The Road to Drained Pavements

by Raymond A. Forsyth, (F.ASCE), Chf.; Transportation Lab., California DOT, Sacramento, CA,
Gordon K. Wells, Concrete Pavement Rehab and Pavement Drainage Specialist; Transportation Lab., California DOT, Sacramento, CA,
James H. Woodstrom, (M.ASCE), Concrete Pavement Specialist; Transportation Lab., California DOT, Sacramento, CA,


Serial Information: Civil Engineering—ASCE, 1987, Vol. 57, Issue 3, Pg. 66-69


Document Type: Feature article

Abstract: In California, a fast-draining base course within the pavement structure is now the preferred design. For the first time, the 1987 edition of the California Highway Design Manual recommends this option. And for the first time also, the 1986 edition of the AASHTO Guide for Design for Pavement Structures modifies the flexible and rigid pavement design approaches to take advantage of improved pavement performance gained by good drainage. The drainage layer keeps the subbase beneath it drier and thus stronger. So the drained pavement can be expected to last longer. Three innovations are described that have helped make this new design practicable—the coming of geotextiles, the asphalt-treated permeable materials, and pavement edge drains. Case histories are given of some notable attempts to introduce in-pavement drainage in the past 10-15 years. Caltrans predicts its new rigid pavements with the new base course will last 50% longer than their undrained counterparts, and its new flexible pavements, 33% longer. And life-cycle costs are expected to drop—the drained rigid design is expected to cost 35% less per sq yd per year than the undrained, and the drained flexible pavement, 19% less.

Subject Headings: Pavements | Base course | Drainage | Life cycles

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