AASHTO R 40-2010 Standard Practice for Measuring Pavement Profile Using a Rod and Level.pdf

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1、Standard Practice for Measuring Pavement Profile Using a Rod and Level AASHTO Designation: R 40-10 (2013)1,2American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-5a R 40-1 AASHTO Standard Practice for Measuring Pavement

2、Profile Using a Rod and Level AASHTO Designation: R 40-10 (2013)1,21. SCOPE 1.1. The rod and level can be used to accurately measure the profile of a pavement. The profile data can be used to evaluate the roughness of the pavement by computing a roughness index such as the International Roughness In

3、dex (IRI) or to evaluate effects such as frost heave or swelling of soils. In computing roughness indices, only the relative elevations and not the absolute elevations are needed. The guidelines in this standard practice can be applied to conventional survey equipment such as an optical level and gr

4、aduated staff, which require the readings to be manually recorded, as well as automated equipment that is capable of automatically storing the measured data. 1.2. This standard practice may involve hazardous materials, operations, and equipment. It does not purport to address all of the safety conce

5、rns 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 2.1. ASTM Standard: E1364, Standard Test Method

6、for Measuring Road Roughness by Static Level Method 3. SUMMARY OF METHOD 3.1. To measure the pavement profile using the rod and level, two persons are generally needed. One person is needed to hold the rod (rod person) and another to operate the level and take readings (instrument operator). If the

7、level is not capable of automatically recording the readings, an additional person (record keeper) to record the readings will make the process quicker. An experienced crew of three would require fewer than 10 s to obtain one reading. This involves the positioning of the rod by the rod person, readi

8、ng the level by the instrument operator, and recording the measurements by the record keeper. 3.2. Relative elevations are measured along the roadway at prescribed intervals. A rod is set on the roadway, and the rod reading is recorded. 3.3. Rod readings are then converted to either a true elevation

9、 or a reference elevation from which profile statistics are then computed. 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-5a R 40-2 AASHTO 4. SIGNIFICANCE AND USE 4.1. Longitudinal profile measureme

10、nts are used during construction to assess the smoothness of new pavement. Elevation profiles, when converted to roughness measurements, are also gathered for estimating the performance of in-service pavements, and can then be utilized in a pavement management system. 5. APPARATUS 5.1. The rod and l

11、evel used in routine surveying and road construction generally will not have the resolution needed for pavement profile measurements. For pavement profile measurements, precision leveling instruments are required. The instrument used for profile measurement shall satisfy the resolution criteria note

12、d in ASTM E1364, Table 1. 5.2. The rod used shall be equipped with a bubble level so that it can be held vertical accurately. A suitable base shall be selected for the rod in order to reduce the sensitivity to small variations in rod placement. For smooth-textured pavements, any type of base is suit

13、able. For textured surfaces, a circular pad with a diameter of at least 2.0 cm (0.8 in.) is recommended. As only relative elevations are required for computing roughness indices, no correction is required for attaching a pad to the bottom of the rod. Note 1It is recommended that an invar rod be used

14、 to minimize the effects of temperature changes. This is particularly important for Class 1 surveys on smooth roads, for which the resolution requirements given in ASTM E1364, Table 1 are more stringent. 6. EQUIPMENT MAINTENANCE, ADJUSTMENT, AND VERIFICATION 6.1. MaintenanceUse shockproof packaging

15、when transporting the instrument. Clean the instrument after completing a profile measurement. Before cleaning the lenses, blow the dust off the lenses. Clean the lenses using a soft cloth. Do not touch the lenses with the fingers. If the instrument becomes wet in the field, dry it completely before

16、 packing. Inspect the tripod regularly to ensure that the connections are not loose. 6.2. AdjustmentThe user manual for the level shall be consulted on how to perform adjustments of the instrument. Different makes and models of levels will require different adjustments to be performed. The following

17、 are some common adjustments that are required in levels in order to obtain accurate measurements. The user manual for the level shall be consulted to determine whether the following adjustments are needed for the level being used and, if so, how to perform the specific adjustment. 6.2.1. Make Axis

18、of Level Bubble Perpendicular to Vertical AxisAfter setting up the level, center the bubble. Move the telescope 180 degrees about the vertical axis. If the bubble moves, the instrument needs adjustment. 6.2.2. Adjust Horizontal CrosshairsThis adjustment will ensure that the horizontal crosshairs are

19、 truly horizontal when the instrument is leveled. 6.2.3. Adjust Line of SightThis adjustment will make the axis of sight perpendicular to the vertical axis and parallel to the axis of the level. The method of adjustment for this error is commonly referred to as the two-peg method. 6.3. VerificationV

20、erify the accuracy of the markings on the rod using a standardized tape. 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-5a R 40-3 AASHTO 7. SITE INSPECTION AND PREPARATION 7.1. Identify the two whee

21、lpaths in the lane to be profiled. 7.2. Clean loose stones and debris from both wheelpaths to prevent slippage of the rod during measurements. 7.3. Locate the center of the travel lane using the following guidelines: 7.3.1. Case IWhere the wheelpaths can be easily identified, consider the center of

22、the travel lane to be midway between the two wheelpaths. 7.3.2. 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. 7.3.3. Case IIIWhere only one lane edge is well defined,

23、consider the center of the travel lane to be 1.8 m (6 ft) from the edge. 7.4. Use a chalk line to mark a straight line in each wheelpath. Position the line 0.8 m (32.5 in.) from the center of the travel lane. 7.5. Record the method used to locate the wheelpaths in the comment field of the data colle

24、ction form or logbook. This will help in locating the wheelpaths used for profile measurements at a future date. 7.6. The measurement of pavement profiles using the rod and level is labor intensive and time-consuming. Measurements will be taken along the wheelpaths at typical intervals of 70 mm (2.7

25、5 in.). Measurement accuracy must be verified at regular intervals by establishing a set of control points along the wheelpath; for example, at 30.5-m (100-ft) intervals starting from the beginning of the section. Determine the locations at which readings are to be taken, including control points, u

26、sing one of the following methods: 7.6.1. Lay a surveyors tape along the chalk line and mark distances on the pavement at 70-mm (2.75-in.) intervals using a suitable marker. Make markings along the entire length of the section on both wheelpaths. 7.6.2. Place a surveyors tape on the wheelpath with t

27、he zero of the tape corresponding to the start of the section. Secure both ends of the tape with a weight or adhesive tape. Reference distances along the section from the tape. 8. LONGITUDINAL PROFILE MEASUREMENT 8.1. Record the required information in the data collection form or logbook. 8.2. Set u

28、p the level at a suitable location, taking into account the range of the level. With some instruments, it might be possible to cover the entire test length from one instrument setup located near the center of the test section. Place the level where it will not be disturbed by passing traffic and whe

29、re it will not settle. When setting the tripod, set it as low as practical to reduce the error caused by the rod not being exactly vertical. Thereafter, level the instrument using the leveling screws. 8.3. The rod person shall place the rod at the zero position of the section and use the bubble leve

30、l attached to the rod to hold the rod vertical. When the rod is vertical, the rod person shall signal to the instrument operator to take a reading. If the readings are recorded manually by a third crew 2016 by the American Association of State Highway and Transportation Officials. All rights reserve

31、d. Duplication is a violation of applicable law.TS-5a R 40-4 AASHTO member, the instrument operator shall call out the reading to the record keeper, who shall record it on a form or in the logbook. If an automated system is used, the instrument operator shall make sure that the reading is saved. 8.3

32、.1. The rod person shall place the rod 70 mm (2.75 in.) away from the initial reading, and a new reading shall be recorded. This process shall be continued until either the entire test section is surveyed, the next control point is reached, or the horizontal range or the vertical range of the level

33、is exceeded. Relocate the level whenever the vertical or horizontal range is exceeded. Note 2The horizontal range of the level is exceeded if the distance between the level and the rod is too short or too long to focus properly. The vertical range of the level is exceeded if the rod cannot be read d

34、ue to the slope of the road. 8.3.2. After taking measurements for a distance of 30.5 m (100 ft), place the rod at the previous control point and repeat the measurement at that point. The readings must agree within the resolution of the instrument. If the readings do not agree, take new readings for

35、the length of pavement between the control points. 8.3.3. Use this procedure even if the level is not relocated between the two control points being considered. If the level is relocated between two control points, apply the same procedure, treating the pivot point (Section 8.5) as a control point.

36、8.4. When the level requires relocation, mark the location at which the rod was held for the last reading. This position is called a pivot point. Place the rod at the location where the first reading was taken with the current setup of the level and take a reading. Compare this reading with the firs

37、t reading that was taken at this location. 8.4.1. If the readings do not agree within the required resolution of the instrument as determined in Section 5.1, repeat all readings taken from the current position of the level. 8.4.2. If the readings agree, place the rod on the pivot point and record th

38、e last reading from the current setup of the instrument (foresight) and relocate the level. Place the rod at the pivot point and take a reading (backsight). Continue the measuring process as described in Section 8.3 at intervals of 70 mm (2.75 in.). If the level must be repositioned, follow the proc

39、edure described in Section 8.5. Note 3The first reading taken after the level is set up is referred to as a backsight, while the last reading taken at that setup before the level is moved is referred to as a foresight. Other readings taken between a backsight and a foresight are referred to as inter

40、mediate sights. 8.5. At the end of the test section, if the entire survey is performed from one level position, place the rod at the zero position (the point from which the survey began) and take a reading. This reading must agree with the first reading taken at this location at the start of the sur

41、vey within the resolution of the instrument. If the readings do not agree, repeat all profile measurements. 8.6. At the end of the test section, if the level was repositioned during the survey, place the rod at the last pivot point and take a reading. This reading must agree with the previous readin

42、g taken at the same position within the resolution of the instrument. If it does not agree, repeat the profile measurements from the last pivot point to the end of the section. 9. INTERFERENCES 9.1. If the level is sensitive to temperature variations, cover it with an umbrella to protect it from dir

43、ect sunlight. 9.2. Avoid making measurements during windy conditions. Movement of the level could occur. 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-5a R 40-5 AASHTO 9.3. If the level has to be s

44、et up at more than one position during profile measurements, make the length to backsights and foresights equal. This will eliminate errors due to curvature and refraction at turning points. 9.4. If the line of sight is set too close to the layer of air above the ground, significant refraction can o

45、ccur under certain atmospheric conditions. 10. CALCULATIONS 10.1. During field profile measurements, the crew is expected to record only the readings of the level using the procedures described in Section 8. The computation of the elevation profile from this data will be done in the office in the fo

46、llowing manner: 10.1.1. For profile computations, the elevation of the location where the first reading (first backsight) was measured is needed. However, as only relative elevations are needed to compute roughness indices (such as IRI), an arbitrary value can be selected for the elevation of this p

47、oint. Obtain the relative elevation of any point measured from the initial instrument setup using the following equations: instrument height (IS) = BM + RR1(1) relative elevation of a point = IS RR (2) where: IS = initial instrument height; BM = elevation of point where the first backsight was taken

48、 (assume any value; e.g., 10 m 32.8 ft); RR1= rod reading at first backsight; and RR = rod reading at any point from the initial instrument setup. 10.1.2. Once the position of the level is changed, the instrument height will also change. Obtain the new instrument height using the following equation:

49、 Nht Oht BS FS= + (3) where: Nht = new instrument height; Oht = old instrument height; BS = backsight at pivot point with the instrument at new setup location; and FS = foresight at pivot point with the instrument at the previous setup. 10.1.3. Relative elevation of points measured from a new instrument location can be determined by using Equation 2 and substituting the new instrument height for the initial instrument height. 11. QUALITY CONTROL 11.1. Field Quality ControlField quality control measurements shall be made to ensure that the level has not moved in th