Concrete overlay pavements are expected to have reduced crack widths when the concrete mixture contains fibers. However, it is still unknown how much the crack widths can be reduced due to the fiber-bridging effect in these fiber- reinforced concrete (FRC) overlays. A previously constructed full-scale thin FRC overlay was investigated for this study. This full-scale experiment has only been subjected to environmental loading for 5 years. Field observation results showed that crack width increased as the cracked-joint spacing increased for the same FRC material. This study investigates determining the average crack width and debonding length through a numerical study and is validated by the field project. A two-dimensional finite element model was developed to verify fiber-bridging effect and the amount of layered-interface debonding in FRC overlay structure. A cohesive behavior was defined for both the joint location and the underlying interface between the FRC and existing pavement. The vertical deflection, crack widths, and debonding length were studied based on the modeling inputs of varying fracture energy and elastic modulus of the FRC overlay, as well as varying interface tensile bond strength and elastic foundation stiffness. The developed model matches the measured crack widths from the experimental field project. Additional data from the numerical study indicate that crack opening widths, vertical joint deflection, and debonding length all decreased as the fracture energy and tensile bond were increased.