AASHTO R 41-2005 Standard Practice for Measuring Pavement Profile Using a Dipstick《用量油尺测量路面剖面》.pdf

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1、Standard Practice for Measuring Pavement Profile Using a DipstickAASHTO Designation: R 41-05 (2015)1American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-5a R 41-1 AASHTO Standard Practice for Measuring Pavement Profile

2、Using a DipstickAASHTO Designation: R 41-05 (2015)11. SCOPE 1.1. This standard practice is used to manually collect precision profile data utilizing the Face Technologies Dipstick. The dipstick measures profiles (relative elevation differences) at a rate and accuracy greater than traditional rod and

3、 level surveys. Procedures for measuring both longitudinal and transverse profiles are described. 1.2. Experienced operators have been able to obtain 500 readings per hour using this procedure. 1.3. This standard practice may involve hazardous materials, operations, and equipment. It does not purpor

4、t to address all of the safety concerns associated with its use. It is the responsibility of the user of this standard practice to consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 2. REFERENCED DOCUMENT Dipstick Man

5、ual. Face Technologies, Norfolk, Virginia. 3. TERMINOLOGY 3.1. dipstickthe dipstick is a manually operated device that houses an inclinometer and measures relative elevation differences from one foot to the other. The dipstick measurements can be recorded manually or stored in a handheld computer us

6、ing either a trigger or an automatic storage method. 4. SUMMARY OF PRACTICE 4.1. For longitudinal profile measurements, the wheelpaths are first located then cleared of any excess debris. Chalk lines are established to ensure the same path is surveyed in both directions. The dipstick is then moved a

7、long the chalk line and measurements are recorded at 0.3-m (1-ft) intervals. The dipstick is “walked” up and back along the same line, thereby allowing a closure error to be calculated. If the closure error exceeds a given amount, the recorded measurements are questionable and the survey may need to

8、 be repeated. Collected information can then be used to calculate various roughness indices such as the International Roughness Index. 4.2. Transverse dipstick measurements are conducted in a fashion similar to the longitudinal. That is, the location for the transverse measurement is established, a

9、chalk line is snapped perpendicular to the travel lane, the dipstick is walked over and back across the lane, and the closure error is calculated. Measurements are recorded at 0.3-m (1-ft) intervals and can be used to calculate rutting using various computational methods. 2016 by the American Associ

10、ation of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-5a R 41-2 AASHTO 5. SIGNIFICANCE AND USE 5.1. Longitudinal profile measurements are used during construction to assess the pavement smoothness and are often used to determine con

11、tractor pay factors. Elevation profiles, when converted to roughness measurements, are also gathered for estimating the performance of in-service pavements, which can then be utilized in a pavement management system. Increasingly, dipstick measurements are being utilized to check high-speed profilin

12、g devices. 5.2. Transverse dipstick measurements are used to develop a cross-profile of the roadway. Cross-profiles are then used to calculate rut depths along a given roadway. This method of rut depth determination can be more accurate than using a straightedge and allows rut depths to be calculate

13、d based on differing standards such as a 3.6-m (12-ft) wire line, 1.8-m (6-ft) straightedge, or 1.2-m (4-ft) straightedge. 6. EQUIPMENT 6.1. The Face Technologies DipstickA manually operated device for the collection of precision profile measurements at a rate and accuracy greater than traditional r

14、od-and-level survey procedures for individual readings. 6.1.1. The body of the dipstick houses an inclinometer (pendulum), LCD panels, and batteries for power supply. The sensor of the dipstick is mounted in such a manner that its axis and the line passing through the contact points of the footpads

15、are coplanar. The sensor becomes unbalanced as the dipstick is pivoted from one leg to the other as it is moved down the pavement, causing the display to become blank. After the sensor achieves equilibrium, the difference in elevation between the two points is displayed. 6.1.2. The dipstick is equip

16、ped with a choice of hardened-steel spike feet or ball-and-swivel footpads. The swivel pads shall be used on pavements. 6.2. The profile that is computed from dipstick measurements may have a shift from the true profile. This shift can be eliminated by applying a bias correction to distribute the cl

17、osure error. 7. DIPSTICK MAINTENANCE 7.1. MaintenanceSpecific, detailed maintenance procedures are contained in the manuals provided with each individual piece of equipment, and the operator shall become intimately familiar with the maintenance recommendations contained in all equipment manuals. 7.1

18、.1. It is not the intention of this standard practice to supersede manufacturers minimum services and service intervals, but to provide supplementary service requirements. Where there is a conflict between this guide and the manufacturers instructions, the more stringent requirements shall be follow

19、ed. 7.1.2. Routine MaintenanceRoutine maintenance includes those functions that can be easily performed by the operator with minimal disassembly of a particular device. Routine maintenance for the dipstick includes the cleaning and lubrication of the ball-and-socket joints on the footpads, replaceme

20、nt of the batteries, and cleaning of the battery contacts. These items are basic and easily performed preventive measures and shall always be completed prior to operation of the equipment. 7.1.3. Major MaintenanceMajor preventive services shall include much more than the routine checks and will requ

21、ire some disassembly of the equipment by personnel with technical capabilities beyond the skill of the operators such as the manufacturer. Items such as battery connector 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation o

22、f applicable law.TS-5a R 41-3 AASHTO replacement would fall into the major maintenance category. The appropriate service intervals are outlined in the equipment manufacturers manual. 8. DIPSTICK PREOPERATIONAL CHECKS 8.1. Check the condition of footpads and replace if necessary. Clean and lubricate

23、the ball-and-socket joints on the footpads to ensure smooth pivoting of the instrument. When the joint is dirty, pivoting becomes difficult and slippage of the footpad can occur. A cleaning agent such as WD-40 and a light oil for lubrication will work for the ball-and-socket joint. 8.2. Install a fr

24、esh set of batteries in the instrument and securely close the battery compartment. Batteries shall be changed after 4 h of usage to ensure continuity of measurements. 8.3. Check and, if necessary, retighten the handle on the instrument. 8.4. Zero Check, Manual DipstickPerform the zero check prior to

25、 and after any dipstick measurements. This test shall be performed on a smooth, clean surface where the instrument can be properly positioned (the carrying case for the dipstick or a flat board will suffice). After positioning the dipstick, draw two circles around the two footpads, and note the read

26、ing on the display (reading = R1). The instrument shall then be rotated 180 degrees, and the two footpads placed on the two circles that were drawn earlier. Note the reading obtained (reading = R2). If the readings from the two placements (R1 and R2) add up to within 0.1mm (0.003 in.), the dipstick

27、has passed the zero check. If the addition of two readings does not fall within these limits, zero adjustment is necessary. The zero adjustment shall be performed using the following procedure. 8.4.1. Obtain the average of the two dipstick readings in Equation 1: e = 0.5 (R1 + R2) (1) Then subtract

28、this value from R2 to obtain R2o in Equation 2: R2o = R2 e (2) 8.4.2. With the dipstick still in the R2 reading position, loosen the setscrew. Adjust the start end, moving the pin up or down so that the display reads R2o. Thereafter, tighten the setscrew and rotate the dipstick back to the R1 readin

29、g position and read the display (reading = R1o). Now the addition of R1o and R2o should be within tolerance. If this sum is not within tolerance, repeat the adjustment procedure until the two readings are within tolerance. 8.4.3. This zero adjustment is the only adjustment the operator is allowed to

30、 make on the dipstick. 8.5. Zero Check, Automated DipstickThis check should be performed on a smooth, clean, and stable surface (carrying case for the dipstick or a flat board will suffice) where the instrument can be properly positioned. Circles shall be drawn around the two footpads and the CAL bu

31、tton depressed once. The instrument should then be rotated 180 degrees, and the two footpads placed in the circles drawn earlier. The CAL button should again be depressed once. The display will flash “CAL” three times, after which the error is automatically stripped out of the readings. Note the rea

32、ding at switch end of dipstick. Rotate dipstick and place two footpads in the circles, and note the reading at switch end. If the two readings that were noted add up to within 0.1 mm (0.003 in.), the dipstick has passed the zero check. The zero check can be performed only once. If the check is not s

33、uccessful, the dipstick must be turned off, turned back on, and the zero check repeated. 8.6. Calibration Check, Manual and Automated DipstickCheck the calibration of the device before and after any dipstick measurements, after the zero check and zero adjustments are performed. To check the calibrat

34、ion, place the 3.2-mm (0.125-in.) calibration block under one of the dipstick footpads. The reading displayed, minus 3.2 mm (0.125 in.), should equal the previous reading plus 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violat

35、ion of applicable law.TS-5a R 41-4 AASHTO 0.1 mm (0.003 in.). If the answer is not within this tolerance, Face Technologies shall be contacted to repair the dipstick. 8.6.1. Both the zero check and calibration check shall be performed at the beginning and end of data collection. 9. CALIBRATION 9.1.

36、Dipstick CalibrationCalibration of the dipstick is fixed during manufacture and cannot be altered by the user. Factory calibration accuracy is stated to be 0.038 mm (0.0015 in.) per reading. The user can verify the calibration against a standard calibration block that is provided with the dipstick.

37、If the dipstick fails the calibration test, it shall be returned to the manufacturer for repair. 9.2. Gauge Block CalibrationThe gauge block used during the calibration check shall be calibrated to an accuracy of 3.175 0.025 mm (0.125 0.001 in.) using a local calibration laboratory or a calibration

38、micrometer to ensure the minimum 4:1 ratio of accuracy of gauge blocks to the dipstick. The gauge block shall be recalibrated once every year, or more frequently, depending on (1) presence of oxidation, (2) evidence of erosion, and (3) possible damage caused by accidental mishandling in the field. 9

39、.2.1. If the calibration block (gauge block) thickness is not within 3.175 0.025 mm (0.125 0.001 in.), all data collected since the last check of the block are suspect and may have to be disregarded. 10. SITE INSPECTION AND PREPARATION 10.1. General Pavement ConditionThe pavement shall be clear of i

40、ce, snow, and puddles of water before profile measurements can be taken with the dipstick, as such conditions can affect the profile measurements. Clean loose stones and debris from the area to be profiled to prevent slippage of the dipstick footpads during measurements. 10.2. Identify WheelpathsFor

41、 longitudinal profiles, use a chalk line to mark a straight line in each wheelpath 0.8 m (32.5 in.) from the center of the travel lane. The center of the travel lane shall be located using the following guidelines: 10.2.1. Case IWhere the wheelpaths can be easily identified, consider the center of t

42、he travel lane to be midway between the two wheelpaths. 10.2.2. Case IIWhere the wheelpaths are not clearly identifiable, but the two lane edges are well defined, consider the center of the travel lane to be midway between the two lane edges. 10.2.3. Case IIIWhere only one lane edge is well defined,

43、 consider the center of the travel lane to be 1.8 m (6 ft) from the edge. 10.2.4. A comment in the data collection sheet or field book shall be made on how the centerline of the lane was defined. This information will help to collect consistent data in future profile measurements at that location. 1

44、0.3. Identify Transverse Profile LocationsLay out and mark straight lines for transverse profile measurements. The lines shall be perpendicular to the edge of the pavement at specified testing intervals. The location of lines shall be adjusted to avoid raised pavement markings and similar anomalies.

45、 The need for and magnitude of such adjustments are to be recorded on the data sheets. 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-5a R 41-5 AASHTO 11. LONGITUDINAL PROFILE TEST PROCEDURE 11.1. T

46、o start profile measurements, the dipstick shall be placed on a marked wheelpath line at the start point with the start arrow pointing forward. A clockwise rotation is recommended because the handle can start to unscrew if you use a counterclockwise rotation. However, it is prudent to keep the same

47、motion for all measurements so that any potential errors introduced by the rotational direction are consistent in all dipstick data. 11.1.1. As the dipstick is walked along the marked wheelpath, the readings shall be recorded each time the dipstick is rotated. If a manual dipstick is used, the data

48、shall be recorded on a data sheet or in a field book; in the auto-read dipstick, the readings are stored in the computer attached to the dipstick. In this case, the operator shall use either the trigger to instruct the computer to store the reading or the automatic storage scheme in the lowest produ

49、ction rate possible. The trigger is preferred because this ensures adequate time for the pendulum to stabilize. Use of the automatic storage mode, even at the lowest production rate, may not allow adequate time for stabilization, thus introducing possible errors in the data. 11.2. Frequently, an operator will introduce bias in the readings by leaning the dipstick handle laterally from a true vertical position during operation. The operator must not apply any lateral pressure on the handle while the reading is taken. Two runs on each wheelpath of the