Division 2.1.2

United Kingdom

The stopping distance shall be the distance covered by the vehicle from the moment when the driver begins to actuate the control device of the braking system until the moment when the vehicle stops; the initial vehicle speed (v₁) shall be the speed at the moment when the driver begins to actuate the control device of the braking system; the initial speed shall not be less than 98 % of the prescribed speed for the test in question. The mean fully developed deceleration d_m shall be calculated as the deceleration averaged with respect to distance over the interval v_b to v_e according to the following formula:

d_{m} = \frac{v_{2}^{b} - v_{2}^{e}}{25,92 (s_{e} - s_{b})} m ∕ s^{2}

Where:

v₁

initial vehicle speed calculated as described in the first subparagraph

v_b

vehicle speed at 0,8 v₁ in km/h

v_e

vehicle speed at 0,1 v₁ in km/h

s_b

distance travelled between v₁ and v_b in metres

s_e

distance travelled between v₁ and v_e in metres

The speed and distance shall be determined using instrumentation having an accuracy of ± 1 % at the prescribed speed for the test. The d_m may be determined by other methods than the measurement of speed and distance; in this case, the accuracy of the d_m shall be within ± 3 %.