In 1986 the Arizona Department of Transportation constructed a 3,500-ft-long porous pavement experimental test section on State Route 87 in the Phoenix metropolitan area. The objectives of the project were to determine the constructibility and subsequent performance of porous pavement as a drainage system and pavement structure in an urban area and a desert environment. The porous pavement test section has performed satisfactorily for 5 years. Although a slight decrease in the infiltration rate has occurred, both the infiltration rate and the storage capacity are above the design values. The storage capacity of the pavement subbase and trench drain system has been underutilised. If a design intensity storm occurs during the remaining service life, this should be verified. Visual observation during rain storms has shown that the surface of the porous pavement section does not include sheet flow, which provides a marked difference in stripe delineation and pavement glare during night-time inclement weather driving as compared with conventional pavement. Mu-meter skid test results for the porous pavement section are comparable with those of conventional pavements (control). Material tests conducted on the pavement components indicate that the Marshall stability, resilient modulus, and asphalt cement viscosity of the open-graded asphalt concrete have increased with time. No cracking or significant surface deformation has occurred during the 5 years of service. Annual falling weight deflectometer testing was conducted to establish the changes in layer properties. To date, little change has occurred in the layer moduli except for the open-graded subbase, whose modulus has decreased with time. No unusual presence of moisture was detected in any layer of the pavement system. The subgrade moisture content has achieved equilibrium and less than optimum moisture content determined during the design process. (Author/publisher)
Abstract