Drainage Modeling of Roadway Systems with Porous Friction Courses

The conventional nonpermeable asphalt pavement interface significantly modifies relationships between rainfall and runoff while also altering the coupled transport of particulate matter (PM), heat, and solutes. This study examines an original drainage design method for commonly utilized porous friction courses (PFC) promoting roadway system drainage, improved skid control, and in situ passive control of PM through infiltration-exfiltration of surface water by a pavement system PFC. This study presents a generalized mathematical model on the basis of physical modeling, which is utilized in the proposed design method. Specifically, for the geometric characteristics of a roadway, the rainfall intensity, and the mix design porosity characteristics, the method is utilized to evaluate the hydraulic response and thickness of the PFC to minimize ephemeral surface water films on the pavement. The method proves to be sufficiently robust to design the required spacing of pavement subsurface drains to minimize surface water films. Model results are synthesized into design nomographs to facilitate design solutions. The study illustrates applications of the design model and method for PFC construction. As with any drainage design model and method, field validation of the hydraulic response, for example through field permeameter testing, is require