Study Details

Study Title: The Group Least Absolute Shrinkage and Selection Operator "GLASSO" Technique: Application in Variable Selection and Crash Prediction at Unsignalized Intersections

Authors: Haleem and Abdel-Aty

Publication Date: JUN, 2010

Abstract: In this paper, we propose a new promising machine learning technique to select important explanatory covariates, as well as to improve crash prediction; the group least absolute shrinkage and selection operator (GLASSO) technique. GLASSO"s main strength lies in its ability to deal with datasets having relatively large number of categorical variables, which is the case in this study. Identifying the significant factors affecting safety of unsignalized intersections was also an essential objective. Two applications of GLASSO were investigated; application for variable screening before fitting the traditional negative binomial (NB) model, as well as before fitting another promising data mining technique (the multivariate adaptive regression splines "MARS"). Extensive data collected at 2475 unsignalized intersections were used. For fitting the NB models, the backward deletion and the random forest techniques were separately used as variables 11 screening, and their prediction performance was compared to that from GLASSO. All the three methods resulted in almost similar predictions. For GLASSO's second application with MARS, the model fitting relatively outperformed that from the random forest technique with MARS, with similar prediction performance. Due to its outstanding performance with categorical variables, as well as its simplicity, GLASSO is recommended as a promising variable selection technique. Significant predictors affecting total crashes at unsignalized intersections were traffic volume on the major road, the upstream and downstream distances to the nearest signalized intersection, median type on major and minor approaches, and type of land use. Resembling previous studies, the volume of traffic was the most important predictor.

Study Citation: Haleem, K. and Abdel-Aty, M. "The Group Least Absolute Shrinkage and Selection Operator "GLASSO" Technique: Application in Variable Selection and Crash Prediction at Unsignalized Intersections." Presented at the 90th Annual Meeting of the Transportation Research Board, Washington, D.C., (2011).


CMFs Associated With This Study

Category: Access management

Countermeasure: Add markings to the major approach of unsignalized 3-leg intersection to serve as a median

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
0.7 30 3 Stars All All Not Specified All

Countermeasure: Add Two-Way-Left-Turn-Lane (TWLTL) to the major approach of an unsignalized 3-leg intersection

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
0.69 31 3 Stars All All Not Specified All

Countermeasure: Add Two-Way-Left-Turn-Lane (TWLTL) to the major approach of an unsignalized 4-leg intersection

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
0.66 34 3 Stars All All Not Specified All

Countermeasure: Convert a 3-leg unsignalized intersection at a driveway to a regular 3-leg unsignalized intersection

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
1.41 -41 3 Stars All All Not Specified All

Countermeasure: Convert an open median on the major approach to unsignalized 3-leg intersection to a closed median

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
1.02 -2 3 Stars All All Not Specified All

Countermeasure: Convert an open median to a mixed median on the major approach to a 3-leg unsignalized intersection

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
0.95 5 3 Stars All All Not Specified All

Countermeasure: Convert an open median to an undivided median on the major approach to an unsignalized 3-leg intersection

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
0.85 15 3 Stars All All Not Specified All

Countermeasure: Convert the open median on the major approach of an unsignalized 3-leg intersection to a directional median

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
0.86 14 3 Stars All All Not Specified All

Countermeasure: Install median on the minor approach of an unsignalized 3-leg intersection

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
0.82 18 3 Stars All All Not Specified All

Category:Intersection geometry

Countermeasure: Convert a 3-leg unsignalized intersection at a driveway to a 3-leg unsignalized intersection at a ramp junction

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
2.29 -129 3 Stars All All Not Specified All

Countermeasure: Convert a 4-leg unsignalized intersection at driveways to a regular 4-leg unsignalized intersection

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
1.11 -11 3 Stars All All Not Specified All

Countermeasure: Install one left-turn lane on both major road directions

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
1.36 -36 3 Stars All All Not Specified All

Countermeasure: Install one left-turn lane on the minor approach of an unsignalized 3-leg intersection

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
0.75 25 3 Stars All All Not Specified All

Countermeasure: Installation of left-turn lanes on both major road approaches

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
0.73 27 3 Stars All All Not Specified All

Countermeasure: Provide a right-turn lane on one major-road approach

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
0.83 17 3 Stars All All Not Specified All

Category:Intersection traffic control

Countermeasure: Install a stop sign on both minor approaches of an unsignalized intersection

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
0.78 22 3 Stars All All Not Specified All

Category:Pedestrians

Countermeasure: Install crosswalk on one minor approach

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
0.35 65 3 Stars All All Not Specified All

Category:Shoulder treatments

Countermeasure: Change right shoulder width from X to Y

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
CMF Equation CRF Equation 3 Stars All All Not Specified All