Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: During the reporting period a new task order was issued by FHWA. It provides the basis for on going technical support of all FWD calibration centers. Outputs included renewing the operator certification at the Texas, Colorado, and Minnesota DOT calibration centers; training and certification at the Pennsylvania and Indiana DOT calibration centers; and installation and training for a new calibration center operated by Montana DOT. We began the development and evaluation of a new, high-capacity reference load cell for use in calibration. This task was not complete by the end of the reporting period. One additional task was to create a 10-minute video that explained the benefits of calibrating an FWD. Filming on this project began at the Pennsylvania DOT calibration center a few days before the end of the reporting period. PARTICIPANTS: Certification was provided to the state Departments of Transportation in Pennsylvania, Minnesota, Colorado, Texas, and Indiana. TARGET AUDIENCES: Target audiences include state departments of transportation, FWD manufacturers, and FWD equipment owners. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
As reported at the September 2008 meeting of the FWD Users Group in Colorado Springs, CO, about 130 FWDs were calibrated during the period October 2007 through September 2008. Calibration will improve their accuracy and enhance the precision of the pavement rehabilitation designs based on their data.
Publications
- No publications reported this period
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Progress 10/01/06 to 09/30/07
Outputs
OUTPUTS: The products of this research were output to a series of FWD Calibration Centers. The method used was to create a three-day program of training during which the new calibration equipment was installed. The training program was conducted on site at each of the four regional calibration centers that are sponsored by the Federal Highway Administration (FHWA) and run by the state Departments of Transportation (DOT). The three-day Installation-Training Program was conducted in the offices of Colorado DOT in Denver, Colo., Minnesota DOT in Maplewood, MN, Texas A&M University in Bryan, TX, and Pennslyvania DOT in Harrisburg, PA. Texas A&M runs a calibration center under contract from Texas DOT. In addition the three-day program was conducted on site for three FWD manufacturers. These included Dynatest PSC, Inc. in Starke, FL, Foundation Mechanics, Inc. in El Segundo, CA, and Grontmij/CarlBro A/S in Kolding, Denmark. The three-day program was also conducted on site at the State of
Western Australia Main Roads Department in Perth, Australia. At all locations either Professor Irwin or Senior Engineer David Orr, or both, conducted the training.
PARTICIPANTS: Training was provided to the state Departments of Transportation in Pennsylvania, Minnesota, Colorado, Texas, and Western Australia. Training was also provided to industrial manufacturing organizations in California, Florida, and Denmark.
TARGET AUDIENCES: Target audiences include state departments of transportation, FWD manufacturers, and FWD equipment owners.
Impacts
This project has completely changed the way that falling weight deflectometers are calibrated. The use of a mems accelerometer has revolutionized the calibration process. New software has been written that provides extensive data checks leading to quality assurance. Overall the procedure has become more portable, and it is no longer required to have a test pad of specific properties on which to conduct the calibrations. The process has been speeded up to the extent that what used to take six to eight hours to accomplish can now be done in less than two hours. The research showed that the accuracy of the calibration factors under the new procedure is the same or better than what was achieved with the old procedure.
Publications
- Orr, D.P., Irwin, L.H. and Atkins, D. 2007. FWD Calibration Center and Operational Improvements: Final Report. Cornell Local Roads Program, Cornell University, Ithaca, NY. 171 pp.
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Progress 01/01/05 to 12/31/05
Outputs
During 2005 the Cornell Local Roads Program selected new hardware for use in data acquisition. Progress was made in converting the old software and developing new software to use with the new hardware. About triggering of the new hardware was accomplished. We selected a Silicon Designs 2220 MEMS accelerometer to use as a replacement for the reference LVDT in the calibration procedure. We developed a method for digital double integration of the acceleration signal to obtain displacement and demonstrated its accuracy. We investigated a platter design as a sensor holder, and found that it would not work because there is too much rotation due to ground movement. During the coming year we will study other designs for the sensor holder, and then finalize the new calibration procedures.
Impacts
This project will provide new equipment and revised methods for calibration of falling weight deflectometers (FWDs). This will expedite the calibration and result in more widespread use of calibration by FWD owners. Calibrated FWDs give better and more accurate projections of the remaining life and structural improvement needs of highway pavements. The overall impact of these improvements is lower road user costs.
Publications
- Irwin, L.H. and Richter, C.A. 2005. History and Development of U.S. Procedures for FWD Calibration, TRB 05-2334, National Academies of Science and Engineering, National Research Council, Transportation Research Board, Washington, D.C.
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