WHY DO ROADS CORRUGATE?

OBSERVATIONS OF CORRUGATED ROAD SURFACES SHOW REGULAR SPACING, OR PITCH, OF THE CORRUGATIONS. A STRETCH OF CORRUGATED ROAD HAS AN UNMISTAKABLE PATTERN, QUITE DISTINCT FROM THE IRREGULAR DAMAGE OF RUTS AND POT HOLES. AN AVERAGE PITCH OF 29 INCHES WAS OBSERVED IN AUSTRALIA. THE PITCH IS SHORTER ON ROADS WHERE TRAFFIC MOVES MORE SLOWLY. THIS GAVE A CLUE TO THE IMPORTANCE OF SPEED IN FORMING CORRUGATIONS. EXPERIMENTS WERE CONDUCTED IN THE LABORATORY UNDER CONTROLLED CONDITIONS. A TEST TRACK OF 64 INCHES IN DIAMETER WAS USED WITH A MOTOR TO DRIVE THE WHEEL AT UP TO 10 MILES PER HOUR. THE AMPLITUDE OF CORRUGATIONS WAS MEASURED WITH A MICROMETER SCREW MOUNTED VERTICALLY IN A TRIPOD. MATERIALS USED WERE A FINE SIFTED SAND, GRAVEL, SAND WITH A WIDE RANGE OF PARTICLE SIZES AND RICE GRAINS, SUGAR AND SPLIT PEAS. ALL OF THESE MATERIALS CORRUGATED PROVIDED THAT THEY WERE DRY AND DID NOT COHERE. IT WAS OBSERVED THAT THERE IS A CRITICAL SPEED (ABOUT 4 MILES PER HOUR) THAT MUST BE REACHED BEFORE CORRUGATIONS WILL START, NO MATTER HOW LONG THE WHEEL RUNS. ABOVE THE CRITICAL SPEED THE CORRUGATION PITCH INCREASES IN PROPORTION TO SPEED. CORRUGATIONS ALWAYS TENDED TO FORM FIRST AT IRREGULARITIES ON THE TRACK. AT HIGHER SPEEDS, HOWEVER, THE CORRUGATIONS PROPAGATED SO QUICKLY THAT IT WAS DIFFICULT TO SEE WHERE THEY STARTED. CORRUGATIONS HAVE A SHORT PITCH WHEN THEY FIRST APPEAR. THE PITCH WOULD THEN GROW IN LENGTH AS THE CORRUGATIONS DEVELOPED IN AMPLITUDE. FINALLY, THE PITCH AND AMPLITUDE REACHED STABLE VALUES CORRESPONDING TO THE SPEED OF THE WHEEL. THE ENTIRE PATTERN OF CORRUGATIONS MOVES ALONG THE TRACK IN THE DIRECTION OF MOTION OF THE WHEEL.

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/00368733
• Supplemental Notes:
  • Vol 208, No 1, PP 128-136, 6 FIG, 4 PHOT
• Authors:
  • Mather, K B
• Publication Date: 1963-1

Media Info

• Serial:
  • Scientific American
  • Publisher: Scientific American Incorporated
  • ISSN: 0036-8733

Subject/Index Terms

• TRT Terms: Amplitude (Physics); Corrugations (Defects); Experiments; Fine grained soils; Gravel; Measurement; Micrometers; Motion; Sand; Spacing; Surface course (Pavements); Test tracks; Traffic speed; Wheels
• Uncontrolled Terms: Patterns
• Subject Areas: Highways; Pavements; Vehicles and Equipment;

Filing Info

• Accession Number: 00206764
• Record Type: Publication
• Files: TRIS
• Created Date: Aug 12 1994 12:00AM