Smoothness Specifications for Pavements Final Report (1997) / Chapter Skim
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Appendix E: Descriptions of Smoothness-Measuring Equipment
Appendix E: Descriptions of Smoothness-Measuring Equipment
Pages 521-553
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From page 523... ...
Discussed in this appendix are the pavement smoothness measuring systems currently used for crucial construction smoothness quality control testing and listed In table E-~. Several other profile- and smoo~ness-measur~ng systems have been used for pavement management purposes, including numerous high-speed profile measuring systems.
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From page 524... ...
Although use of more sophisticated smoothness measuring equipment is the norm for use on most mainline paving projects, there are some situations in which the straightedge may be the primary method of measuring smoothness. About two~irds of the State agencies polled in 1994 indicate that straightedges are used to augment other forms of smoothness control.
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From page 525... ...
The rolling straightedge is slow and incapable of measuring "true" pavement surface profile. No record of the equipment output is provided by this system except for the paint markings on the pavements surface, but it is useful for bridge decks and small projects.
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From page 526... ...
Profilograph Equipment The term profilograph refers to a rigid frame device carried by a system of support wheels that provides a dawn from which pavement surface deviation measurements can be made. A profile wheel, which rests on the pavement surface at the center of the unit, is linked to a mechanical strip chart recorder or computer, and variations In vertical movement of the profile wheel with respect to the established datum are recorded.
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From page 527... ...
Overall pavement smoothness is expressed by this equipment in terms of its "profile index" (Pl) and a tolerance for individual bumps.
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From page 528... ...
The American Society for Testing and Materials has developed a standard method for profilograph testingASTM E 1274, "Standard Test Method for Measuring Pavement Roughness Using a Profilograph." In 1978, Me California DOT prepared their latest revision of California Test 526 "Operation of the California Profilograph and Evaluation of Profiles." The increased use of Me California-type profilograph over Me past 35 years suggests that it has filled a definite need in the area of construction smoothness control. However, there is growing concern about certain lunitations of this instrument, including the following (Scofield 1992; Scofield, Kalevela and Anderson 1992)
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From page 529... ...
Relation to User Response Because Me profilogram is known to amplify and attenuate Me true pavement surface profile, there is some concern about how well the profilograph output relates to the wavelengths of a pavement profile that are felt by highway users. Several cases have been documented in which new pavements that received low PI ratings, and in some cases incentive payments, were found by the roadway users to be uncomfortably rough.
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From page 530... ...
Figure E-2. James Cox & Sons, Inc.
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From page 531... ...
Figure E-3. IPMC McCracken computerized profilograph.
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From page 532... ...
The system operates using a laptop computer In conjunction with Microsoft Windows software. Measured profile data can be stored digitally and plowed on a conventional printer.
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From page 533... ...
A 1985 study of five repeat runs at one PCC site and two AC test sites indicated that the repeatability of the manually-reduced Rainhart system is fair with an average coefficient of variation of 6.1 percent (Kulakowski and Wambold 1989~. This relates to a standard deviation of 0.4 in/ml (6.3 mm/km)
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From page 534... ...
- ~ - - - - ~ - ~ i' Figure E-5. ProScan elec~Tomc trace reduction system.
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From page 535... ...
Both automobiles and standardized trailers have been used for this purpose, win measurements taken of Me vertical movement of the rear axle of Me automobile or of the axle of Me trailer win respect to the vehicle frame. Primarily, RTRRMS are used for data collection on highway networks for pavement management purposes; however, they have been used on ia limited basis for controlling smoothness of new pavement construction.
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From page 536... ...
This results in concern for the accuracy and repeatability of MRM systems when used in initial pavement smoothness testing and control. Gillespie, Sayers, and Segal concluded in 1980 that "in Me more critical functions of evaluating sections of individual roads (especially Me relatively smooth surfaces represented by new construction)
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From page 537... ...
The company's literature lists two models, MDR 4010, Mays Roughness and Highway Features Inventory System, and MDR 2010, Mays Roughness and Highway Features Inventory System Using Lap-Top Computer. BPR Roughomeler The BPR Roughometer was first Introduced in 1925, and was recognized as being the best high-speed smoothness measuring device available at that time (Buchanan E-15
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From page 538... ...
This device measures the number and amplitude of vertical deviations between the body of a standard automobile and Me center of the rear-axIe housing. It was primarily used with pavement rating systems into the early 19SOs and, to a limited degree, as part of smoothness specifications.
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From page 539... ...
Although it has had limited use for construction smoothness control, this device is used for pavement management system surveys because of its accuracy and rapid rate of data collection. in addition, it is currently being used to collect profile measurements on me pavement test sections included in Me FHWA's Long Term Pavement Performance (LTPP)
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From page 540... ...
sensors are available for transverse profile measurement. Pavement profile elevations are taken at An (25.4 nun)
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From page 541... ...
The LISA measures profile by the GM concept at a far lower cost than the van-based unit and, because of its light weight, permits analysis of concrete pavements within hours after paving. An accelerometer and a vertical distance sensor are used to measure changes In pavement elevation on any pavement type.
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From page 542... ...
The output is RMSA (roof mean square acceleration) roughness and correlation equations are used to provide several response-type roughness Indices, such as the Mays Ride Number, Me PCA Roadmeter number, and the BPR Roughometer index.
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From page 543... ...
minimum recording interval. MDR 4087 Enhanced Profile/Rut depth/Roughness System, shown in figure E9, featuring profile/IRI in two wheelpaths; average or half-car simulation IRI; average rut depth In each wheelpath; two inertial reference accelerometers; five or more height sensors one linear distance sensor, and a minimum recording interval of 3 in (76 mm)
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From page 544... ...
A single wheelpath portable laser profiler is also available for $45,000. Dynatest Profiling System In 1995, Dynatest introduced a fully-automated roughness measurement test system called the Model 5051 RSP (Road Surface Profiler)
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From page 545... ...
The menu-driven software leads the operator through system calibration, component checks, and data collection. Data can Men be analyzed and presented graphically and numerically.
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From page 546... ...
The ARRB Walking Profiler was developed and manufactured by We Australian Road Research Board and is marketed In the United States by Trigg Industries International, Inc. for pavements, building slabs, and game courts as a World Bank Class ~ profile measuring device.
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From page 547... ...
Figure E-ll. Infrastructure Management Services Laser RST profiler.
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From page 548... ...
is a precision smoothness measuring device, operated by hand. Its shape is somewhat similar to a walking cane with a I-ft (0.3 m)
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From page 549... ...
Class ~ profiling instruments are assumed to provide absolute elevation relative to true horizontal profile with less than I.5 percent bias. In highway applications, the Face Dipstick is used primarily to calibrate other types of smoothness measuring equipment and is also used to evaluate the smoothness of warehouse floors when smoothness is a critical factor In automated storage/retrieval operations.
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From page 550... ...
Other Profile and Smoothness Measuring Systems In addition to the above described pavement smoothness measuring devices, several other devices have been used for smoothness evaluations. These Include the ChIoe slope variance measuring system, Me Siometer accelerometer-based system, the Transportation Road Research Laboratory (TRRL)
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From page 551... ...
This trueness to the actual slope profile is a positive advantage of the CHLOE system; however, the SV statistic is derived from an band of profile wave numbers much broader than is significant to an automotive vehicle, and as a result introduces a random error that degrades the agreement between RTRRM system output and SV (Gillespie, Sayers, and Segal 1980~. Walker Siomeler The Siometer accelerometer response device was developed at We University of Texas in the 1980s (Walker and Phung 1987~.
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From page 552... ...
Faster data collection systems, unproved data storage hardware, higher-speed computing capabilities, and better height sensing mechanisms should make it more possible to measure and evaluate megatexture (noise source) and microtexture (friction source)
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From page 553... ...
accurately measure these wavelengths. Of course, other uses can be made of the new information made available by technological advances, including friction and noise evaluations, and highway agencies will use these advances to maintain high quality pavements In an era of shrinking budgets.
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