Applying an improved calibration method in the safety evaluation framework for the open tolling system

Abstract

This study proposed an improved calibration method in the safety evaluation framework and analysed the safety effect of installing the open road tolling (ORT) system. Although the ORT system in South Korea has recently installed in many tollgate sections, it is impossible to collect statistically significant crash data. Therefore, the safety benefits were estimated and compared by (1) applying the general calibration way suggested in the Highway Safety Manual, (2) the recent calibration research from Florida and (3) the improved calibration method suggested in this study. In the result, safety improvement effect of ORT installation was 43% to 51%. Additionally, the calibration function using the quadratic model showed the best performance. This study is meaningful in that the safety effectiveness was estimated using the calibration method when the sample size was insufficient, and it utilises new functions to predict nonlinear relationships that are difficult to calibrate with simple linear relationships. © 2023 Hong Kong Society for Transportation Studies Limited.