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Portable equipment will help to increase overweight enforcement

27th September 1974
Page 72
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Page 72, 27th September 1974 — Portable equipment will help to increase overweight enforcement
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Which of the following most accurately describes the problem?

This is the second article in a short series on the enforcement authorities' proposals for intensification of roadside weighing checks by Johnny Johnson

FROM the description, last week, of the proposals by the Department of the Environment and the local authorities weights and measures inspectorate for increasing roadside weight checks, it will be apparent that operators will have to pay much more critical attention to vehicle permitted weights.

The delay in bringing legislation already on the Statute Book into operation could alone ensure that the extensive checks will not be mounted till early next year. Added to this, however, could be further delay caused by the anxiety of the two organizations that the apparatus to be used will be accurate and that ensuing evidence will stand up during a subsequent prosecution.

Fundamentally, there is no disagreement between the two on a basic specification for the dynamic weighing equipment. Both agree on the method of weighing and the procedure and manufacturers are now engaged on producing acceptable equipment.

Announced only recently as already available, the Weighwrite ADS3 marketed by Smiths Industries Ltd is under consideration for use in the proposed checks and a similar apparatus manufactured by W and T Avery Ltd is undergoing extended trials to ensure accuracy under operating conditions.

Both these equipments fulfil the basic specification drawn up by the enforcement authorities and differ only in the appearance of the electronic recording console. The weighing beam is similar in construction and appearance both having similar installation requirements. These are critical to the accuracy of the weighing.

The beam requires a concrete-faced pit measuring loft by 2 ft 6 in and at least 91,6 in deep. Neither 1'as been produced to exact metric equivalents. However, it is the approach and departure aprons which must be laid to precise measurements to ensure the accuracy of the weighing. This is recommended to 'be at least 40 ft at each side of the beam installation.

At Avery's Smethwick works, it has been possible to install the equipment immediately before a static weighbridge so that the importance of the approach to the beam could be assessed.

Recommended standard

Weighing first on the dynamic equipment and then on the weighbridge, it has been possible to determine the effect of imprecise concrete laying accurately. From the experience gained, Avery recommends that the maximum practical standard of level should be maintained between the platform and approach and exit road for a length at least equal to the longest wheelbase. The deviation for each road should not exceed plus or minus 1/4 in for the 20 ft nearest to the platform and plus or minus 3/8 in for the remainder.

In addition, it is recommended that there should be sufficient reasonably level road on the approach side — 20 ft at least — to allow for acceleration before the first axle reaches the beam.

From this it will be apparent that an operator considering installing similar equipment in his premises will need at least 100 ft of clear speace in which to site it.

The speed at which the vehicle is driven over the beam is also critical. Weighwrite equipment requires the driver to maintain a speed of up to 2.2 mph while Avery specify a speed not exceeding 3 mph. This appears to be part of the reason for the provisions contained in the Road Traffic Act 1974 which allows the enforcement staff to direct the driver to conform to particular driving instructions.

Load cells detect when a weight greater than 1 tonne (1 ton 351b) is transmitted to the beam and a ratioing system between the cells indicates that the wheels are completely on the platform. The weight is displayed on the console and printed on a paper roll when the ratioing system indicates that the wheels are about to leave the platform.

Console recording

Should the speed of the vehicle exceed that stipulated this will be indicated to the load cells by the time taken by the wheels to traverse the beam and the console will record the fact. On the Weighwrite apparatus this will be shown by a print out in red and on the Avery by the illumination of a red warning light.

Here it should be pointed out that though the print-out ticket will indicate the date and time of the weighing, there is no indication as to the actual vehicle weighed. Prudence counsels that some method of recording there the vehicle registration or fleet number should be devised to prevent any difficulty in vehicle identification.

The weight of the last axle to pass over the beam remains displayed on the console till the completion of the next axle weighing when the cycle is repeated till all axles have passed over the beam and the weight individually recorded. Both equipments will add up the axle weights to give a gross vehicle weight, but this facility will be at an extra cost.

At a recent demonstration of one of these equipments in which the vehicle was weighed in reverse, I asked that the performance should be repeated with the vehicle driven forward. This produced slightly different axle weights. (See Bird's Eye View CM August 23).

However, I was told subsequently that I was somewhat unfair in that I should have asked that the vehicle should be weighed in forward gear in the same direction as it was weighed originally before passing judgment. It was held that the weights would then probably have corresponded. Inci dentally, this suggestion was not from the manufacturer of the equipment.

Although the apparatus, in both cases, is designed to be portable and a trolley has been designed to be hauled by a Land-Rover, there is no reason why either could not be used as a permanent installation. However, operators in certain trades — such as carrying quarry products from different sources for instance — could find that the portable facility would save money. In any case, these equipments are quoted as cheaper than a conventional weighbridge.

The cost

The cost installed, is likely to be in the range of about £7,000. Weighwrite quotes £2,750 in basic form or £3,060 with optional gross weight totaller. Add to this the roadwork and electrical work necessary plus a probable shelter for the operator and the console and it will be apparent that the whole cost could be about double the cost of .the equipment.

Next week: the legislation up to date and the penalties for overloading.

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