Evaluating time-reminder strategies before amber: common signal, green flashing and green countdown

The safety level of signalized intersection depends greatly on drivers' decision-making behaviors, which are significantly influenced by the time-reminder strategy before amber of the signal device. However, previous related studies are mainly based on the statistical results from the field data rather than explore the influence mechanism of the signal device on the signalized intersection's safety level. Therefore, this study aims to find out how these three typical signal devices with various time-reminder strategies, i.e., common signal device (CSD), green signal flashing device (GSFD), and green signal countdown device (GSCD), affect drivers' decision-making processes during the period from the end of the green phase to the onset of the red phase (i.e., G2R) and then evaluate their safety performance from the aspect of RLR violations. Firstly, an overall decision-making framework during G2R is presented to describe the driver-signal interaction and encloses four decision-making processes, which can be analyzed and modeled based on the field data collected from six signalized intersections in Changsha, China. Empirical analyses show that the time point of decision-making before amber under GSCD is the earliest and that under CSD is the latest, which can also be modeled and reproduced by back propagation neural network (BPNN). After that, five binary logistic regression models are developed to determine the safety effect during other various processes and results show that red-light-running (RLR) violations are not only dependent on the range of dilemma zones (DZ) but also substantially on stop and go decisions of those vehicles in DZ, both of which are the potential cause and direct factors to RLR violations and found to be significantly affected by the time-reminder strategy of the green signal device. Finally, although GSCD stimulates the drivers in DZ to choose to cross the intersection during amber, which produces a higher RLR risk compared with CSD and GSFD, the intersection with GSCD is verified to own the lowest RLR violations due to its greatly positive effect in cutting down the range of DZ.