Develop a Methodology for Establishing Bump Detection Using Inertial Profile Measurements for Implementation with the Ride Specification: Summary Report

The Texas Department of Transportation (TxDOT) started implementing its new ride quality specification in 2002. This specification requires the use of inertial profilers in lieu of profilographs for quality assurance testing of surface smoothness on new construction and rehabilitation projects. The profilograph-based ride specification that it replaced includes criteria for both section¬wide and localized roughness. Although a method is currently used to evaluate localized roughness, its assessment, as well as that of section-wide roughness, is based on different criteria. The new ride specification identifies defects based on an allowable difference between the average measured profile and its moving average, and assesses section-wide roughness using the International Roughness Index (IRI). While both criteria are correlated to user perception of ride quality as measured by the Present Serviceability Index (PSI), PSI is not presently used to establish the need for corrections, nor are the improvements in PSI resulting from corrections evaluated or predicted in the new ride specification. A new equation was developed in Project 7 -490 I using data collected from two ride surveys conducted during the project. From analysis of profile data collected to verify the model, researchers on Project 7-490 I found the new equation to be more sensitive to the occurrence of localized roughness than IRI or the current ride equation. Thus, TxDOT initiated Project 0-4479 to investigate the application of the new equation for detecting defects in a smoothness specification. Its objectives are to: . determine methods for defining localized roughness characteristics that are objectionable to ride, and . establish how these characteristics can be measured in an effective way for construction quality control and assurance using inertial reference profile data.