# Eye-Tracking Investigation of the Train Driver's: A Case Study
## 2 Materials and Methods
### Eye-Tracking Technology  
Investigation of human factors utilizing the user testing method is a viable approach for exploring the level of interaction between humans and machines. To maximize the efficacy of usability testing, a representative sample of the targeted user group should be chosen and the data collection techniques must be capable of capturing the demands associated with the activities performed. Eye-tracking technology provides a unique opportunity for user testing as it is capable of measuring the perception and behavior of the tested subject while they are completing the assigned tasks. The usefulness of eye tracking in transport systems is evident, as it has been employed for various measurements in both real and simulated environments and is especially advantageous for the analysis of human behavior in aviation and vehicle driving. The application of eye-tracking technology was utilized to analyze the train driver's behavior with great accuracy while in operation. The SMI ETG 2W head-mounted eye-tracking glasses with software iViewETG version 2.8 were selected to procure raw data. This device was specifically designed to capture the visual conduct of the subject in real-time scenarios. Equipped with three high-speed cameras, two infrared cameras were used to record the subject's pupils' movement and position in both eyes, while the third high  
Figure 4: Track section Zilina–Püchov with railway stops and train stations. definition scene camera with a resolution 1280 \(\times\) 960 p @24 fps captured the surrounding environment. Additionally, a smartphone was connected to the glasses for data recording purposes. The SMI ETG 2W provides eye tracking with a sampling frequency of 60 Hz throughout the field of view and guarantees precise data with a tracking range of 80\({}^{\circ}\) horizontal, 60\({}^{\circ}\) vertical, and a gaze tracking accuracy of 0.5\({}^{\circ}\) over all distances [45]. The SMI BeGaze software 3.7.59 (produced by SensoMotoric Instruments (SMI), Teltow, Germany) was employed to conduct an in-depth analysis of the raw data collected by the SMI ETG 2W. This comprehensive application provided a range of analytical functionalities, including Scan Path, which illustrated the map of the driver's gaze fixations and the order in which they occurred. The most beneficial analytical tool for our research, included in the BeGaze software, was the AOI (Areas of Interest) analysis. In this analysis, user-defined metrics were extracted from the pre-defined regions in the visual stimulus. To identify the areas of train control and operation, the AOI editor was used to designate the main AOIs in the train cabin. As a result, thirteen AOIs (panels) were identified (see Figure 5). The Areas of Interest (AOI) displayed in the figure are numerically coded from A to M, each representing a distinct aspect of the train's operation:  
* A stands for the view of the external environment, encompassing front, right, and left windows. * B stands for the left and right rear-view mirrors. * C denotes railway signals. * D is indicative of the actual speed, as shown in Panel D.
* E is the main train operating window. * F corresponds to the cab signaling and the train protection system Mirel
* G is for the brake system pressure. * H refer to the set of train driving controllers. * I is the automatic train speed controller. * J is the main train controller, controlling both acceleration and braking. * K is the timetable sheet. * L is for notes pertaining to the section, such as speed restrictions. * M is the signaling of safety closure of the train doors. Observe that the cab display of the European Train Control System (ETCS) is depicted in Figure 5, with the black window located above region K. Nonetheless, since the ETCS is not in use, it has been deactivated. In order to acquire pertinent information from eye-tracking recordings, the fixation-to-fixation coding technique was utilized.