STOPPING ABILITY OF MOTOR VEHICLES SELECTED FROM THE GENERAL TRAFFIC

THE RESULTS OF TESTS ARE PRESENTED WHICH WERE CONDUCTED DURING 1955 ON MORE THAN 1,200 VEHICLES SELECTED AT RANDOM FROM THE GENERAL TRAFFIC. PAST AND PRESENT LEVELS OF BRAKE PERFORMANCE ARE COMPARED AND BRAKE PERFORMANCE IMPROVEMENT OF MOST VEHICLE TYPES SINCE 1949 HAS BEEN SMALL. CURRENT PERFORMANCE LEVELS ARE REPORTED ACCORDING TO VEHICLE TYPE, GROSS WEIGHT, VEHICLE CAPACITY, AND AXLE LOAD. THE OBSERVED LEVELS OF PERFORMANCE IN STOPS FROM 20 MILES PER HOUR FOR COMMERCIAL VEHICLES OPERATING IN THE GENERAL TRAFFIC STREAM WITH NORMAL LOADS AVERAGED ABOUT 25 FEET FOR 2-AXLE TRUCKS WITH A MANUFACTURER'S GROSS VEHICLE WEIGHT RATING OF 10,000 POUNDS OR LESS. THE AVERAGE LEVELS GENERALLY RANGED FROM 35 TO 45 FEET FOR OTHER 2-AXLE TRUCKS, FROM 40 TO 50 FEET FOR THE 3-AXLE TRUCKS, FROM 45 TO 55 FEET FOR TRUCK-TRACTOR-SEMITRAILER COMBINATIONS, AND FROM 55 TO 65 FEET FOR TRUCKS WITH FULL TRAILERS AND TRUCK-TRACTOR-SEMITRAILER AND FULL-TRAILER COMBINATIONS. THE TESTS ALSO REVEALED THAT MANY COMMERCIAL VEHICLES, EXCEPT FOR THE VERY LIGHT 2-AXLE TRUCKS, WERE INADEQUATELY BRAKED IN PROPORTION TO THE LOADS CARRIED ON INDIVIDUAL AXLES. HOWEVER, INDIVIDUAL TESTS PROVED THAT VEHICLES WITH AXLE LOADS AS HIGH AS 22,000 POUNDS CAN BE ADEQUATELY BRAKED. THE PERCENTAGES OF VEHICLES TESTED WHICH MET THE UNIFORM VEHICLE CODE SPECIFICATIONS FOR BRAKE-SYSTEM APPLICATION AND BRAKING DISTANCE PRESENT A LITTLE BRIGHTER PICTURE. SOME 92 PERCENT OF THE PASSENGER CARS AND 84 PERCENT OF EACH OF TWO CLASSIFICATIONS OF 2-AXLE TRUCKS WERE ABLE TO MEET THEIR RESPECTIVE DISTANCE SPECIFICATIONS OF 25, 30, AND 40 FEET, RESPECTIVELY. ABOUT 80 PERCENT OF THE 3- AND 4-AXLE TRUCK-TRACTOR-SEMITRAILER COMBINATIONS AND 3-AXLE TRUCKS, AND 38 TO 64 PERCENT OF THE LARGEST VEHICLE COMBINATIONS COMPLIED WITH THEIR CODE SPECIFICATION OF 50 FEET. ALSO OF INTEREST IS THE DEGREE OF COMPLIANCE WITH THE DECELERATION REQUIREMENT OF THE UNIFORM VEHICLE CODE. WELL OVER 99 PERCENT OF THE PASSENGER CARS MET THE DECELERATION SPECIFICATION OF 17 FEET PER SECOND PER SECOND. AT THE SAME TIME, ALL VERY LIGHT 2-AXLE TRUCKS AND 94 PERCENT OF OTHER 2-AXLE TRUCKS MET THE 14 FEET PER SECOND PER SECOND REQUIREMENT. SO DID 76 TO 85 PERCENT OF THE TRUCK-TRACTOR-SEMITRAILER COMBINATIONS AND 3-AXLE SINGLE-UNIT TRUCKS, 51 PERCENT OF THE TRUCKS WITH FULL TRAILERS, AND 69 PERCENT OF THE TRUCK-TRACTORS WITH SEMITRAILERS AND FULL TRAILERS. /AUTHOR/

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/oclc/1586080
• Supplemental Notes:
  • Vol 29, No 8, PP 177-195, 20 FIG, 16 TAB, 1 PHOT
• Authors:
  • PETRING, F W
• Publication Date: 1957-6

Media Info

• Serial:
  • Public Roads
  • Publisher: Federal Highway Administration
  • ISSN: 0033-3735
  • Serial URL: https://www.fhwa.dot.gov/publications/publicroads/
• Publication flags:

  Open Access (libre)

Subject/Index Terms

• TRT Terms: Automobiles; Axle load force; Braking; Commercial vehicles; Deceleration; Motor vehicles; Performance; Stopping distances; Testing; Tractor trailer combinations; Trailers
• Identifier Terms: Uniform Vehicle Code
• Subject Areas: Highways; Motor Carriers; Safety and Human Factors;

Filing Info

• Accession Number: 00222782
• Record Type: Publication
• Files: TRIS
• Created Date: Oct 13 1994 12:00AM