Driver’s physiological responses to negotiating urbanization highways of varying complexity

In the progress of urbanization, serious crashes on curved sections of urbanization highway are a significant problem. The main reason is that urbanization highways have an impact on drivers’ physiological status. In this paper, three road simulation scenarios were implemented in a driving simulator: ‘non-urbanization highway’, ‘semi-urbanization highway’ and ‘urbanization highway’. Drivers’ physiological features were studied by observing their heart rate growth rates. The results demonstrate that heart rate growth rate was significantly affected by the degree of urbanization of the highway. On curved segments of urbanization highway, heart rate growth rate changes and vehicle speed fluctuations were significant. Moreover, heart rate growth rates in the uplink direction of curves were higher than those in the downlink direction. Speed and heart rate growth rate were highly correlated. Within the same degree of urbanization highway, drivers’ heart rate growth rates first decreased and then increased with increasing speed. A correlation model of the degree of urbanization, vehicle speed and heart rate growth rates is proposed and used to derive safety thresholds based on heart rate growth rate. The safety thresholds of heart rate growth rate were 7.6%, 22.0% and 37.0% at ‘good’, ‘fair’ and ‘poor’ levels, respectively. The main results provide a basis for identifying dangerous road sections and improving the driving comfort and safety of urbanization highways.