We propose a new method for the economic evaluation of hybrid xed wireless/optical access networks. These networks are coste ective solutions in countries with a limited infrastructure. The evaluation of the cost function of such networks requires a detailed description of their spatial features that is usually not available and unsuitable for economic analysis. Our model captures the essential spatial characteristics of optical ring networks by representing its components as a family of random object generated by a spatial Poisson process. We give bounds on the cost of feeder rings and the exact cost function of distribution subnetworks as functional of the intensities of Poisson processes.