THE DEVELOPMENT OF TRENCHLESS PIPE DRAINAGE FOR BOXED PAVEMENTS

This paper gives a summary of the causes and effects of infiltration of water into road pavements from the surface. It discusses current methods of removing this water and investigates the concept of a trenchless pipe drainage system for boxed pavements. The paper traces the development and testing of a high crushing strength slotted asbestos cement pipe for this system and reports on the construction and performance of a pilot scheme involving 6 km of pipe. Laboratory research into the drainage performance of the pipe with two densely graded crushed rock sub-base materials is presented. The results include data relating drainage to compaction density, the effect of continuous and periodic infiltration on outflow rates, and fines removal. The paper concludes that a trenchless pipe drainage system in a free draining boxed pavement is effective in removing surface infiltration. Installed costs have proved to be at least 30 per cent less than for conventional trench drainage. The laboratory tests indicated that the system could be effective with boxed pavements constructed from non macadam type pavement materials, provided that the pavement material is shown to be sufficiently permeable to permit drainage (a). The number of the covering abstract of the conference is TRIS No. 368448. (TRRL)