THE PERFORMANCE OF A PAVEMENT DRAINAGE SYSTEM IN A BOXED PAVEMENT

This paper discusses the reasons for the recent resurgence of boxed construction in Australia and examines how subsurface drainage and permeable pavement layers can be used to avoid some of the earlier problems with this form of construction. This paper also describes field observations made of the performance of a subsurface drainage system installed in a boxed pavement on an embankment. The drainage system was installed to remove water that might infiltrate the road surface during the life of the road. It was concluded that (a) a properly designed pavement drainage system installed in a box pavement is an effective method of removing surface infiltration if at least one layer of the pavement is very permeable; (b) the presence of cold joints in asphaltic concrete pavements has a significant effect on the quantity of water entering the pavement; (c) low intensity rainfall resulted in surprisingly large quantities of water entering the untrafficked pavement; (d) techniques using an in-situ permeameter for estimating surface infiltration into pavements appear to give accurate indications of the order of magnitude of actual infiltration rates; (e) automatic monitoring of a variety of subsurface drainage systems, together with collection of data on the physical characteristics of the roadway, would significantly improve our understanding of the principles involved in the satisfactory drainage of pavements. (TRRL)