This document describes a reduced-scale model that was created to study surge characteristics on a transmission line system. The model includes two tower models and a gantry model to represent the portion of transmission line coming into a substation. Experiments were conducted by injecting a steep current wave into the top of the first tower model. Voltages were measured at various points with and without a back-flashover occurring. The results provide insight into how lightning-induced surges propagate and the voltage waveforms that appear at the tower and gantry sections.