Related Experiment Video
Updated: Feb 26, 2026

Evaluation of an Exclusive Spur Dike U-Turn Design with Radar-Collected Data and Simulation
Published on: February 1, 2020
A Heckman selection model for the safety analysis of signalized intersections
Xuecai Xu1,2, S C Wong3, Feng Zhu2
1School of Civil Engineering and Mechanics, Huazhong University of Science and Technology, Wuhan, China.
Purpose:
The objective of this paper is to provide a new method for estimating crash rate and severity simultaneously.
Methods:
This study explores a Heckman selection model of the crash rate and severity simultaneously at different levels and a two-step procedure is used to investigate the crash rate and severity levels. The first step uses a probit regression model to determine the sample selection process, and the second step develops a multiple regression model to simultaneously evaluate the crash rate and severity for slight injury/kill or serious injury (KSI), respectively. The model uses 555 observations from 262 signalized intersections in the Hong Kong metropolitan area, integrated with information on the traffic flow, geometric road design, road environment, traffic control and any crashes that occurred during two years.
Results:
The results of the proposed two-step Heckman selection model illustrate the necessity of different crash rates for different crash severity levels.
Conclusions:
A comparison with the existing approaches suggests that the Heckman selection model offers an efficient and convenient alternative method for evaluating the safety performance at signalized intersections.
Related Concept Videos
Routh-Hurwitz Criterion II
The first scenario occurs when a singular zero appears in the first column of the Routh table. This situation creates a division by zero issues. To resolve this, a small positive or negative number, denoted as epsilon (∈), is substituted for the zero. The stability analysis proceeds by assuming a sign for ∈. If ∈ is positive, any sign change in the first...
Hazard Rate
Survey Safety
Routh-Hurwitz Criterion I
To apply the Routh-Hurwitz criterion, a Routh table is constructed. The table's rows are labeled with powers of the complex frequency variable s, starting from the...
Assumptions of Survival Analysis
Sign Test for Matched Pairs
To conduct the sign test, we first calculate the differences in...

