Modeling the Effects of Rainfall on Urban Freeway Free-Flow Speeds

Abstract:

This paper presents an investigation of the effects of rainfall with varying precipitation intensity at every millimeter interval on urban freeway free-flow speeds. The traffic data and corresponding weather information data from the Inner Ring in Shanghai for more than one year were used. Statistical and regression analysis were applied to investigate the effects quantitatively. There are three major contributions of this paper. Firstly, statistical analysis indicates that the rainfall does not significantly affect the speeds variability until the flow rate reaches to a certain level, such as 400veh/h/ln in this study. Secondly, the variation pattern of mean speeds at every millimeter interval of precipitation intensity was investigated. Thirdly, it is the first study to model the effects of precipitation intensity at every millimeter interval on free-flow speeds. Both piecewise linear model and natural logarithm model were used to model the effects of precipitation intensity. By comparing the two models, the piecewise linear model is proposed in this study.

• Periodical: Applied Mechanics and Materials (Volumes 178-181)
• Pages: 2577-2585
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.178-181.2577
• Online since: May 2012
• Authors: Li Juan Shi, Yang Cheng, Dong Xiu Ou, Xiao Hong Chen
• Keywords: Effects of Rainfall, Free-Flow Speeds, Natural Logarithm Model, Piecewise Linear Model, Statistical Analysis, Urban Freeway

References

[1] Highway Capacity Manual. TRB, National Research Council, Washington, D.C., 2000.

[2] Ibrahim, A. T., and F. L. Hall. Effect of Adverse Weather Conditions on Speed-Flow-Occupancy Relationships. In Transportation Research Record 1457, TRB, National Research Council, Washington, D.C., 1994, p.184 –191.

[3] May, A.D.. Capacity and Level of Service for Freeway Systems, Third Interim Report, Phase C, Tasks C1 through C10, NCHRP, Washington, D.C. June 12, 1998.

[4] Billot, R., N. E. E. Faouzi, and F. D. Vuyst , Multilevel Assessment of the Impact of Rain on Drivers' Behavior, Standardized Methodology and Empirical Analysis, Transportation Research Record 2107, TRB, Washington, D.C., 2009, p.134–142.

DOI: 10.3141/2107-14

[5] M. Kyte, Z. Khatib, P. Shannon, and F. Kitchener. Effect of Weather on Free-Flow Speed. In Transportation Research Record 1776, TRB, National Research Council, Washington, D.C., 2001, p.60 –68.

DOI: 10.3141/1776-08

[6] Federal Highway Administration. Empirical Studies on Traffic Flow in Inclement Weather. FHWA-HOP-07-073, 2006.

[7] Brilon W., and M. Ponzlet. Variability of Speed-Flow Relationships on German Autobahns. Transportation Research Record 1555, TRB, National Research Council, Washington, D.C., 1996, p.91–98.

DOI: 10.1177/0361198196155500112

[8] Agarwal M., T. H. Maze, and R. Souleyrette. Impacts of Weather on Urban Freeway Traffic Flow Characteristics and Facility Capacity. Proceedings of the 2005 Mid-Continent Transportation Research Symposium, Ames, Iowa, US, 2005.

[9] Nookala, L.S., Weather Impact on Traffic Conditions and Travel Time Prediction. Master Degree Dissertation, University of Minnesota Duluth, US, 2006.

[10] Chin, S. M., O. Franzese, and D. L. Greene. Temporary Losses of Highway Capacity and Impacts on Performance: Phase 2 . ORNL/TM-2004/209, Oak Ridge National Laboratory, US, 2006.

[11] L. Shi, Y. Cheng, J. Jin, B. Ran, and X. Chen. Effects of Rainfall and Environmental Factors on Characteristics of Traffic Flow Fundamental Diagram on Urban Freeway, Transportation Research Board，90th Annual Meeting，January 23-27, 2010，Washington, D.C..