01334623

Component

This paper presents an investigation of the effects of rainfall and road environmental factors on traffic flow characteristics of urban freeway. The traffic data and corresponding Road Weather Information System (RWIS) data for a road segment of I-894/US45 in Milwaukee for three years were used in this study. Effects of rainfall and environmental factors on the free-flow speed of urban freeway were quantified and determined using regression analysis. Statistical analysis of the experimental results indicates that when considering the impact of RWIS parameters on traffic state variables (speed, flow, occupancy) in general, their correlations are weak. However, if the characteristic parameters (e.g., free-flow speed and capacity) of traffic flow are considered, some RWIS parameters such as level of rainfalls, illumination (daytime or nighttime), pavement surface condition and temperature, have statistically significant impact. Meanwhile, visibility and wind speed (lower than 21 mi/hr) are found to have insignificant effect on free-flow speed, which is different from some previous studies. Third, the effects of rainfall and environmental factors on free-flow speed for urban freeway in this study are less significant, which is different from the results obtained from previous rural freeway studies.

01329018

11-3345

English

17p

2011

Transportation Research Board 90th Annual Meeting

DVD

Figures (10) ; References (10) ; Tables (4)

Environmental impacts; Free flow speeds; Highway operations; Lighting; Rainfall; Road weather information systems; Statistical analysis; Traffic data; Traffic flow; Traffic safety; Traffic speed; Visibility; Weather conditions

Milwaukee (Wisconsin)

Highways; Operations and Traffic Management; Planning and Forecasting; I72: Traffic and Transport Planning

Transportation Research Board Annual Meeting 2011 Paper #11-3345

TRIS, TRB

Feb 17 2011 6:29PM