## 3 Field Experiment Design
### Field Experimental Procedure  
Before the beginning of the trial, the heavy-duty truck was equipped with a VBOX, and the conditions of all drivers and trucks were examined. The 11 heavy-duty truck drivers who volunteered to participate recorded their daily work data for one day in compliance with the Chinese Road Traffic Safety Law Implementation Regulations that driving time cannot exceed 8 h in a 24 h period. As a result, they performed their round-trip once a day.  
The VBOX system was installed in the test truck to collect speed, longitudinal acceleration, and lateral acceleration data. All field tests were carried out in good weather conditions. There was no crash or near-crash that occurred during the tests. The field tests were conducted from 8 May 2019 to 29 May 2019.  
All driving routes are shown in the Figure 2, indicated by orange lines. The location was in District Luhe, Nanjing. The sample intersection types are marked in different colors in Figure 2. All routes were round-trip.  
The trips in the field experiment were random and based on the business plan of the company. Due to individual independence, although a few intersections can be repeated on several trips, these intersections can be considered independently in this research. It is also important to take into consideration the different environments of the intersections, such as weather, traffic volume, and driver characteristics. In the experiments, the traffic-control types of intersection are divided into four types: Two-phase signalized intersection, Multiphase signalized intersection, Stop intersection, and Yield intersection. The experiment  
Figure 2: Field experiment routes and sample intersection types.  
collected data from 740 intersections in one month. Of these, 162 were two-phase signalized intersections, 177 were multiphase intersections, 208 were stop intersections, and the other 193 were yield intersections. In summary, this study includes 339 signalized intersections and 401 unsignalized intersections. There were 2 invalid intersections at stop intersections and 4 invalid intersections at yield intersections, making the total number of researched intersections 734. The intersection composition is shown in Table 1.  
As shown above, the largest difference in the number of intersections can be found between stop intersections and two-phase signalized intersections, with a difference of 46. The whole proportion of signalized intersections was 45.81%, and the proportion of unsignalized intersections was 54.19%. The trip environment was composed of urban roads and rural roads; the composition conforms to the actual situation. Among signalized intersections, the proportion of two-phase signalized intersections was 21.89% and multiphase signalized intersections was 23.92%. Similarly, for unsignalized intersections, the proportion of Stop intersections was 28.11% and Yield intersections was 26.08%. The proportions of the four intersection types were close to equal, for the purpose of this experiment. This means the analysis of the influence of intersection type on a driver's driving style was not biased due to the difference in sample size.