Research on Comfort and Safety Threshold of Pavement Roughness

Abstract

Pavement roughness, which may cause vehicle vibrations and driving instability and even cause loss of control, is the main cause of unsafe and uncomfortable driving. In most countries, the international roughness index (IRI) is used to measure pavement roughness. Driving comfort and safety are currently evaluated with an empirical method of expert scoring, and reliable experimental measurements are not created. Based on previous work, which included evaluation of driving comfort and safety (driving workload) according to physiological and psychological indexes, as well as thresholds of driving comfort and safety, this paper determines the mathematical relationship between IRI and driving workload with experimental data of real vehicles to study the threshold of IRI for driving comfort and safety. Experimental data, including physiological and psychological indexes, driving speed, and IRI, of 12 car drivers and 12 truck drivers driving at a speed of 60 km/h were collected on a road with high alignment elements that had no impact on driving workload in northwest China. The mathematical relationships between IRI and driving workload of car drivers and truck drivers were determined, and thresholds of IRI on road segments at various risk levels for driving comfort and safety were obtained. The results show that standard IRI values for pavement maintenance in China are beyond the comfort and safety thresholds for both car drivers and truck drivers. Methods and conclusions in this paper could provide theoretical and technical support for the improvement of pavement service.