Tolls have been used as a major source of transportation finance for more than 50 years and with recent innovations in all-electronic tolling technology, tolling interstates is being considered a viable alternative transportation finance approach. A transportation financing approach being considered by State Departments of Transportation (DOTs) involves the collection of tolls on existing interstate highways on which tolls are not presently collected; however, there are challenges associated with estimating demand changes on these roadways. Central to this paper is a case study that focuses on the formulation and preliminary evaluation of a toll based financing approach potentially suitable for consideration along a segment of Interstate 93 in Boston where tolls are not currently charged. The literature and previous work show that elasticity based methods have been used and are an appropriate first step for estimating transportation demand changes. In this case study, the evaluation includes two different analysis approaches of the expected change in demand: one that takes into account the cost of congestion and one that does not. The results in this paper will guide transportation planners and analysts interested in estimating expected demand changes due to the placement of tolls on interstates not currently tolled. Moreover, these results will enhance our knowledge base concerning the analytical challenges associated with estimating demand changes on roadways that are not currently tolled.