Weight Tickets
The contractor shall provide a weight ticket for each load showing the required weight information for the procedure being used, the project number or contract description, the truck number, the date, and the type of material.

Automatic or Semi-Automatic Weighing
■   For weigh hoppers, batch scales, or silos on load cells, all tickets printed automatically shall include the gross weight, empty weight of the hopper or weight not discharged, net weight of material for each drop, and the total net weight for the load. When weighed under the semi-automatic procedure, the weighmaster may include on the ticket the calculated total net weight.
■   For batch scales, the batch weight and batch count are to be automatically printed under both procedures. The total net weight may be printed with a system or calculated by a weighmaster with a semi-automatic system.
■   For truck platform scales, all scale tickets printed automatically shall include gross weight, tare weight of the truck, and net weight of the load. For semi-automatic weighing the printer shall print the gross weight, and the weighmaster shall conduct all weighing and may enter by hand or by printer the tare weight of the truck and calculate the true net weight.

Manual Weighing
■   For manual weighing of loaded trucks (project quantities less than 10,000 Mg [10,000 tons]), scale equipment on truck platform scales may or may not include a mechanical ticket printer. A weighmaster shall include the gross and tare weights and calculate the net weight on the scale ticket. The engineer may arrange for weighing to be witnessed.

The inspector will collect the accompanying load ticket for each load of material on its arrival at the work site and check to see that the ticket has been validated by the scale inspector when such scale inspection is required.  The inspector will observe each load of delivered material to detect any obvious deficiencies in quality or in quantity and reject any loads which are unsatisfactory.

The inspector will sign or initial the scale ticket for each accepted load to verify the material was delivered and accumulate the tickets on a daily basis for determination of pay quantities.  Quantities for each day's operation shall be totaled and checked against the contract records and any discrepancy promptly resolved.

The requirement that an inspector personally receive all load tickets at the time of delivery may be relaxed only in cases of very small quantities or intermittent deliveries under conditions where the project engineer or inspector can visually determine the approximate quantity delivered.

On hot mix asphalt projects, it is permissible for a contractor's employee to collect the tickets and place them on a clipboard. An inspector must be present at the laydown operations at all times and observe the collection of the tickets.

Truck Platform Scale Approval
The specifications require that scales for weighing loaded trucks shall meet the requirements of the Iowa Department of Agriculture. A platform scale used for measurement of items such as crushed stone, base and subbase material, and hot mix asphalt mixtures, contracted for and measured by the Megagram (ton), shall be inspected by the Iowa Department of Agriculture.

Permanent scales, so inspected, have an official stamp conspicuously displayed.

Temporary scales, so inspected, have the same official stamp. If the scale is at a temporary plant location or quarry, the inspection may be identified by a certified report and affidavit.  A copy of the "Portable Scale Report" to be used for portable scales is included in Appendix 3-7. Use of the certified report and affidavit is subject to the following special limitations, and with these limitations inspection is official by the Iowa Department of Agriculture.

■   The scale is inspected by a registered scale technician. A report is then prepared that certifies the scale complies with State of Iowa regulations. A copy of the report shall be forwarded to the Iowa Department of Agriculture.
■   It is effective for 90 days at the same location; however, the effective period does not extend beyond the spring thaw.
■   Inspections made in the spring are after frost leaves the ground.
■   The certified report and affidavit shall expire when the scale is moved.

Weigh Hopper, Batch Scales, & Load Cell Approval
Weigh hoppers, batch scales, and load cells will be checked for accuracy against truck platform scales that meet the requirements of the Iowa Department of Agriculture during calibration and during use as described below.

The contractor shall have, reasonably available upon request, at least 10 standard 25 kg (50 pound) test weights for the purpose of testing and calibrating weighing equipment.  Whenever scales are checked with standard weights, the data showing scale readings versus increments of known standard loads should be recorded in the field notebook or on a calibration form and become a part of the permanent job record. It is the intention that contractor's personnel will be responsible for adding and removing the weights. Inspection personnel shall witness and document calibration or other scale checks.

When automatic or semi-automatic weighing is used, continuous direct observation of the weighing process by a scale inspector is not required. When weighing is not continuously observed, sufficient random checks should be made to assure the project engineer that the contractor's weighing procedures are accurate and the true net weight is recorded. This includes both verification weighing and check weighing.

Verification weighing is defined as a second weighing of the same load on the same scale, and applies only to truck platform scales. At least one verification weighing should be made daily when the pay quantity is weighed on truck platform scales. Verification weighings are made to determine the repeatability of truck platform scales. The verification weight should not be different from the initial weight by more than 0.1%.

Check weighing is defined as a second weighing of the same load on another certified truck platform scale. Check weighings shall be made to determine the accuracy for all types of weighing equipment. For check weighing of weigh hoppers, load cells or batch weight tickets, it will be necessary to also get the tare weight of the delivery truck and consider a suitable fuel adjustment to determine the accuracy of the total net weight. Recognizing that in a batch plant some material may remain in the mixing chamber after a drop, the results of two check weighings may be averaged.

One check weighing should be performed on the first day of hot mix asphalt production or aggregate weighing. One additional random check weighing should be performed for project quantities exceeding 4,536 Mg (5,000 tons). If these check comparisons had been made for another project within the time stipulated, documentation in the project diary will be satisfactory and separate checks will not be required.

If the check shows weighings that compare within the tolerances allowed, the scales should be considered satisfactory.

If the check shows weighings that do not compare within the tolerances allowed, the scales should be considered satisfactory only after the following additional investigations show it as warranted:

(1) The scale can be checked against another platform scale.
(2) The deviation of each scale from the true weight can be determined from the scale calibration prepared during the inspection if available. The scale operator is given this calibration, but is not required to keep it. The tolerance to be maintained is 1.8 kg per 900 kg (2 pounds per 1,000 pounds).

If one scale is heavy just within this tolerance and the other scale is light just within this tolerance, a difference in compared weights for a 23 Mg (50,000 pounds) load can be 90 kg (200 pounds) and still be legal and satisfactory.  Some allowance should be made for actual difference in weight because of gasoline 0.84 kg/L (7 pounds/gallon) if there is sufficient distance between scales.

For true verification and check weighing, selection of random loads shall be done without advance warning to the contractor. Allow a reasonable fuel adjustment, if appropriate.

Where random checks show errors beyond the tolerances specified in the specifications, the project engineer should review the weighing procedures used by the contractor and may require that the scales be inspected. The contractor shall take prompt action to make necessary repairs.  Should errors continue to be discovered, it will be necessary to suspend further weighing until the weighing procedures are correct and accurate. Further investigation is necessary when the error exceeds the tolerance in either the plus or minus direction.

Scale Checks for Sensitivity