Document ID: chunk:federal_register_of_legislation:F2024L00446:reg:6:p4
Version: federal_register_of_legislation:F2024L00446
Segment Type: reg
Provision Reference: reg 6 (pt 4/4)
Character Range: 883792–885753

The overlapped speed may be less than 10 km/h but shall not be less than 5 km/h. In this case, overlap criterion (b) shall be checked by either extrapolating the polynomial curves for the lower and higher speed segment to a 10 km/h overlap, or by comparing the average force in the specific speed range.
              4.3.1.3.5. It is recommended that coastdown runs should be conducted successively without undue delay between runs. If there is a delay between runs (e.g. for a driver break, checking vehicle integrity, etc.), the vehicle shall be warmed up again as described in paragraph 4.2.4. and the coastdown runs shall be re-commenced from this point.
              4.3.1.4. Coastdown time measurement
              4.3.1.4.1. The coastdown time corresponding to reference speed as the elapsed time from vehicle speed (vj + 5km/h) to (vj – 5 km/h) shall be measured.
              4.3.1.4.2. These measurements shall be carried out in opposite directions until a minimum of three pairs of measurements have been obtained that satisfy the statistical precision pj defined in the following equation:
           where:
                  pj is the statistical precision of the measurements made at reference speed vj;
            is the number of pairs of measurements;
                   is the harmonic average of the coastdown time at reference speed vj in seconds given by the following equation:
              where:
                   is the harmonic average coastdown time of the ith pair of measurements at velocity vj, seconds, s, given by the following equation:
              where:
                       are the coastdown times of the ith measurement at reference speed vj, in seconds, s, in the respective directions a and b;
                   is the standard deviation, expressed in seconds, s, defined by:
              h is a coefficient given in Table A4/4.
              Table A4/4
       Coefficient h as a function of n

n   h    n   h