Evaluation of the Rolling Wheel Deflectometer (RWD) in Louisiana. John Ashley Horne Dr. Mostafa A Elseifi

Transcription

1 Evaluation of the Rolling Wheel Deflectometer (RWD) in Louisiana John Ashley Horne Dr. Mostafa A Elseifi

2 Introduction Louisiana uses the Falling-Weight Deflectometer (FWD) for project level testing Limitations of FWD at the network level: Costly and slow testing process Discrete testing of the pavement network Delays to the public due to lane closures Safety of highway workers during testing

3 Overview Overview of RWD Field testing program Present collected RWD and FWD data Comparison of RWD and FWD data 3

4 Rolling Wheel Deflectometer Test at traffic speed (up to 60mph) Measures center pavement deflection to vehicle loading Final prototype introduced in 2003 but has never been tested in Louisiana (RWD) 1/20/2011 4

5 Rolling Wheel Deflectometer Deflection- Measurement System Heating/Cooling System 53ft Steel-Loading Plates 1/20/2011 5

6 Rolling Wheel Deflectometer Data Collection Vehicle Lasers

7 Rolling Wheel Deflectometer Data Collection Vehicle Distance Measuring Instrument (DMI)

8 Rolling Wheel Deflectometer Calibration

9 Field Testing Plan Testing program was conducted over two phases: Phase I: RWD testing of the complete asphalt road network (about 1500 miles) in District 5 Phase II: Detailed RWD evaluation in District 5 16 test sites were tested using RWD FWD testing conducted within 24 hrs of RWD testing 1/20/2011 9

10 Rolling Wheel Deflectometer Phase I Network Testing UNION MOREHOUSE WEST CARROLL EAST CARROLL LINCOLN OUACHITA RICHLAND MADISON JACKSON

11 Field Testing Plan Phase II Research Sites 1/20/

12 Field Testing Plan Site ID Pavement Type Subgrade/Base Type AADT CPI (2009) Condition- CPI IRI (2009) 1 HMA Granular 1, good HMA Granular 2, good HMA Stabilized 6, very good HMA Stabilized 244 N/A very good N/A 5 HMA Stabilized 3, very good HMA Stabilized 5, very good Composite Granular 29, very good HMA Granular 6, fair HMA Stabilized 3, very good HMA Granular poor HMA Stabilized poor HMA Stabilized 1, fair HMA Stabilized 7, good Composite Granular 2, poor S. Treated Stabilized good S. Treated Stabilized poor /20/

13 Field Testing Plan - RWD Triplicate runs conducted on each site Five test speeds: 20, 30, 40, 50, and 60 mph High speed not possible on secondary roads Field testing conducted in December 2009 Temperature ranged from 29 to 68F Pavement temperature recorded during testing Deflection shifted to 68F using the BELLS method 1/20/

14 Field Testing Plan - FWD FWD testing was conducted at a spacing of 0.06 km in the middle of the averaging interval used in RWD testing. Three load levels of 40, 53, and 66 kn were used in the FWD deflection-testing program.

15 Data Processing and Filtering Laser deflection readings are measured at 15-mm intervals Irrelevant data (bridge, sharp curves, and at traffic signals) were removed Erroneous data may be obtained if pavement is wet or severely cracked 1/20/

16 Data Processing Valid deflection measurements were averaged every 0.1 mile (average of 10,728 individual readings) 30 Averaging Interval 6 Deflection, mils As averaging length decreases, deflection variability increases 528 ft 132 ft 33 ft Standard deviation of means, mils 4 2 An averaging length of 528 ft is recommended for PMS applications to reduce random error to approximately 1 mil Logmile Interval length, ft 1/20/

17 Repeatability Analysis Run 1 Run 2 Run 3 Mean Deflection (mils) Station (mile) Site 4 Newly Constructed in /20/

18 Repeatability Analysis Run 1 Run 2 Run 3 Mean Station (mile) Site 6 CPI = 99 1/20/ Deflection (mils)

19 Repeatability Analysis Deflection (mils) Run 1 Run 2 Run 3 Mean Station (mile) Site 8 CPI = 70 1/20/

20 Repeatability Analysis Run 1 Run 2 Run 3 Mean Bridge Bridge Station (mile) Site 11 CPI = 57 1/20/ Deflection (mils)

21 Coefficient of Variation (%) Repeatability Analysis COV ranged from 6 to 20% with an average of 15% Measurements were more scattered in sites in poor condition, than in sites in good conditions Site ID 1/20/

22 Effect of Testing Speed Avg. Deflection (mm) The influence of the testing speed on the measured deflection was minimal Deflections data obtained at different speeds may be comparable kph 48 kph 64 kph 80 kph 96 kph Site ID 1/20/

23 Site 1 Fair Site 2 Good Site 3 Very Good Deflection (mm) RWD FWD Station (km) 1/20/

24 1.200 Site 8 Fair Site 9 Very Good Site 10 Poor RWD FWD Station (km) 1/20/ Deflection (mm)

25 FWD vs. RWD Site ID Average FWD (mils) Average RWD (mils) Pearson Correlation P-value Decision < Not Equal < Not Equal < Not Equal < Not Equal < Not Equal < Not Equal < Not Equal < Not Equal < Not Equal Equal < Not Equal < Not Equal < Not Equal < Not Equal Not Equal < Not Equal 1/20/

26 FWD vs. RWD Average FWD Center Deflection (mils) Speed 20 mph y = e x R² = Average RWD Deflection (mils) Average FWD Center Deflection (mils) Speed 30 mph y = e x R² = Average RWD Deflection (mils) Average FWD Center Deflection (mils) Speed 40 mph y = 1.493e x R² = Average RWD Deflection (mils) Average FWD Center Deflection (mils) y = e x R² = /20/ Speed 50 mph Average RWD Deflection (mils)

27 Findings and Summary Repeatability of RWD measurements was acceptable - average COV at all test speeds of 15%. Measurements were more scattered in sites in poor condition, than in sites in good conditions The influence of the testing speed on the measured deflections was minimal 1/20/

28 Findings and Summary The scattering and uniformity of the FWD and RWD data appears to follow closely the conditions of the roadway. RWD deflection measurements were in general agreement with FWD deflections measurements The mean center deflections from RWD and FWD were statistically different for 15 of the 16 sites 1/20/

29 Questions