austroads test method ag:am/t007 pavement deflection
Contents
1. Austroads Test Method AG AM T007 Pavement Deflection Measurement with a Deflectograph AUSTROADS TEST METHOD AG AM T007 PAVEMENT DEFLECTION MEASUREMENT WITH A DEFLECTOGRAPH 1 SCOPE This test method defines the procedure for measuring the maximum deflection and curvature of road pavements using a deflectograph Specific deflectograph machines may be known by proprietary names e g the VicRoads designed deflectograph is known as the Pavement Strength Evaluator PaSE The structural capacity of a pavement is evaluated by measuring the deflections of a pavement under a standard load applied on a single axle through dual rear wheels refer 4 1 b Testing is carried out at intervals of between 3 m to 7 m with measurements occurring simultaneously in both wheelpaths at a continuous speed up to 4 km h The procedure contained in Austroads Test Method AG AM T008 can be followed to undertake validation and repeatability of measurement checks for deflectograph equipment The test method has not however been verified by field experience and engineering judgement should be exercised when considering and acting upon the results obtained This test method does not address all occupational health and safety issues associated with its use It is the responsibility of the user to operate in accordance with appropriate legislation Deflectograph testing requires adequate traffic control The traffic control required for this test should be based2. d a minimum of 2 minutes waiting is required Additional recording of temperature shall be carried out if a new road or section is tested within the hour at the pavement surface at least every 5 minutes During testing the vehicle should maintain a near constant speed typically between 2 km h and 4 km h Care should be taken when testing over any major surface irregularities such as bridge joints rails tram tracks soeed humps or major potholes If it is suspected that traversing occurrences of such irregularities will result in damage to the test equipment the obstacle must be avoided or the test frame lifted and a new starting point used Such actions shall be noted and recorded Sudden transverse movements should be avoided and significant deviations from the test path are only permitted where the test lane is blocked e g by a parked or broken down vehicle When such a manoeuvre is necessary appropriate traffic control procedures should be exercised Any deviation from the test lane must be noted and reported Testing shall be terminated if continuation is likely to cause damage to the test assembly or vehicle Austroads 2011 Austroads Test Method AG AM T007 Pavement Deflection Measurement with a Deflectograph 7 Testing should be terminated by stopping the data acquisition system at the end of a measuring cycle The end point of the test should be recorded to the nearest metre Make copies of the resultant te
3. e pressures will vary with changes in the heat of the tyres it is important that pressure checks be conducted at operational tyre temperatures Position the truck on the road so that the tip of the test beam is located approximately above the start chainage point of the road section to be tested Definitively reference and record the starting point and intermediate and ending points Commence data acquisition in accordance with manufacturer s User Manual Steer the truck so that the tips of the test arms are in the centre of the traversed wheelpaths If it is not possible to track both wheelpaths simultaneously the left hand arm i e the one measuring the outer wheelpath should be given preference and a note made to that effect Use of the steering wheel of the truck should be limited to the absolute minimum necessary to steer the vehicle during the measuring phase If the pavement is known to contain asphalt measure and record either the shaded air temperature or the pavement temperature subject to safety and operational constraints If pavement temperature is to be measured it shall be determined and recorded against the appropriate chainage at the time of measurement at either of the following locations at a depth of 30 mm every hour using a temperature probe inserted into a 6 mm to 10 mm diameter oil filled hole drilled into the pavement stability of the temperature reading must be obtained before the temperature can be recorde
4. easurement arms are damaged 6 PROCEDURE 6 1 Pre test Set up 6 1 1 Daily and Other Periodic System Checks The daily pre survey and other relevant periodic system checks listed in the manufacturer s User Manual must be followed prior to commencing survey work 6 1 2 Traffic Control and Safety a Traffic control shall be carried out in accordance with locally applicable management procedures These will have been based on AS 1742 3 2002 b Appropriate judgement should be exercised so as to ensure the safe passage of traffic at all times Austroads 2011 Austroads Test Method AG AM T007 Pavement Deflection Measurement with a Deflectograph 6 2 a Deflection Survey Determine the exact start and end points of the survey and also the number of lanes and direction of testing If in doubt check with the client and or the contract supervisor Measure offset of outer wheelpath from kerb or lane line The lane to be surveyed is called the test lane For routine network surveys unless otherwise directed the test lane shall be the lane that is used by the majority of the traffic For most roads this coincides with the outer slow kerb lane Testing shall not be carried out where there is excessive water on the pavement or where wet conditions will affect the safety of the operation Make a visual check of all test components and check the rear tyre pressures and adjust to the standard pressure as necessary As the tyr
5. llow the precise measurement of the distance travelled during testing to an accuracy of 1 m km A guide frame attached to the steering system of the truck that will align the tips of the measuring arms of the test frame so as to allow the free passage of the passing wheels without touching the sides of the tyres A winching system to cycle the test frame forward after each measurement phase A test frame assembly of such durability dimensions and geometry that will allow sustained operation over long distances the tips of each measuring arm to pass through the corresponding set of rear dual wheels without touching the insides of the tyres the connection of the measuring arms to LVDTs of infinite resolution the entire test frame unit to have an accuracy of 30 microns at the tip Suitable instrumentation signal conditioning and a data acquisition system capable of capturing and recording deflection values for each test bowl at between 3 m and 7 m intervals The components of the system should conform to the manufacturer s specifications and be suitable for continuous use Suitable warning devices necessary for traffic control Austroads 2011 93 Austroads Test Method AG AM T007 Pavement Deflection Measurement with a Deflectograph 4 2 Other Equipment The following equipment is also required a The means of checking and maintaining a standard tyre to within 20 kPa of the manufacturer s recommended value A ty
6. on the relevant Australian Standard AS 1742 Part 3 2002 The values measured represent the deflections of a pavement as obtained with the equipment and procedures stated herein They do not necessarily agree or correlate directly with those obtained by other pavement deflection measuring methods 2 REFERENCED DOCUMENTS Austroads Test Method AG AM T008 Validation and repeatability checks for a deflectograph March 2011 International Organization for Standardization ISO 2007 International vocabulary of metrology basic and general concepts and associated terms VIM ISO IEC Guide 99 3 edn International Organization for Standardization ISO 2005 Quality management systems fundamentals and vocabulary ISO 9000 2005 Standards Australia 2009 AS 1742 3 2009 Manual of uniform traffic control devices Traffic control for works on roads Standards Australia Sydney Austroads 2011 f Austroads Test Method AG AM T007 Pavement Deflection Measurement with a Deflectograph 3 DEFINITIONS a Deflection The measured vertical elastic deformation of a pavement surface beneath the dual wheels of a standard axle load refer 4 1 b Deflection is an indication of the rate at which permanent deformation will occur under traffic over time b Deflection bowl A representation of the shape of the elastic deformation of the pavement surface caused by a load being applied to it refer Figure 3 1 Deflectographs measu
7. re pressure of 770 20 kPa 105 110 psi is typically used b Temperature gauges with a minimum range of 5 C to 100 C an accuracy of 1 C and capable of determining either ambient air and or pavement temperatures at either the surface or a depth of 30 mm below the surface c If pavement temperature is to be measured a hammer drill and tungsten bits to drill holes into the pavement structure to a depth of 30 mm A suitable oil needs to be placed in the hole to assist with pavement temperature measurement d Measuring wheel or tape to measure the offset of the device s testing wheels from the kerb or lane line to within 0 1 m e Spray paint or other suitable equipment for pavement marking f Sufficient road location information to be able to relate the data collected to the client s road referencing system g Feature sheets and a supply of media to transfer data h Deflectograph manufacturer s User Manual CALIBRATION a Calibration should be carried out in accordance with the manufacturer s User Manual Ol b Calibrations should be carried out at least every 6 months or 500 lane km of testing whichever comes first c Additional calibrations must be carried out when any test system component likely to influence measurements is replaced repaired or adjusted d An additional calibration must be carried out when damage could reasonably have been expected to have occurred such as when the m
8. re the loading bowl i e the load is moved towards the point at which the deflection is measured c Maximum deflection Do The measured maximum vertical movement of the pavement under load d Curvature Curvature Function CF Do D200 Represents the shape of the deflection bowl between the maximum deflection and the deflection at an offset of 200 mm It is used to estimate the likelihood of fatigue cracking of an asphalt pavement layer The curvature of the deflection bowl is defined by the Curvature Function CF as follows CF Do D200 where Do the maximum deflection Doo the deflection at an offset 200 mm from the point of maximum deflection A schematic view of the Curvature Function is shown in Figure 3 1 200 mm Do D200 l CF Do D200 Figure 3 1 Schematic of Curvature Function CF e Calibration ISO 1993 defines calibration as a set of operations that establish under specified conditions the relationship between values of quantities indicated by a measuring instrument or measuring system of values represented by a material measure or a reference material and the corresponding values realised by measurement standards Austroads 2011 eo Austroads Test Method AG AM T007 Pavement Deflection Measurement with a Deflectograph 4 4 1 Validation ISO 1994 defines validation as confirmation through the provision of objective evidence that requirements for a specific in
9. sed release All Richard Wix ARRB project AT1484 Substitution 2 March 2011 1 Key Format change in format Substitution old section removed and replaced with new section New insertion of new section Removed old section removed Austroads 2011 ee e
10. st files on separate media typically a working copy and a backup copy As soon as possible after returning from the field process and or archive both data copies REPORTING The data to be collected but not necessarily reported for each survey must include the following a date time of testing known test axle load to the nearest 0 1 tonne tyre pressure of the test axle tyres location of the pavement road section with regard to the client specified location reference system including start and end chainages of survey test runs and locations of any reference or control points within the survey test lane and direction of survey deflection bowls measured and the chainages at which they were measured as a minimum maximum deflection and the curvature function must be reported ambient air temperature reported to at least the nearest 1 C if measured pavement surface temperature reported to at least the nearest 1 C if measured pavement temperature at 30 mm depth reported to at least the nearest 1 C if measured error or event flags and operator comments where applicable Austroads 2011 Austroads Test Method AG AM T007 Pavement Deflection Measurement with a Deflectograph AMENDMENT RECORD Amendment No Sections amended Action Date 1 Initial release All Graham Foley Graham Foley amp Associates amp Michael Moffatt New 26 March 2007 ARRB 2 Revi
11. tended use or application have been fulfilled EQUIPMENT Vehicle Specification A deflectograph consisting of the following a A single rear axle rigid truck or similar vehicle with dual wheels fitted to allow their free passage past the test arms as they move up to them In order to be consistent with historical standards use of radial tyres of type 1200 x 20 is common practice The effects of using different tyre technologies and sizes needs to be carefully considered refer 4 1 b A ballast of a known and evenly distributed load A load of 8 2 0 15 tonne on the rear axle has been adopted as a standard to provide consistency with the Equivalent Standard Axle ESA derived from analysis of the AASHO road test data collected in the 1950s Other loads may be chosen for the following reasons if the effect of a different generally higher load level is to be assessed where it has been unavoidable to use alternative tyre technologies or sizes a Load Correction Factor is applied to allow conversion of values of deflection and curvature to those representing an 8 2 tonne load on standard tyres The capability to travel at a constant speed up to 4 km h for extended periods The capability of mounting a guide frame a winching system for the test frame and a test frame assembly with measuring arms each connected to a Linear Variable Differential Transducer LVDT A device such as a shaft encoder or a distance rotopulse to a
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