Real Time Surface Defect Measurement From Road Profile

Abstract

The Texas Department of Transportation (TxDOT) annually collects profile data over the state maintained highway network and uses the profile data to determine the ride quality based on a serviceability index (SI) and the International Roughness Index (IRI). The equation used at present to obtain the SI from the profile data is based on ride measurements from an old rating session in the 1960s. Several changes have taken place over the years that required re-evaluation of the ride equation, led to a TxDOT funded research in 2000 to evaluate the adequacy of the current equation. During this study, a new ride equation or NSI was developed and found to correlate much better to how the travelling public rates pavements than the old ride equation IRI. This thesis is aimed at developing a real-time multi-threaded embedded module and program that can be used with a portable profiler for measuring NSI. It also includes investigations on the effectiveness of the new ride equation from recent profile and resulting IRI measurements. Specifically, this study investigates the use of a real-time system to calculate the NSI (New Serviceability Index), the index generated by the new ride equation.This thesis focuses on collecting simulated profile data for a stretch of the road and calculating the roughness index for each section. The minimum size of the sections is 52.8ft or 0.01miles. Simulations are generated based on the profile data generated by the laser and accelerometer readings at the profiler. These profile simulations are processed in real-time, as soon as the data for each user-specified section length is available, using the new ride equation. This calculates the NSI for each section and the resulting NSI values are displayed. Investigations are also included comparing the NSI to IRI for profile obtained from a number of different pavement types measured during a recently completed TXDOT research project.