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for weighbridges not used for end-andend weighing, the whole of the surfaceof the approach is within 2 of level(horizontal) measured from the endnext to the platform;for weighbridges used for end-and-endweighing, the approaches are within0.25 of level (horizontal) measuredfrom the end next to the platform.the clearance from the external edgesof the platform must be wide enoughfor servicing, maintenance anddrainage and must be free fromobstructions that may interfere with theoperation or accuracy of theweighbridge; andthe load cell footings must be stable.3.7 PitIf a weighbridge has one or more pits:each pit entrance must be covered;each part of the underwork must befreely accessible; andpits must be kept free from anyaccumulation of water, mud or debris,and be free-draining or be providedwith automatic mechanical drainage.For multi-platform weighbridges, the deadspace (if applicable) between the platformsof the weighbridge shall be level and in thesame plane as each of the platforms.See Table 1 for more information on in thesame plane.3.6 PlatformEach platform of a weighbridge must becomposed of concrete, steel or otherapproved material.3.8 Electrical and Electronic DevicesIf a weighbridge is equipped with electricalor electronic devices they must be protectedfrom electrical and electronic interferenceand the rays of the sun. Also the load celldata plate must be accessible so it may beread with ease.If a weighbridge has more than oneplatform:the dead space between each platformmust not exceed 2 m;each platform must operate in a mannerthat does not affect the operation of anyother platform;the upper surface of a platform shouldbe in the same plane as the uppersurface of each other platform; anda summing indicator must be installed.4.CHECKING A WEIGHBRIDGEThe operator must make sure theweighbridge always operates correctly andadvise the public weighbridge licenseewhenever there is a problem. To achieve this,an operator should:visually inspect the weighbridge at thebeginning of each shift (see clause 4.1);conduct regular checks which mightindicate a problem with weighbridgeaccuracy (see clauses 4.2 to 4.5); andmonitor performance (keep records ofthe tare mass of specific vehicles andreport unexplained variations in mass).Results can be recorded on the checklist.If a weighbridge does not have a pit:the clearance under the lowest live partof the platforms must be at least150 mm;the floor between load cell supportsmust be composed of concrete at least75 mm thick, effectively drained andkept free from any accumulation ofwater, mud or debris;Table 1. Defining level for weighbridge approachesDistance from end ofweighbridge (m)Maximum deviation for 0.25 ( .6Maximum deviation for34.9 69.8 104.8 139.7 174.6 209.5 244.4 279.4 314.3 349.2 2.0 ( mm)1/20134 of 22Weighbridge Operators Manual v5.0

4.2 Zero Operation and IndicationWhen it is suspected a weighbridge willproduce an incorrect measurement,withdraw the weighbridge from use until itis repaired, tested and marked with averification mark (clause 3.1). If it cannotbe repaired the public weighbridge licenseemust inform NMI.Note: Weighbridges should also complywith the relevant requirements inclause 3.The operator must ensure the indicator is atzero or the steelyard is in balance before thevehicle drives onto the platform. Alwayszero/balance the weighbridge in accordancewith the manufacturer’s instructions.The operator should also observe theindicator after the vehicle has left theplatform to ensure it returns to zero/balance.During wet weather it is important to checkthe zero/balance frequently to allow for theaccumulation of water on the platform.4.1 Visual InspectionRefer to the suggested checklist on the nextpage and also check:4.3 Zero TrackingThere is a continuous gap between theplatform and the edge of theweighbridge surround to preventbinding. Stones or other foreign matterjammed between the platform and itssurrounds may cause binding.There is no water, mud or debris on theplatform. Water can accumulate on theplatform due to rain or run-off from avehicle being weighed. Excess watercan affect zero/balance.There is no water, mud or debris underthe weighbridge. Loose loads, such assand, can accumulate in the pit or buildup under the platform and affect zero/balance (see clause 3.7).A weighbridge with zero tracking willautomatically return to zero if the amountleft on the platform does not exceed half ascale interval. This can be up to 10 kg on aweighbridge with 20 kg scale intervals.However if sufficient debris is allowed tobuild up on the platform the weighbridgewill not return to zero/balance and theplatform will need to be cleaned in order forthe weighbridge to return to zero/balance.4.4 EccentricityThe eccentricity check is designed to ensurethe weighbridge weighs the same regardlessof where the load is placed on the platform.To complete this check:Place a forklift (5 to 6 t) in the centre ofthe platform and note the reading.The weighbridge structure is in goodcondition with no lose bolts and nobroken, missing or rusty components.Progressively place the forklift over theload bearing points (knife edges or loadcells) until all load bearing points havebeen tested. Record the indications ineach position. It is good practice toensure there is no more than one scaleinterval variation between all theindications.The weighbridge approaches are ingood condition and the perimeters areclearly marked (see clause 3.5).Any steelyards or dial and weight unitmechanisms are in good workingcondition.Any digital indications are clear and allsegments work.Any additional indicating devices workand repeat the indication exactly.1/2013For example, on a weighbridge with a scaleinterval of 20 kg, a forklift that indicates5 960 kg in the centre of the platform isplaced over the four load bearing points.Indications ranging between 5 940 and5 960 kg or 5 960 and 5 980 kg areconsidered acceptable. However indicationsless than 5 940 or more than 5 980 kg arenot acceptable.5 of 22Weighbridge Operators Manual v5.0

Weighbridge ChecklistWeighbridge location .Operator’s name . Date of check .Visual Inspection (clause 4.1)Is/are the verification mark/s present and current?yes/noIs/are the platform/s free from binding?yes/noIs/are the platform/s free from accumulated water, mud and debris?yes/noIs the pit/space under the weighbridge free from accumulated water, mud and debris?yes/noyes/no/naIs the pit pump operational?Is the weighbridge in good condition?yes/noAre the weighbridge approaches smooth, level and in good condition and are theperimeters clearly marked?yes/noIs any steelyard in good working condition?yes/no/naAre any dial and unit weight mechanisms in good working condition?yes/no/naAre any digital indications clear and are all segments working?yes/no/naDo additional indicating devices work and repeat the indication exactly?yes/no/nayes/noIs the indicator set to zero?Check Results Pass Fail N/AZero tracking check (clause 4.3)Eccentricity check (clause 4.4). Pass Fail N/A.Comparison check A (clause 4.5.1)Difference between measurements of the same mass on Pass Fail N/Atwo different weighbridges. . – . . kg/tComparison check B (clause 4.5.2)Difference between the known mass of a test object and the mass of Pass Fail N/Athe test object indicated by the weighbridge . – . . kg/tComments.1/20136 of 22Weighbridge Operators Manual v5.0

4.5 Comparison Check4.5.1 Comparison Check AUse the direct measurement method (seeclause 6.1) to weigh a load of 50 to 70% ofthe capacity on both your weighbridge andanother verified weighbridge. After makingallowance for the weight of fuel used(10 L of diesel has a weight of about 8.3kg) compare the indications. The differenceshould not exceed two scale intervals.4.5.2 Comparison Check BWeigh a test object and compare theindication with the known mass of the testobject (i.e. the mass determined directlyafter verification). The difference shouldnot exceed one scale interval.Test objects should be:at least one-third the capacity of theweighbridge (although other suitablecapacities may be used); andretained solely as a test object and notbe subject to weight change.Complete the measurement ticket in anapproved form, in numerical order, withappropriate care and as soon as practicableafter making the measurement. For moreinformation see clause 7.To ensure the weighbridge is weighingaccurately at all times, conduct regularaccuracy checks (see clauses 4.2 to 4.5).When it is suspected a weighbridge willproduce an incorrect measurement,withdraw the weighbridge from use until itis repaired, tested and marked with averification markby an authorised verifier (clause 3.1). If itcannot be repaired the public weighbridgelicensee must inform NMI.The following basic procedure is goodpractice for determining the net weight of aload on a vehicle.1.Instruct the driver to approach theweighbridge slowly and to proceeddirectly onto the platform withoutturning or harshly applying brakes.2.Ensure the vehicle is completely on theplatform. Ensure no tyres are rubbingagainst anything because this willproduce inaccurate results.3.Weigh the vehicle using the appropriateweighing method. When the vehicle fits onthe platform you must use directmeasurement (clause 6.1) otherwise useend-and-end measurement (clause 6.2).Unless prohibited for occupationalhealth and safety reasons, ask thedriver and any passengers to get out ofthe vehicle and off the platform. It maynot be the same driver, or thepassengers could be missing, when thevehicle returns. (This is the appropriateprocedure for trade transactionshowever for law enforcement of roadrules the driver may be required to stayin the vehicle.)4.Use axle measurement (clause 6.3) todetermine the load on each axle or axlegroup.Weigh the loaded (or unloaded)vehicle. Record the gross (or tare) masson the measurement ticket as soon asthe weighing is completed.5.Once the vehicle returns, weigh theunloaded (or loaded) vehicle. Ensurethe tare (or gross) mass is included onthe measurement ticket as soon as theweighing is completed.5.WEIGHING PROCEDUREGenerally a weighbridge is used todetermine the weight of goods being carriedor to determine the load on each axle toensure the vehicle is not overloaded beforetravelling on a public road. Fees for the useof a weighbridge are not prescribed bylegislation.At the beginning of each shift visuallyinspect the weighbridge to ensure it is ingood working order (see clause 4.1).Before each measurement, make sure theweighbridge indicates zero (see clause 4.2).Note: End-and-end measurement may onlytake place on weighbridges permittedto conduct such measurements.1/20137 of 22Weighbridge Operators Manual v5.0

6.To obtain the net mass, subtract the taremass from the gross mass. Record thenet mass on the measurement ticket.Notes:1. Always determine measurements withappropriate care.2. Never use a weighbridge in conditionswhich affect its performance.3. Always keep the platform clean.4. Make sure the space between the frameand the platform is kept free fromobstructions.1/20135.6.7.8 of 22When tare and gross measurements aremade, the operation generally occurswithin 24 hours.Tare only and gross only measurementmust not be stored for more than 24hours.Registration numbers must be recordedand it is good practice to record theconfiguration of the vehicle/s (refer tothe chart below). This is to ensure thetare and gross masses recorded areidentified for the same vehicle and thevehicle configuration has not changedbetween measurements.Weighbridge Operators Manual v5.0

6.WEIGHING METHODSThe following method could be used forend-and-end measurement of a semi-trailer.6.1 Direct MeasurementDirect measurement is used when thevehicle fits on the platform; it is the mostaccurate weighing method and must beused whenever possibleDirect measurement is a single operation,namely the vehicle has all wheels of allaxles on one or more platforms of theweighbridge at all times.1.Position the prime mover on theplatform so the trailer axles are as closeas possible to the platform on the levelapproach.2.Record the weight of the prime mover(weight 1).3.Move the vehicle forward so the traileraxles are on the platform. Ensure theprime mover axles are as close aspossible to the platform on the levelapproach.4.Record the weight of the trailer axles(weight 2).5.To determine the total weight, addweight 1 and weight 2 together.6.2 End-and-End MeasurementEnd-and-end measurement is used when itis not possible to determine the mass of avehicle by direct measurement because theentire vehicle does not fit onto theplatform/s. As a result two measurementshave to be determined, one for the front andthe other for the rear of the vehicle.End-and-end measurement may only beperformed on a weighbridge that hassuitable approaches and is permitted toperform such measurements.Refer to clause 7, particularly clause 7.4, onhow to complete an end-and-endmeasurement ticket.Before weighing ensure the approaches tothe weighbridge:have a smooth and level surface;are in the same plane as the top of theplatform/s (see clause 3.5); andExampleTare mass prime mover (566 JVN)Tare mass trailer (QBB 932)Gross mass prime mover (566 JVN)Gross mass of trailer (QBB 932) 6.90 t 7.19 t 17.10 t 19.01 t1.Add the tare mass of the prime moverand trailer together to obtain the totaltare mass 6.90 t 7.19 t 14.09 t.2.Record this mass on the measurementticket.3.there are no items or mechanismsaffecting the measurement;Add the gross mass of the prime moverand trailer together to obtain

Weighbridge Operators Manual: A Guide for Operators who Conduct Public Weighings . Fourth edition — February 2012 Fifth edition — January 2013 National Measurement Institute Bradfield Road, Lindfield, NSW 2070 PO Box 264, Lindfield, NSW 2070 T (61 2) 8467 3600 F (61 2) 8467 3610 . during normal operating hours, unless: the vehicle is .