In recent years researchers have considered a variety of regional models relating to infrastructure productivity. These models are often based upon overly simple econometric specifications and are typically formulated as if spatial interactions are absent. In this paper, we try to account for some of these shortcomings. We do this by considering spatial lags of certain independent variables, as well as of the dependent variable. We also consider spatial correlation of the error terms, general patterns of heteroscedasticity and of time series autocorrelation, and systems problems.