CC8 Phase 2 Overlay Traffic Test

The National Airport Pavement Test Vehicle (NAPTV) in the NAPTF is a rail-based test vehicle capable of simulating an aircraft weighing up to 1.3 million pounds. The NAPTV consists of two carriages, a north carriage and a south carriage, each that can accommodate up to five load modules. Each load module can support two wheels, allowing for configurations of up to 20 wheels. The NAPTV can apply loads of up to 75,000 pounds per wheel and simulates aircraft wander by varying the lateral position of the carriages.

 

For more information on the Phase 2 Overlay Traffic Test click on the links in the table below. 

To be directed to the CC8 Phase 2 Overlay Comprehensive Test Plan, click here.

 

 

Gear Configuration

For the Phase 2 Overlay Test a two gear configurations were used, a triple dual tandem (3D) and twin dual tandem (2D). The dimensions of the load configuration are illustrated in the figure below. The triple dual spacing was 54 inches and the twin dual tandem spacing was 54 inches.

 


CC8 Phase 2 Overlay Gear Configuration (Click to Zoom)

Pre Trafficking

Prior to full scale trafficking on the Phase 2 Overlay section a seating load was performed using a two wheel (dual) gear at 10,000 lbs. per wheel. During the seating load the slab was monitored for vertical movement using vertical deflection sensors.


Following the seating load, a ramp-up response test was conducted with a full wander pattern. The ramp-up test was performed to ensure all systems were operating properly. The ramp-up was also utilized to determine the final decision about the wheel load to be used for full scale trafficking. A 3D gear was used for the north test item and a 2D gear was used for the south test item.

Full Scale Trafficking

Full scale trafficking of the Phase 2 Overlay Test was conducted and the dates, vehicle configurations, wheel loads, and loading passing for each stage of trafficking are summarized in the table below. Trafficking was performed at 2.5 mph with a nominal tire pressure for all load levels was 220 psi.

Day No

Date

Number of Passes

Number of Wanders

Cumulative Passes (North)

Cumulative Passes (South)

1

10/10/2017

660

10

660

660

2

10/11/2017

660

10

1320

1320

3

10/12/2017

660

10

1980

1980

4

10/16/2017

660

10

2640

2640

5

10/17/2017

660

10

3300

3300

6

10/18/2017

660

10

3960

3960

7

10/19/2017

660

10

4620

4620

8

10/23/2017

660

10

5280

5280

9

10/24/2017

660

10

5940

5940

10

10/25/2017

660

10

6600

6600

11

10/26/2017

660

10

7260

7260

12

10/30/2017

660

10

7920

7920

13

10/31/2017

660

10

8580

8580

14

11/1/2017

660

10

9240

9240

15

11/2/2017

660

10

9900

9900

16

11/6/2017

660

10

10560

10560

17

11/7/2017

660

10

11220

11220

18

11/8/2017

660

10

11880

11880

19

11/9/2017

330

5

12210

12210

20

11/13/2017

660

10

12870

12870

21

11/14/2017

660

10

13530

13530

22

11/15/2017

660

10

14190

14190

23

11/16/2017

660

10

14850

14850

24

11/20/2017

410

6.2

15260

15260

25

11/21/2017

250

3.8

15510

15510

26

11/27/2017

660

10

16170

16170

27

11/28/2017

660

10

16830

16830

28

11/29/2017

660

10

17490

17490

29

11/30/2017

660

10

18150

18150

30

12/4/2017

660

10

18810

18810

31

12/5/2017

660

10

19470

19470

32

12/6/2017

660

10

20130

20130

33

12/7/2017

660

10

20790

20790

34

12/11/2017

660

10

21450

21450

35

12/12/2017

660

10

22110

22110

36

12/13/2017

660

10

22770

22770

37

12/14/2017

528

8

23298

23298

38

12/18/2017

660

10

23958

23958

39

12/19/2017

660

10

24618

24618

40

12/20/2017

500

7.6

25118

25118

41

12/21/2017

490

7.4

25608

25608

42

12/26/2018

275

4.2

25883

25883

43

1/2/2018

385

5.8

26268

26268

44

1/3/2018

660

10

26928

26928

45

1/8/2018

462

7

27390

27390

46

1/9/2018

660

10

28050

28050

47

1/10/2018

660

10

28710

28710

48

1/11/2018

660

10

29370

29370

49

1/16/2018

660

10

30030

50

1/17/2018

660

10

30690

51

1/18/2018

660

10

31350

52

1/22/2018

660

10

32010

53

1/23/2018

660

10

32670

54

1/24/2018

660

10

33330

55

1/25/2018

660

10

33990

56

1/26/2018

660

10

34650

57

1/29/2018

660

10

35310

58

1/30/2018

660

10

35970

59

1/31/2018

660

10

36630

60

2/1/2018

660

10

37290

 

Wander Pattern

The Phase 2 Overlay Test wander pattern and positions is illustrated in the figure below. The wander pattern used for the Phase 2 Overlay Test consisted of 66 vehicle passes, with each passage of the NAPTV to the east being counted as a pass, and the return to the west counting as a second pass.


The 66 passes were arranged in 9 wander positions. Offsets from the centerline are provided in feet. The offset dimensions refer to the distance to the center of the load module, which is midway between the tires. The figure below should be used in reference to the track numbers given in the database.


Carriage Positions for each Track

Track No.

Carriage Centerline Location, ft.

North

South

-4

-18.662

11.838

-3

-17.809

12.691

-2

-16.956

13.544

-1

-16.103

14.397

0

-15.250

15.250

1

-14.397

16.103

2

-13.544

16.956

3

-12.691

17.809

4

-11.838

18.662

 


CC8 Phase 2 Overlay Wander Pattern (Click to Zoom)

 

To download the complete wander table used for the Phase 2 Overlay Traffic Test, click here.


Pavement Monitoring

During the full scale trafficking of the Phase 2 Overlay section static and dynamic responses were monitored for both gauge failure and environmental changes. In addition, the overall pavement condition was monitored using a manual distress survey and SCI calculation. HWD and PSPA testing was also performed on a weekly basis to aid in monitoring the pavement condition.

 

 

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