关键词: 城市交通, 自然驾驶实验, 驾驶心理负荷, 心率变异性, 螺旋桥

Abstract:

To analyze drivers' mental load and the influencing factors when driving on the helical ramps and helical bridges, field driving tests using real passenger cars were conducted on four interchanges in a mountain city. The driver's ECG signals under the natural driving habits were collected by onboard instruments. Based on this naturalistic driving data, the relationship between heart rate amplitude, the RMSSD index overall distribution, and the ramp radius and slope were analyzed. The results indicated that the driving environment and horizontal curvature of the ramp, as well as the on-ramps junction and diversion, are the main factors of the mental load. The following, overtaking and meeting in the driving process all increase the driver's mental load. The driver's nervousness is higher when they are driving on uphill ramps than that on the downhill ramps. There is a strong negative correlation between the ramp radius and heart rate variability. Moreover, the unskilled driver is the most sensitive to the change of the ramp radius. There are two different correlations between ramp gradient and the heart rate variability: for unskilled drivers, the RMSSD increases linearly as the slope increases, while for the general and skilled drivers, their RMSSD profiles have a trend of high in the middle and low on both sides.

Key words: urban traffic, naturalistic driving test, driving mental load, heart rate variability, helical bridge