Long-term infrastructure leases are complex deals with serious implications for drivers, businesses, communities and a state's economic future. But the money usually grabs the headlines-billion-dollar headlines in the cases of the Indiana and Chicago leases. Behind those dollar signs are assumptions about the asset's worth, expected investment returns and ability to generate new revenue, and how the monies will be spent. Both a state and a private operator use these assumptions to decide whether the deal is worth it.