various pavement surface conditions on freeway traffic flow for the metro freeway region around the Twin Cities. The research database includes four years of detector occupancy information from roughly 4,000 detectors and weather data over the same period from three Automated Surface Observing Systems (ASOS) at nearby airports and two years of pavement surface condition data from five Road Weather Information Systems (RWIS) sensors in close proximity to the freeway system. Our research classifies the rain and snow events by their intensity levels and identifies how changes in precipitation intensity impacts speed, headways, and capacity of roadways. Results indicate that severe rain and snow cause the most significant reductions in capacities and operating speeds. Heavy rains (greater than 0.25 inch/hour) and heavy snow (greater than 0.5 inch/hour) showed capacity reductions of 10 to 17 percent and 19 to 27 percent and speed reductions of 4 to 7 percent and 11 to 15 percent, respectively. Speed reductions due to heavy rain and snow were found to be significantly lower than those specified by the Highway Capacity Manual (HCM 2000).
Source(s):
2005 Mid-Continent Transportation Research Symposium; Iowa State University, Center for Transportation Research and Education. For an electronic copy of this resource, please direct your request to WeatherFeedback@dot.gov.
Date: 2005
Author:
Argarwal, Maze, Souleyrette
Keywords:
Snow
Pavement condition
Freeway management
Precipitation
Speed
Capacity
Precipitation
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