This report presents an inquiry into cases of pavement design, construction and maintenance in which distress has been observed instigated by deeper subgrade or by inadequate attention for the interaction between subgrade and pavement structure. Almost all cases are situated in areas with subgrade of poor to marginal bearing capacity. The cases are classified according to traffic; cross-section and elevation; moisture, groundwater, weather and temperature; aggregates in the pavement structure and subgrade. Each case starts with a brief introduction description followed by a description of the main problems. The analysis reveals the main cause of distress and tries to explain for its origin. The next step describes feasible off-the-shelve solutions or indicates in which direction future improvements should be found. The report ends with reflections on future actions to develop an integral approach for pavement design. Recommendations are made for issues which should be elaborated in computations with complex numerical models (Finite Element Model).