ILLISIM Program for End-Result Specification Development

Abstract

A new computer simulation program, called ILLISIM, is presented. ILLISIM allows the user to conduct a comprehensive assessment of agency and contractor risks over a wide variety of end-result specification (ERS) parameters. ILLISIM was created to assist the Illinois Department of Transportation (IDOT) in developing an ERS for asphalt pavement construction. The focus is on the use of ILLISIM to explore the possibility of using the nuclear density gauge as a basis for acceptance testing of as-constructed pavement density. Preliminary simulation results from ILLISIM suggest that it may be feasible to use the nuclear gauge for acceptance if stratified random sampling techniques and adequate test replications are used. However, this is true only if test bias is kept under control, for example, if a representative nuclear gauge-to-core correlation is maintained throughout the project. ILLISIM can be used to study the effects of changing device bias, which should be investigated in future work. The results also indicate that a larger sample size will be necessary to increase accuracy and minimize disputes when marginal quality levels are detected.