Accurately characterizing the propagation of RF signals in tunnels is important for rescue, safety, and military purposes. The material composition of the tunnel, the tunnel shape and size, obstructions, and tunnel bends are challenges facing the computational electromagnetic modeler. In the paper Modeling RF propagation in mines using Wireless InSite, we looked at how the material composition of the tunnel affects the propagation characteristics. In the paper Modeling RF propagation in mines using Wireless InSite, we looked at how the material composition of the tunnel affects the propagation characteristics. In this paper, we extend the analysis of tunnel propagation using RF modeling software, Wireless InSite, to tunnel diameter and tunnel shape. We extend the results reported by others by fitting the propagation characteristics to a Weibull distribution.