Study of the Effectiveness of ITD Pavement Design Method
With limited funding, there is increased emphasis that current Idaho Transportation Department (ITD) flexible pavement design methods be the most cost effective. Current design methods range from empirical designs based on data from the 1950’s AASHTO Road Test, to methods developed by FHWA, methods developed by ITD/UI, and methods from other states. Based on information from surrounding states, there may be evidence that ITD’s traffic projections used to determine Equivalent Single Axle Loads (ESAL) in design are extremely conservative. The increased use of rockcap and other drainage features may not be given the appropriate credit in the existing design methods. Many existing roadways have performed beyond their calculated design lives, yet still perform adequately. ITD needs to evaluate existing design methodologies to determine if they are still applicable to current needs or if modifications can improve performance and reduce costs.