VEHICLE DECELERATION IN BEDS OF NATURAL AND ARTIFICIAL GRAVELS

DECELERATION MEASUREMENTS OF VEHICLES RUNNING INTO BEDS OF LOOSE GRAVEL HAVE BEEN EXTENDED TO INCLUDE HEAVY VEHICLES, AND TO COVER PRIVATE CARS AT SPEEDS UP TO 98.2 KM/H (61 MILE/H). AT A GIVEN ENTRY SPEED, MEAN VALUES OF DECELERATION OBTAINED WITHOUT APPLICATION OF A VEHICLE'S BRAKES WERE FOUND TO BE DEPENDENT UPON THE CHARACTERISTICS OF THE ARRESTER BED INCLUDING THE SIZE AND SHAPE OF STONE, BUT TO BE SUBSTANTIALLY INDEPENDENT OF THE VEHICLE TYPE TESTED OR ITS ENTRY SPEED. MEASUREMENTS WERE ALSO MADE OF VEHICLE DECELERATION ON 0.6 M (2 FT.) DEEP BEDS OF 9.5 - 4.1 MM (3/8 - 3/16 IN) LIGHTWEIGHT AGGREGATE MATERIAL (LYTAG). FOR AN ENTRY SPEED OF 48 KM/H (30 MILE/H) THIS WAS 0.58 G WITHOUT APPLICATION OF THE VEHICLE BRAKES; COMPARABLE VALUES FOR NATURAL STONES 45.7 CM (18 IN) DEEP ARE 0.6 G FOR 9.5 - 6.3 MM (3/8 - 1/4 IN) ROUNDED GRAVEL, AND 0.45 G FOR 9.5 - 6.3 (3/8 - 1/4 IN) ANGULAR GRAVEL. ASSUMING THAT THESE VALUES STILL HOLD AT 96 KM/H (60 MILE/H), A VEHICLE ENTERING AN ARRESTER BED AT THIS SPEED WILL BE STOPPED IN A LENGTH OF ABOUT 64 M (210 FT) OF ROUNDED GRAVEL OR LIGHTWEIGHT AGGREGATE (E.G. LYTAG), AND ABOUT 82 M (270 FT) OF ANGULAR GRAVEL. THE MOST PROMISING USE FOR ARRESTER BEDS APPEARS TO BE TO PROVIDE ESCAPE ROUTES FROM LONG DOWN-GRADIENTS FOR VEHICLES WHICH EXPERIENCE BRAKE FAILURE. /A/RRL/

• Supplemental Notes:
  • Rrl Rept Lr 264, 11 PP, 3 FIG, 3 TAB, 2 PHOT, 1 REF
• Corporate Authors:

  MINISTRY OF TRANSPORT, LONDON (UK)

  ,    
• Authors:
  • JEHU, V J
  • Laker, I B
• Publication Date: 1969

Subject/Index Terms

• TRT Terms: Automobiles; Brakes; Deceleration; Failure; Gravel; Lightweight aggregates; Measurement; Speed; Stone; Trucks
• Subject Areas: Geotechnology; Highways; Motor Carriers; Safety and Human Factors; Vehicles and Equipment;

Filing Info

• Accession Number: 00220168
• Record Type: Publication
• Source Agency: Road Research Laboratory /UK
• Files: TRIS
• Created Date: Dec 12 1994 12:00AM