A modular flooring system is disclosed which is designed to support heavy loads while providing stability and ground protection. The invention contemplates a modular mat having an integral main body with offset mounting and assembly flanges and a lattice interior. The mat is constructed from a unitary piece of high strength plastic. Each flange edge contains an outward radiused edge, while each non-flange edge contains an inward radiused edge. Each flange engages with a corresponding flange on an adjacent tile, allowing the outward radiused and inward radiused edges to properly mate. One or more metal cam locks located along the upper flange edges are secured into corresponding cam receptacles located along the lower flange edge. The mats may utilize optional top covers to prevent water and debris from entering the mats. The modular flooring system provides increased strength and stability and protection of the subsurface in heavy industrial applications.