A modular pavement slab comprises a body, a strain sensor array, and a sensor processor. The body includes a top surface, a bottom surface, and four side surfaces. The modular pavement slab is configured to be coupled to at least one other modular pavement slab via connectors along at least one of the side surfaces. The strain sensor array is retained within the body and is configured to detect a plurality of strains on the body resulting from vehicular traffic across the top surface of the body. The sensor processor is in communication with the strain sensor array. The sensor processor is configured to communicate input signals to the strain sensor array, receive output signals from the strain sensor array, and determine a plurality of time-varying strain values, each strain value indicating a strain experienced over time by a successive one of a plurality of regions of the body.