LongTerm Pavement Performance Program Falling Weight Deflectometer FWD

Long-Term Pavement Performance Program Falling Weight Deflectometer (FWD) Calibration Procedures A 1 Product Line

PRESENTATION OBJECTIVES What is the FWD Product Line? n n n 2 Why FWD Calibration is Important Development of the FWD Calibration Products Get to Know the FWD Calibration Centers Understanding FWD Calibration: The FWD Video Who Should Use the LTPP FWD Calibration Products How to Get More Information on the FWD Calibration Products

FWD Calibration Product Line n n n 3 THE CENTERS u LTPP FWD Calibration Centers u Calibration Center Certification Program THE CALIBRATION PROCEDURES u Reference Calibration Procedure u FWDREFCL Software u Relative Calibration Procedure u FWDCAL Software THE VIDEOTAPE u Videotape – Working with your FWD Calibration Center to Produce Quality Deflection Data

FWD Calibration Videotape What: Capabilities: Who Should Use: 4 15 minute videotape titled “Working With Your FWD Calibration Center” Addresses key questions about FWD calibration Provides step by step guide FWD operators

FWD Calibration Videotape: Features n Step by step guide on u Reference Calibration « u Procedure to check an FWD against an independent reference traceable to NIST benchmarks. This procedure can only be done at properly equipped calibration centers. Relative Calibration Analyzes if FWD’s sensors are providing consistent data. « Verifies the integrity of the sensors. « 5

PRESENTATION OBJECTIVES n What is the FWD Product Line Why FWD Calibration is Important? n n n 6 Development of the FWD Calibration Products Get to Know the FWD Calibration Centers Understand FWD Calibration: The FWD Video Who Should Use the LTPP FWD Calibration Products How to Get More Information on the FWD Calibration Products

What is a FWD? n n 7 Comprised of a tow vehicle and trailer or self-contained in one vehicle Designed to impart a dynamic load to a pavement structure Measures deflection of the pavement surface Simulates a moving wheel load

What is a FWD Used For? n n n 8 Structural capacity/remaining life estimates Load transfer efficiency between PCC pavement joints Void detection in PCC pavements Network level pavement management Project level pavement investigations Many research applications

Why Calibrate a FWD? n n n 9 FWD is a complex system that contains electrical, hydraulic and mechanical systems to operate machine and collect data Standards needed to ensure consistency between FWD units Bad data = High cost (economic and political)

FWD Deflection Measurements Think of FWD deflections as shots at a target Uncalibrated Sensors May or may not fall within 2% May or may not be biased 10

FWD Deflection Measurements Think of FWD deflections as shots at a target After Reference Calibration Randomly scattered closer to target 11

FWD Deflection Measurements Think of FWD deflections as shots at a target After Relative Calibration Very close to intended target 12

Purpose of FWD Calibration n n 13 Purpose - benchmark of FWD unit to known, or reference, standards Reference standards are NIST traceable where applicable Procedure completed in one day (assuming no problems) Reference calibration must be performed at certified FWD calibration center

Benefits of FWD Calibration n n Procedure necessary for all FWD users Organizations performing FWD testing u u n n 14 State DOT’s Other Government entities Consultants Academia Organizations contracting for FWD services Organizations using FWD data

PRESENTATION OBJECTIVES n n What is the FWD Product Line Why FWD Calibration is Important Development of the FWD Calibration Products n n 15 Get to Know the FWD Calibration Centers Understand FWD Calibration: The FWD Video Who Should Use the LTPP FWD Calibration Products How to Get More Information on the FWD Calibration Products

Product Development Background n n 16 1987 - Strategic Highway Research Program (SHRP) selects FWDs 1988 – Original FWDs procured and “thump-off” conducted, need for calibration centers established 1989 – Calibration procedures developed 1989 – Host agencies for calibration centers solicited

Product Development Background n n n 17 1989 – FWD testing begins 1991 – LTPP Calibration Centers established 1992 - FHWA assumes leadership of LTPP 1998 – FWD Calibration Video developed To date – many, many reference/relative calibrations performed at LTPP Calibration Centers

PRESENTATION OBJECTIVES n n n What is the FWD Product Line Why FWD Calibration is Important Development of the FWD Calibration Products Get to Know the FWD Calibration Centers n n n 18 Understand FWD Calibration: The FWD Video Who Should Use the LTPP FWD Calibration Products How to Get More Information on the FWD Calibration Products

Calibration Center Locations n Four LTPP sponsored – State owned and 1999 LTPP certified u u n Non-LTPP u u u 19 Minneapolis, MN - North Central Region Reno, NV - Western Region Harrisburg, PA - North Atlantic Region College Station, TX - Southern Region Kansas State University (Kansas DOT) Purdue University (Indiana DOT) Dynatest (manufacturer)

Calibration Center Locations n Other Australia (ARRB) u South Africa u n Shown Some Interest South America u Middle East u 20

Calibration Center Certification n 21 Independent auditors inspect facilities and personnel LTPP centers are required to be certified once per year Other centers - recommended certification once per year

Calibration Center Purpose u u 22 Primarily designed to calibrate LTPP FWD equipment (dynamic impulse devices) Have successfully calibrated Dynatest, JILS, and KUAB equipment

Certification of Calibration Centers 1. 2. 3. 4. 5. 6. 23 Review facility Review reference load cell calibration procedures Review reference geophone calibration procedures Review relative geophone calibration procedures Review of documentation and protocols in place Load cell, load cell cable and vishay meter calibrated within one year

Calibration Centers: Certification Ratings n n n 24 Fully Compliant: complete compliance with FHWA LTPP procedures/directives Compliant - minor changes required: substantial compliance, a few non-critical items not performed or not performed properly Non Compliant – major changes required: one or more critical items not performed or not performed properly

Calibration Center Contacts 25 SOUTHERN REGION Mr. Doug Chalman Texas DOT 37 th & Jackson, Building 8 Austin, Texas 78731 Phone: 512 -465 -7653 Fax: 512 -465 -3681 E-mail: chalman@mailgw. dot. state. tx. us NORTH CENTRAL REGION Mr. Dave Bullock Minnesota DOT Materials and Research Lab. 1400 Gervals Avenue Maplewood, MN 55109 Phone: 651 -779 -5542 Fax: 651 -779 -5535 E-mail: dave. bullock@dot. state. mn. us WESTERN REGION Ms. Pat Polish 310 Galletti Way Sparks, NV 89431 Phone: 702 -687 -5173 Fax: 702 -687 -4846 E-mail: ppolish@dot. state. nv. us NORTH ATLANTIC REGION Mr. Tom Leitzel Pennsylvania DOT 905 Elmerton Ave. Harrisburg, PA 17120 Phone: 717 -783 -6857 Fax: 717 -783 -6013

PRESENTATION OBJECTIVES n n What is the FWD Product Line Why FWD Calibration is Important Development of the FWD Calibration Products Get to Know the Calibration Centers Understand FWD Calibration: The FWD Video n n 26 Who Should Use the LTPP FWD Calibration Products How to Get More Information on the FWD Calibration Products

PRESENTATION OBJECTIVES n n n What is the FWD Product Line Why FWD Calibration is Important Development of the FWD Calibration Products Get to Know the Calibration Centers Understand FWD Calibration: The FWD Video Who Should Use the LTPP FWD Calibration Products n 27 How to Get More Information on the FWD Calibration Products

Who Should Use the FWD Product Line n Organizations performing FWD testing u u n Organizations contracting for FWD services u 28 State and Provincial DOT’s Other Government entities Consultants Academia Should be a part of contract to have FWD reference calibrated within 1 year, relative calibrated prior to job

When To Use the FWD Product Line n General u u u n Other recommendations u u 29 Reference – Once per year Relative – After reference and once per month thereafter After a period of inactivity When taking delivery of a new FWD unit When equipment is replaced When equipment is suspect Whenever a major malfunction occurs

Uncover and Avoid Problems n Lack of Operator Training Showed up without software u No spare parts u Could not operate FWD u n Mechanical FWD not operable u Load cell badly damaged u Deflection sensors missing or damaged u 30

Benefits of Use n n n 31 Provides guidelines for calibration of testing equipment Provides a benchmark performance standard for equipment Minimizes equipment variability Promotes greater confidence in FWD testing and resulting pavement design Minimizes risk of errant pavement rehabilitation designs

Current Status of Product n n n Calibration procedures established Calibration software developed Calibration centers established Many FWDs calibrated using procedure Video produced u 32 Cooperation of MNDOT, NVDOT, FWD manufacturers

PRESENTATION OBJECTIVES n n n What is the FWD Product Line Why FWD Calibration is Important Development of the FWD Calibration Products Get to Know the Calibration Centers Understand FWD Calibration: The FWD Video Who Should Use the LTPP FWD Calibration Product Line How to Get More Information on the FWD Calibration Products 33

Get and Use the FWD Product Line n Download procedure manuals from u LTPP homepage at www. tfhrc. gov n Order procedure manuals/video: u Through LTPP homepage u Through LTPP customer service « n 34 (Tel Number: 865 -481 -2967 ) Contacts u Kathy Petros or Keith Herbold