NEW DEVELOPMENTS IN BPR ROUGHNESS INDICATOR AND TESTS ON CALIFORNIA PAVEMENTS

THE ROUGHNESS INDICATOR WAS DEVELOPED BY THE BUREAU OF PUBLIC ROADS TO PROVIDE STANDARDIZABLE EQUIPMENT FOR MEASURING ROAD SURFACE ROUGHNESS. RESEARCH WITH THE UNIVERSITY OF CALIFORNIA HAS CONTINUED TO IMPROVE ITS ACCURACY AND CONSISTENCY AS A STANDARDIZABLE UNIT AND TO OBTAIN RECORDS OF ROAD ROUGHNESS OF THOUSANDS OF MILES OF PAVEMENTS ON THE STATE HIGHWAYS, CITY STREETS AND ON BRIDGES IN ALL PARTS OF CALIFORNIA. TESTS WERE CONDUCTED TO DETERMINE THE LIMITATIONS OF ACCURACY PROVIDED BY THE BPR DOUBLE BALL CLUTCH INTEGRATOR DESIGN AND ALSO THE ACCURACY OF AN INTEGRATOR CONSTRUCTED WITH A COMMERCIALLY AVAILABLE CLUTCH. MEASUREMENTS WERE MADE TO DETERMINE THE EFFECT OF CHANGING THE SIZE OF THE TEST TIRE FROM 6.00 BY 16, WHICH IS NO LONGER AVAILABLE, TO A 6.70 BY 15 SIZE TIRE WHICH IS AVAILABLE. THE EFFECTS WERE MEASURED OF AN IMPROVED LEAF- SPRING BEARING DESIGN AND OF THE USE OF STANDARD UNIVERSAL JOINTS INSTEAD OF BALL-SOCKET JOINTS IN ATTACHING THE DASHPOTS TO THE FRAME OF THE TRAILER. THE EFFECTS OF VARYING AMOUNTS OF OUT-OF-ROUNDNESS OF THE TEST TIRE WERE MEASURED ON VARIOUS ROAD SECTIONS. IT WAS FOUND THAT THE ROAD ROUGHNESS INDEX IN INCHES PER MILE FOR CERTAIN PAVEMENTS WAS INCREASED BY APPROXIMATELY 50 PERCENT DUE TO AN OUT-OF- ROUNDNESS OF 0.05 INCHES WHICH CORRESPONDS TO THE AMOUNT OF OUT-OF-ROUNDNESS FREQUENTLY OBSERVED IN MEASUREMENTS OF PASSENGER CAR TIRES BY ATTENDANTS AT TIRE AND WHEEL ALIGNMENT SHOPS. TO PROTECT THE TEST TIRE AND ROUGHNESS EQUIPMENT FROM DAMAGE AND EXCESSIVE WEAR IN MOVING IT FROM ONE TEST SECTION TO THE NEXT TEST SECTION, A SPECIAL OUTRIGGER TRAILER WAS DEVELOPED TO CARRY THE TEST TRAILER IN A SUSPENDED POSITION BY THE USE OF A HOIST AND SPECIAL CLAMPING DEVICES. DETAILED SHOP DRAWINGS FOR THE OUTRIGGER TRAILER HAVE BEEN PREPARED. THE RESULTS OF ROUGHNESS MEASUREMENTS FOR ALL OF THE MAJOR TYPES OF PAVEMENT SURFACES USED ON STATE HIGHWAYS, CITY STREETS, AND ON VARIOUS TYPES OF BRIDGE FLOORS ARE REPORTED, ANALYZED AND CORRELATED WITH THE DESIGN FEATURES, AGE OF THE PAVEMENT AND CONSTRUCTION METHODS USED IN BUILDING THESE SURFACES. /AUTHOR/

Media Info

  • Monograph Title: Road roughness and slipperiness: some factors and test methods
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00206786
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Jun 18 1994 12:00AM