Investigation on Driving Comfort of Passenger Cars on Mountain Roads Based on Naturalistic Driving

Naturalistic driving tests were conducted using real vehicles on six roads to study the level of driving comfort on two-lane mountainroads and the key influencing factors. In the tests, acceleration data of passenger cars were collected; after filtered using Matlab software, the peak value of each waveform of the measured data was extracted to obtain the cumulative frequency profiles of peak accelerations of different axes, as well as the characteristic percentile values and the root mean square (RMS) values. The results show that the longitudinal acceleration rate ax on two-lane highways is only half the deceleration rate ab in braking. The locations where the acceleration and deceleration cause occupants discomfort account for 6% of the total test points at the most. The ratio of road sections where occupants feel discomfort in lateral direction ranges from 7% to 10% of the total trip; Among all the axial accelerations, lateral acceleration ay, braking acceleration ab,the longitudinal acceleration ax and vertical acceleration az make the greatest part of contribution to the discomfort.