LIGHTLY TRAFFICKED ROADS--JAPAN

IN JAPAN MOST LOCAL MATERIALS DO NOT HAVE THE QUALITY REQUIRED FOR SUBGRADES AND SUBBASES UNLESS TREATED WITH A STABILIZING AGENT SUCH AS CEMENT, LIME OR A BITUMINOUS MATERIAL. THERE ALSO EXISTS THE PROBLEM OF FINDING A PRACTICAL WAY OF REDUCING MOISTURE CONTENT ECONOMICALLY. A SURVEY OF THE PERFORMANCE OF LIGHTLY TRAFFICKED ROADS HAS BEEN CARRIED OUT ON A NATIONAL SCALE. ACCORDING TO THE RESULTS OF THE SURVEY OBTAINED SO FAR, THE DEFLECTION OF THE PAVEMENT SURFACE UNDER A DOUBLE AXLE LOAD OF 4 TONS MEASURED BY MEANS OF THE BENKELMAN BEAM WAS BELOW 1.5 MM FOR ABOUT 85% OF ALL THE ROADS. THE RATE OF CRACKING IS USED TO EVALUATE PAVEMENT SERVICEABILITY. THE MAJOR FACTORS RESPONSIBLE FOR A HIGH RATE OF CRACKING ARE THE TYPE AND MATERIAL OF THE SURFACE COURSE, DEGREE OF BENKELMAN DEFLECTION, K-VALUE ON THE BASE, AND TRAFFIC VOLUME. RATE OF CRACKING IS USED TO DECIDE THE PROPER TIMING FOR CARRYING OUT MAINTENANCE AND REPAIR WORK ON LIGHTLY TRAFFICKED ROADS. A 5% RATE OF CRACKING IS TAKEN AS AN INDICATION THAT A PARTIAL SEALING COAT IS NECESSARY AND 20% RATE OF CRACKING THAT AN OVERALL SEALING COAT IS NEEDED. FROM THE CORRELATION BETWEEN THE BENKELMAN DEFLECTION VALUE OF DIFFERENT TYPES OF SURFACE COURSES, K-VALUE ON THE BASE, TRAFFIC VOLUME AND RATE OF CRACKING, IT WAS FOUND THAT: (1) THE K-VALUE ON THE BASE UNDER THE PENETRATION MACADAM SURFACE COURSE OF LIGHTLY TRAFFICKED ROADS SHOULD BE MORE THAN 20 KG/CC IN ORDER TO CARRY TRAFFIC FOR AT LEAST ONE YEAR BEFORE APPLYING AN OVERALL SEALING COAT. (2) ON THE RECENTLY CONSTRUCTED PAVEMENTS OF LIGHTLY TRAFFICKED ROADS, REPAIRS SUCH AS APPLYING AN OVERALL SEALING COAT WILL BE NECESSARY AFTER 3 TO 5 YEARS. (3) IT IS EXPECTED THAT IF THE BENKELMAN DEFLECTION VALUE IS AROUND 1.6 MM UNDER A DOUBLE AXLE LOAD OF 4 TONS (2.0 MM UNDER A 5-TON DOUBLE AXLE LOAD), MINOR REPAIRS SUCH AS SUPPLYING A PARTIAL SEALING COAT WILL BE NECESSARY AFTER 1 TO 3 YEARS. IN KYUSHU, SLOPES OF CUT AND FILL OF SHIRASU (A SPECIAL VOLCANIC ASH SOIL) WERE DAMAGED BY HEAVY RAINS AND SERIOUS DISASTERS ENSUED. AS A PRECAUTION AGAINST DAMAGE BY HEAVY RAINFALLS, SLOPES WERE CONSTRUCTED ALMOST VERTICALLY. IF AFFECTED BY EARTHQUAKES, HOWEVER, SLOPES CONSTRUCTED IN THIS WAY PROVE VERY UNSTABLE. LESS STEEP SLOPES WITH ANTI-EROSION SOIL CEMENT LAYERS HAVE THEREFORE BEEN RECENTLY RECOMMENDED AND PUT INTO PRACTICE. MAINTENANCE ON GRAVEL ROADS COSTS 100,000 TO 200,000 YEN PER KM ANNUALLY. IN GENERAL, THE COST OF MAINTAINING GRAVEL ROADS IS MUCH HIGHER THAN THAT OF OTHER ROADS. SEALING COATS AS A DUST PREVENTATIVE TREATMENT ON LIGHTLY TRAFFICKED ROADS COST 180,000 YEN PER KM. HOWEVER, IN THE MATTER OF ROAD MAINTENANCE IN JAPAN THIS METHOD OF SURFACE TREATMENT TAKES PRECEDENCE.

  • Supplemental Notes:
    • QUESTION VII ANS-10
  • Authors:
    • Takahashi, K
  • Publication Date: 1971

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  • Accession Number: 00233474
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Apr 11 1974 12:00AM