MODIFIED C.B.R. FLEXIBLE-PAVEMENT DESIGN

THE MODIFIED C.B.R. CONTROLS (1) OVERALL THICKNESS OF PAVEMENT, BASE, SUBBASE, AND THAT PORTION OF THE BASEMENT SOIL CLASSED AS SELECTED EMBANKMENT AND (2) THE THICKNESSES AND QUALITY OF THE SELECTED EMBANKMENT AND SUBBASE. THE BASE AND PAVEMENT HAVE HAD NO TEST REQUIREMENTS FOR STABILITY, OTHER THAN THE WYOMING STABILITY TEST, SO THEY HAVE BEEN DESIGNED BOTH FOR THICKNESSES AND QUALITY BY PAST EXPERIENCE PLUS GRADATION, LIQUID LIMIT, PLASTICITY INDEX, AND WEAR TESTS. A TEST PROCEDURE IS NOW BEING PUT INTO PRACTICE TO ALLOW A BETTER SELECTION OF BASE AND PAVEMENT AGGREGATES. INCLUDED ARE TABULATIONS OF: (1) ROADWAY AND PAVEMENT WIDTHS, ALSO SURFACING WIDTHS, BASED ON TRAFFIC AND STATE HIGHWAY SYSTEM; (2) TRAFFIC VARIATIONS WITHIN EACH STATE HIGHWAY SYSTEM; (3) SEVERAL NEAR TYPICAL HIGHWAY PROJECTS SHOWING NUMBER OF SOIL SAMPLES TAKEN, NUMBER OF DIFFERENT DESIGNED THICKNESSES, ETC., FOR BOTH THE PRELIMINARY AND CONSTRUCTION STAGES; AND (4) THE OPINIONS OF THE VARIOUS ENGINEERS OF THE WYOMING HIGHWAY DEPARTMENT AS TO THE MERITS AND WEAKNESSES OF THE PRESENT DESIGN. /AUTHOR/