The purpose of this study is to extend the use of ground-penetrating radar (GPR) methodology toward a more reliable and accurate interpretation of pavement conditions. With the electromagnetic Green's function for a layered system with a horizontal electric dipole, the GPR scan can be simulated over a wide range of pavement profiles. Examples are provided for GPR simulation on a three-layer pavement system. With forward model, the best match of the GPR scan in terms of the full waveform can be recovered within thousands of simulations via the optimization routine, where the in situ layer parameters associated with the measurement are found to be equal to the simulation inputs. The accuracy of the interpreted layer thickness from the proposed scheme is verified by ground truth, with average error around 2.3% compared with 7.5% average error for the traditional method. In addition, the proposed scheme, unlike the traditional method, allows an evaluation of the relevant pavement properties with no prior assumptions or subjective image adjustments.