AASHTO has tasked Mercator Advisors with a series of special research projects related to federal funding and financing issues. One such project involves developing and operating a sophisticated financial model of the federal Highway Trust Fund (HTF). This model estimates the impact on future-year Highway Account and Mass Transit Account balances resulting from various assumptions concerning revenue and spending patterns. Drawing upon our knowledge of federal budgetary practices, Mercator has designed the model to quickly assess the impact of the latest revenue forecasts of the Treasury and the Congressional Budget Office, and differing federal program funding and spending levels. Mercator also assists AASHTO in developing its own forecast of receipts and modeling HTF scenarios implied by different legislative proposals.