Evaluation of New Brunswick pavement overlay design
University of New Brunswick
The method currently used by the New Brunswick Department of Transportation (NBDOT) to design overlay pavement structures is based solely on pavement deflections. Two methods are used in this study for comparison: the Ontario OPAC design and the Asphalt Institute overlay model. The OPAC design estimated more conservative overlay thickness than the current NBDOT method. The extra thickness results from the OPAC use of a maximum value of 11,500 psi for subgrade modulus; although New Brunswick has much stronger subgrade materials in many areas. The Asphalt Institute is similar to the NBDOT method. This model normally gave greater overlay thicknesses than the NBDOT method since traffic intensity was considered by the Asphalt Institute method.