Since 1967, when Byrd, Tallamy, MacDonald and Lewis (BTMLI performed the original pavement maintenance study for the Illinois State Toll Highway Authority, there have been major changes in the characteristics of the highway, volume of traffic, and in the pavement composition itself. Several studies have provided Information to update the original maintenance and rehabilitation program, and the study reported here has created a continuity in this process. As the result of the comprehensive pavement evaluation by BTM L, data have been accumulated on current conditions of serviceability, slipperiness, surface defects, and deflection. These factors were considered individually as well as collectively to provide recommendations for improvements or rehabilitation. Current pavement condition was determined through visual and instrument surveys to provide present-serviceability-index factors and computations, traffic and axle-load analyses, and skid numbers for each of the three tollways in each direction. The visual pavement deficiencies-cracking, patching, faulting, and pumping-on rigid pavements were addressed by the visual survey. The instrument survey was concerned with the determination of roughness, skidding, and deflection data. Pavement condition was determined through the study of traffic volume, lane distribution, axle load, and the number of axle repetitions. Cumulative 18-kip single-axle loads were determined for the tollway. An Integral part of a pavement management system is an adequate data base. The evaluation performed by BTML compiles the data necessary to create a format adaptable for use in an effective pavement management system for the tollway. The pavement management framework is a manage· ment tool to aid consistency and optimization in the decision process. It is designed to expand decision-making capability as well as to provide necessary feedback on these decisions.

The Illinois Tollway consists of three toll highways--the Tri-State, East-West, and Northwest Tollways, as illustrated in Figure l. Together they total approximately 243 centerline miles, of which 104 miles have three traffic lanes in each direction. In addition to the main-line mileage, the Illinois Tollway consists of several access ramps, interchanges, and toll-collection facilities. The Illinois Tollway is a high-level system that serves motorists in the metropolitan Chicago area as well as throughout the state of Illinois. Segments of the tollway system serve more than 100 000 vehicles daily, which includes Interstate transport and localized commuter travel. Management decisions are made as a part of normal daily operations for an active highway system such as the Illinois Tollway. The pavement evaluation and rehabilitation criteria provided as a part of this study are intended as management tools to aid the decision maker. They are designed to improve the efficiency and consistency of the decisionmaking process.