ROAD SURFACE EVALUATION CONSIDERING SCOOTER RIDER SAFETY AND COMFORT

Abstract

 Traffic safety and comfort of two-wheeler users are the primary concerns of human-centered infrastructure design approach for daily commuters. Especially in developing countries including Nepal, the issue is crucial because of the predominance of two-wheelers such as motorcycles and motor scooters in urban traffic. The user comfort and safety are affected by the road surface roughness, thereby inducing the prominence in the maintenance of pavement surface corresponding to user satisfaction. The purpose of this study is to improve the maintenance criteria of pavement roughness considering the safety and comfort of motorized two-wheelers. For this purpose, we conduct a driving experiment with a motorized scooter on three types of road surfaces: dense graded asphalt pavement, block pavement, and dense graded asphalt pavement with manholes. In the experiment, we measured the vibration acceleration of both sprung and unsprung masses while riding on the surfaces to identify the excitation characteristics of the scooter interacting pavement roughness. As a result, three distinct peaks in terms of the frequency response which are associated with handlebar, steering component and axle resonance have been identified. The important finding obtained is that the surface wavelength range corresponding to the safety and comfort of two-wheelers differs from four-wheelers. This result suggests the incompatibility of traditional International Roughness Index for the evaluation of road surface from the viewpoint of scooter riding experience and implies the need for a particular maintenance criterion of pavement roughness considering the vehicle dynamics of two-wheelers considering the safety and comfort of users.