HARMONIZATION OF BRAKING REGULATIONS - REPORT NUMBER 6: TESTING TO ADDRESS SURFACE FRICTION AND VEHICLE BRAKING EFFICIENCY COMMENTS TO THE SNPRM. INTERIM REPORT

This report describes testing conducted to address certain comments to the Supplemental Notice of Proposed Rulemaking (SNPRM) for FMVSS 135 (Notice 4) regarding surface friction measurement and vehicle braking efficiency. Traction trailer tests were conducted comparing two reference tires, the ASTM E501 and the Standard Reference Test Tire (SRTT), on five surfaces at various speeds at seven different times. Tests were also conducted on seven passenger cars to evaluate the ECE Regulation 13 Annex 13 test procedure for determining peak coefficient of friction and braking efficiency. The results of the Annex 13 peak coefficient of friction measurements were compared to traction trailer tests with the same tires and the Annex 13 efficiency measurements were compared to results of tests on a Road Transducer Plate (RTP) facility.