The effect on commercial property of a major capacity expansion of a roadway facility in Austin, Texas, is examined by analyzing parcel-level real estate assessment data over an 18-year period (1982-1999). A land value model, an improvement or structure value model, and a total property value model were each estimated separately. Since total land values are fundamentally related to parcel acreages and improvement values are related to improvement size, parcel and improvement areas were related to appropriate access variables and structural variables. Empirical results suggest that improvement type, freeway proximity, parcel location at key network points (e.g., corner parcels), and timing of construction and completion play key roles in property valuation. The estimates of impacts should prove very helpful in comprehensive cost-benefit assessments of projects of this nature by public agencies and corridor property owners.