The long-term value proposition of transportation infrastructure investments can be significantly distorted if the short term effects of spatial externalities on land-use patterns, economic expansions, and migration patterns are not properly included in the analysis. Some of these effects occur over a short period of time and soon after the investment materializes, while others take longer and follow more steady patterns. In this paper, we develop a novel dynamical model of a primal society with constructs that are specifically geared toward transportation infrastructure expansions and investments. The model quantifies the impact of these expansions on some key performance indicators and on the overall utility and production capacity of the society. We argue that traditional analytical models that work on the premises of stationary behavior and a static response of society to changes in infrastructure do not correctly capture these effects. The land use patterns and spatial expansion computed from the model are validated against existing theory on land use. Preliminary results on how to use the model for value proposition analysis are also presented using simple case studies.