Design Guidelines for Subsurface Roadway Drainage Systems

Poor drainage of asphalt pavements causes the pavement to undergo several types of distress, such as stripping, potholes, and others. The aim of this book is the development of guidelines to select proper design parameters of subsurface roadway drainage systems. This comprised the investigation of a variety of roadway cross-section configurations using computer modelling. The investigation started with evaluating the hydraulic situation under a selected roadway with many cross-section configurations in a water-logged area, in both cases of the presence and absence of many design alternatives of a subsurface drainage system. Then, the optimum parameters of each design alternative of the drainage system were determined to lower the groundwater table to a safe level under each configuration of the roadway cross-section. A microscopic groundwater flow model was created in Processing Modflow to simulate the hydraulic situation under the roadway cross-section in both cases of the drainage conditions. A cost analysis was performed in both cases of un-drained and drained roadway cross-sections including all configurations of the roadway cross-section and the roadway drainage system.