HYDRAULIC REQUIREMENTS OF PERMEABLE BASES

To address the need for increased drainage within the pavement system, open-graded permeable materials (OGPM) are finding their way into standard design sections throughout the country. The design requirements of the OGPM to handle surface water infiltration are reported. Infiltration rates and required permeabilities of the OGPM are calculated for a range of conditions typical for pavement design. The effects of pavement geometry on required permeabilities, including cross slope, longitudinal gradient, and drainage layer thickness and width, are discussed. Analysis of selected materials, typical for use in Illinois, is completed to determine appropriate permeabilities.