Methodology for quantifying whole-body vibration experienced by bicyclists

Abstract

This paper presents an examination of the fundamental relationships between rumble strip dimensions, bicyclists' perceptions of ride comfort and the controllability of a bicycle. These relationships were developed using data gathered during a study, the Bicycle-Tolerable Shoulder Rumble Strips project, conducted at the Pennsylvania Transportation Institute and by gathering supplemental data to evaluate the ride quality of bicycles. These relationships will help highway agencies develop better rumble strips policies that consider the entire range of highway users. The research methodology consisted of 5 primary tasks. First, a method was developed for quantifying whole-body vibration experienced by bicyclists. Second, the relationships between whole-body vibration, bicyclists' perceptions of comfort and the controllability of a bicycle were assessed. Third, a regression model was developed to explain how whole-body vibration varies with the dimensions of rumble strips, the characteristics of the bicycle and the characteristics of the bicyclist. Fourth, by modelling whole-body vibration and by understanding the relationship between whole-body vibration, comfort and control, the conditions that cause bicyclists to experience the highest levels of discomfort and control problems while traversing rumble strips were identified. Fifth, the ride characteristics of the bicycles were assessed using vehicle ride models. It is concluded that bicyclists' concerns of traversing rumble strips are warranted. Bicyclists can experience extremely high levels of whole-body vibration while traversing rumble strips and the analysis suggests the relationship between whole-body vibration and bicyclists' perceptions of comfort is linear; as vibration increases comfort decreases. The analysis also indicates there is no clear relationship between whole-body vibration and the controllability of a bicycle. It is also concluded that whole body vibration increases with unit increases in groove depth and tyre pressure, while whole-body vibration decreases with unit increases in groove spacing. In addition, a bicyclist experiences the highest levels of whole-body vibration while traversing rumble strip configurations at a speed of approximately 20 km/h. Finally, bicycles without active suspensions exhibit poor vibrational characteristics because the oscillation centres of the bicycles are not located near the optimum location for a good ride.