Characterising pavement roughness at non-uniform speeds using connected vehicles

ABSTRACT

Methods of pavement roughness characterisations using connected vehicles are poised to scale beyond the frequency, span and affordability of existing methods that require specially instrumented vehicles and skilled technicians. However, speed variability and differences in suspension behaviour require segmentation of the connected vehicle data to achieve some level of desired precision and accuracy with relatively few measurements. This study evaluates the reliability of a Road Impact Factor (RIF) transform under stop-and-go conditions. A RIF-transform converts inertial signals from on-board accelerometers and speed sensors to roughness indices (RIF-indices), in real-time. The case studies collected data from 18 different buses during their normal operation in a small urban city. Within 30 measurements, the RIF-indices distributed normally with an average margin-of-error below 6%. This result indicates that a large number of measurements will provide a reliable estimate of the average roughness experienced. Statistical t-tests distinguished the relatively small differences in average roughness levels among the roadway segments evaluated. In conclusion, when averaging roughness measurements from the same type of vehicle moving at non-uniform speeds, the RIF-transform will provide ever-increasing precision and accuracy as the traversal volume increases.

KEYWORDS:

• Connected vehicle
• inertial profiler
• intelligent transportation systems
• pavement management
• probe vehicles
• ride quality
• roughness index
• suspension systems

Acknowledgements

A grant from the National Center for Transit Research (NCTR) and the Small Urban and Rural Transit Center (SURTC) of the Upper Great Plains Transportation Institute, North Dakota State University supported this research. The authors also express their sincere appreciation to Julie Bommelman (Transit Administrator of the City of Fargo), James Gilmour (Planning Director of the City of Fargo) and Gregg Schildberger (Senior Transit Planner for the City of Fargo) for their support in accessing the buses for roughness measurements.

Additional information

Funding

The University Transportation Center, a programme of the United States Department of Transportation, sponsored this research through the National Center for Transportation Research at the University of South Florida, under sub-agreement #2117–9060-02-A.