Evaluating the spatial and temporal distribution of beltway effects on housing prices using difference-in-differences methods

This study investigates the temporal and spatial distribution of the causal impacts of major beltway facilities on housing prices using quasi-experimental econometric approaches. Difference-in-differences methods are employed to quantify construction and anticipation effects and explore how impacts evolve and differ over space and time. The study particularly focuses on spatial variations and seeks to identify potentially heterogeneous effects in the inner and outer sides of a beltway. Two methods for control group selection are adopted to test the robustness of the estimated treatment effects. Using data from three major beltway facilities in the US, we find that impacts are nonlinear with distance from an interchange, with the maximum effect found between a 0.75 and 1.5-mile distance. In two of the studied beltway projects, properties outside the beltway experienced significant positive effects, while effects on properties inside the beltway were negative within the first 0.25 miles from an interchange and insignificant thereafter. We also find that effects during construction differ by project, while after the end of construction, prices typically increase and fully materialize after 6-8 years. This research makes a significant contribution to the very limited literature on the causal identification of highway impacts on surrounding properties as well as the small group of studies that have investigated the spatial extent and distribution of transportation-induced effects. The results can be used to inform stakeholders and planning decisions of future highway facilities.