Designing Pavement Drainage Systems: The MnDRAIN Software

This report outlines the development of a suite of computer codes collectively referred to as MnDrain. These codes, embedded in a standard spreadsheet program, provide a user-friendly environment in which the consequences of an edge drain design decision can be investigated. The purpose of an edge drain is to remove moisture from the granular base of the road system. The rate at which moisture is removed will depend on the geometry and materials used in the base and the soil type in the subgrade. MnDrain allows for evaluation of a given drain design against Federal Highway Administration requirements. In MnDrain, the user can chose from three basic scenarios, select material types and adjust geometries for each scenario, and calculate the moisture removal versus time curve over a two-hour drainage time. The work in this report shows that MnDrain is easy to use, flexible, and produces accurate approximate solutions of the Richard's model of variable saturated flow in a layered media. MnDrain also offers the advantage of offering free access to all source codes, which means that MnDrain can be reconfigured to deal with a large array of pavement drainage issues.