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 JTTs  Vol.6 No.5 , October 2016
Estimating Crash Rate of Freeway Segments Using Simultaneous Equation Model
Abstract: This study develops crash rate prediction models based on the premise that crash frequencies observed from adjacent paired non-weaving and weaving freeway segments are spatially correlated and therefore requires a simultaneous equation modeling approach. Simultaneous equation models for paired freeway non-weaving segments and weaving segments along with combined three freeway segments upstream and downstream were developed to investigate the relationship of crash rate with freeway characteristics. The endogenous variables have significant coefficients which indicate that unobserved variables exist on these contiguous segments, resulting in different crash rates. AADT is a variable that can show the interaction between the traffic and crashes on these contiguous segments. The results corroborate such an interaction. By comparing the simultaneous equation model and the multiple linear regression model, it is shown that more model parameters in the simultaneous models are significant than those from linear regression model. This demonstrates the existence of the correlation between the interchange and between-interchange segments. It is crucial that some variables like segment length can be identified significant in the simultaneous model, which provides a way to quantify the safety impact of freeway development.
Cite this paper: Ramos, A. , Teng, H. and Fu, Y. (2016) Estimating Crash Rate of Freeway Segments Using Simultaneous Equation Model. Journal of Transportation Technologies, 6, 327-338. doi: 10.4236/jtts.2016.65029.
References

[1]   Park, B.-J., Fitzpatrick, K. and Lord, D. (2009) Evaluating the Effects of Freeway Design Elements on Safety. Transportation Research Board, Washington DC.

[2]   Golob, T.F., Recker, W.W. and Alvarez, V.M. (2004) Safety Aspects of Freeway Weaving Sections. Transportation Research Part A, 38, 35-51.
http://dx.doi.org/10.1016/j.tra.2003.08.001

[3]   Geedipally, S.R., Bonneson, J.A., Pratt, M.P. and Lord, D. (2012) Safety Prediction Methodology and Analysis Tool for Frewways and Interchanges, NCHRP 17-45. Transportation Research Board, Washington DC.

[4]   Haleem, K., Gan, A. and Lu, J. (2013) Using Multivariate Adaptive Regression Splines (MARS) to Develop Crash Modification Factors for Urban Freeway Interchange Influence Areas. Accident Analysis and Prevention, 55, 12-21.

[5]   Teng, H., Mulokozi, E., Ramos, A. and Gibby, R. (2013) Evaluation of Geometric Design Needs of Freeway Systems Based on Crash and Geometric Data. TRB 93rd Annual Meeting for Transportation Research Record, 12-16 January 2014, Washington DC.

[6]   Zhang, Y., Li, Z., Liu, P. and Zha, L. (2011) Exploring Contribution Factors to Crash Injury Severity at Freeway Diverge Areas Using Ordered Probit Model. Procedia Engineering, 21, 178-185.

[7]   O’Cinneide, D. (1998) The Relationship between Geometric Design Standards and Safety. Transportation Research Board Record, 44:1-7.

[8]   Pilko, P., Bared, J.G., Edara, P.K. and Kim, T. (2007) Safety Assessment of Interchange Spacing on Urban Freeways. U.S. Department of Transportation, Federal Highway Administration, MCLean, VA.

[9]   Wackerly, D.D., Mendenhall III, W. and Scheaffer, R.L. (2008) Mathematical Statistics with Applications. Seventh Edition, Brooks/Cole, Belmont, CA.

[10]   Greene, W.H. (2008) Econometric Analysis. 6th Edition, Pearson Prentice Hall, Upper Saddle River.

[11]   Washington, S.P., Karlaftis, M.G. and Mannering, F.L. (2011) Statistical and Econometric Methods for Transportation Data Analysis. Second Edition, Chapman & Hall/CRC, Boca Raton, FL.

[12]   Zellner, A. and Theil, H. (1962) Three-Stage Least Squares: Simultaneous Estimation of Simultaneous Equations. Econometrica, 30, 54-78.
http://dx.doi.org/10.2307/1911287

[13]   Henningsen, A. and Hamann, J.D. (2007) systemfit: A Package for Estimating Systems of Simultaneous Equations in R. Journal of Statistical Software, 23, 1-40.
http://dx.doi.org/10.18637/jss.v023.i04

[14]   (2010) Highway Safety Manual. The American Association of State Highway and Transportation Officials, Washington DC.

 
 
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