Improving IDOT's Pavement Condition Rating Process

The State of Illinois has been conducting Condition Rating Surveys (CRS) for nearly 30 years. The results of these condition surveys have become the primary vehicle for providing the executive and legislative offices with an assessment of the condition of the state's pavement network. The CRS has also become the cornerstone of the Illinois Department of Transportation (IDOT) pavement management system. The results are used extensively at the network level to determine budget share for the pavement improvement program and at the project level to determine priorities of specific pavement improvement proposals. The CRS initially involved a panel of four to five technical persons driving over each pavement section in the network to subjectively assign a numerical value ranging from 1.0 for a pavement in failed condition to 9.0 for a pavement in excellent condition. In 1989, several concerns prompted IDOT to investigate the feasibility of automating the collection of pavement condition data. These concerns included the safety of the expert panel; the reduction in staff and hiring restrictions being placed on the agency; and the total subjectivity of the existing assessment methodology. In 1994, IDOT adopted new automated technology to conduct the surveys. At the same time, IDOT hired a consultant to develop equations that could be used with identified predominant distresses to calculate a CRS value that falls within one-half point of the rating that would have been obtained through the manual on-site surveys. This paper documents the successful adoption of new technology, development of CRS models, and integration of the CRS models into the department's program development process. The changes brought about by automating the CRS process also increased the importance of properly identifying distress types and extent for each pavement section. As a result of this change, the department identified the need for additional training that could be used to supplement the annual training class and could provide immediate support to the CRS raters as they performed the condition assessment surveys. The paper also documents the development of the CD-based interactive training program that was developed for the department. The training program features an overview of the CRS process and individual distress identification.