Perception of low frequency vibrations by heavy vehicle drivers

A study was initiated to identify the levels and frequencies of heavy articulated vehicle body vibrations at which the drivers perceive the ride as uncomfortable. The study involved conducting a subjective assessment survey in which a panel of truck drivers were asked to rate the ride quality provided by a number of road sections with different surface roughness characteristics. The study's objective was achieved by correlating the mean panel ratings (MPRs) to road surface roughness contents in different one-third-octave bands of the roughness spectrum. The results showed that at 100 km/h, truck drivers object mainly to motions resulting from roughness excitations of the low frequency vibration modes of the truck body in the range 1.42 – 5.7 Hz. These results were validated by correlating MPRs with the levels of whole body vibrations measured on the driver's seat in a representative vehicle while traversing some test sections. MPRs were found to correlate well with the measured overall vibration total values and the likely comfort reactions to various magnitudes of overall vibration total values given by ISO 2631-1. The influence on MPRs of vehicle and driver related factors were also investigated and commented upon.