The Measuring Instruments (Non-Prescribed Instruments) Regulations 2006

Automatic Rail-weighbridges

50.—(1) In addition to the requirements set out in paragraphs 44 and 45, the following specific requirements shall apply in relation to automatic rail-weighbridges.

(2) Accuracy classes

Automatic rail-weighbridges are divided into four accuracy classes as follows:

(i) 0.2;

(ii) 0.5;

(iii) 1; and

(iv) 2.

(3) MPE

(a) The MPEs for weighing-in-motion of a single wagon or a total train are shown in Table 15.

Table 15

Accuracy class	MPE
0.2	± 0.1 %
0.5	± 0.25 %
1	± 0.5 %
2	± 1.0 %

(b) The MPEs for the weight of coupled or uncoupled wagons weighing-in-motion shall be one of the following values, whichever is the greatest:

(i) the value calculated according to Table 15, rounded to the nearest scale interval;

(ii) the value calculated according to Table 15, rounded to the nearest scale interval for a weight equal to 35% of the maximum wagon weight (as inscribed on the descriptive markings);

(iii) one scale interval (d).

(c) The MPEs for the weight of train weighing-in-motion shall be one of the following values, whichever is the greatest:

(i) the value calculated according to Table 15, rounded to the nearest scale interval;

(ii) the value calculated according to Table 15, for the weight of a single wagon equal to 35% of the maximum wagon weight (as inscribed on the descriptive markings) multiplied by the number of reference wagons (not exceeding 10) in the train, and rounded to the nearest scale interval;

(iii) one scale interval (d) for each wagon in the train, but not exceeding 10 d.

(d) When weighing coupled wagons; the errors of not more than 10% of the weighing results taken from one or more passes of the train may exceed the appropriate MPE given in paragraph 3(b), but shall not exceed twice the MPE.

(4) Scale interval (d)

The relationship between the accuracy class and the scale interval shall be as specified in Table 16.

Table 16

Accuracy class	Scale interval (d)
0.2	d ≤ 50 kg
0.5	d ≤ 100 kg
1	d ≤ 200 kg
5	d ≤ 500 kg

(5) Measurement range

(a) The minimum capacity shall not be less than 1 t, and not greater than the value of the result of the minimum wagon weight divided by the number of partial weighings.

(b) The minimum wagon weight shall not be less than 50 d.

(6) Performance under influence factor and electromagnetic disturbance

(a) The MPE due to an influence factor shall be as specified in Table 17.

Table 17

Load (m) in verification scale intervals (d)	MPE
0 < m ≤ 500	± 0.5 d
500 < m ≤ 2 000	± 1.0 d
2 000 < m ≤ 10 000	± 1.5 d

(b) The critical change value due to a disturbance is one scale interval.