Jeffrey L. RapolJeffrey L. Rapol, Civil EngineerFederal Aviation Administration

Airport Engineering Division, AAS-100800 Independence Ave, SW Room 621V

Washington, DC 20591Phone: (202) 267-7474; Fax: (202) 267-3688

jeffrey.rapol@faa.gov

Qiang WangQiang Wang, Ph.D.SRA International Inc.

1201 New Road, Suite #242Linwood, NJ 08221, U.S.A.

Phone: (609) 601-6800; FAX (609) 601-6801qiang_wang@sra.com

Outline of PresentationOutline of Presentation

Introduction to Runway GroovesIntroduction to Runway Grooves

Groove Measurement and Identification SystemGroove Measurement and Identification System

Groove Identification Program – Groove Identification Program – ProGrooveProGroove

--- Procedures--- Procedures

--- Techniques--- Techniques

--- Functions--- Functions

Verification of Verification of ProGrooveProGroove ProgramProgram

When aircraft tires or highway vehicle tires roll over water covered or

flooded pavements, water may penetrate between the tire and the

pavement. This penetration results in the formation of water pressure which

raises a portion of the tire off the pavement.

Introduction to Runway GroovesIntroduction to Runway Grooves

This pressure increases as the speed of the vehicle

increases, supporting more and more of the tire,

until, at a critical speed termed the hydroplaning

speed, the tire is supported only by the water and

loses all contact with the pavement.

Tire Hydroplaning

Cutting or forming grooves in existing or new pavement, which would allow rain water to escape from beneath tires of landing aircraft, is a proven and effective technique for providing skid-resistance and prevention of hydroplaning during wet weather.

The FAA standard groove configuration is 1/4 inch (6 mm) in depth by 1/4 inch

(6 mm) in width by 1 1/2 inch (38 mm) center to center spacing.--- FAA: AC 150/5320-12C

''4

1 ''

4

11

''4

1 ''

2

11

Introduction to Runway GroovesIntroduction to Runway Grooves

The airport operator should periodically measure the depth and width of a runway's grooves to check for wear and damage.

--- FAA: AC 150/5320-12C Groove Tolerance.

Depth and Width: At least 90% grooves ≥ 3/16 inch;

At least 60% grooves ≥ 1/4 inch;Not more than 10% grooves ≥ 5/16 inch.

Center-To -Center Spacing:

1-3/8 inches ≤ Spacing ≤ 1-1/2 inches.

--- FAA: AC 150/5370-10E

Introduction to Runway GroovesIntroduction to Runway Grooves

''

4

1

''4

1

''

2

11

Using a laser displacement sensor, the rapid measurement of surface elevation profiles can be achieved to sufficient accuracy and at fine enough sample spacing to define the characteristics of transverse grooves on airport runways.

Groove Measurement andGroove Measurement and Identification SystemIdentification System

Groove IdentificationProGroove

Signal Acquisition Unit

Acceleration Sensor

Displacement Sensor

Distance Sensor

Grooves on Airport Runway

The computer program, ProGroove, was developed which automatically identifies grooves in an elevation profile and computes the dimensions of the grooves.

Groove Identification ProgramGroove Identification Program

The profile data is first high-pass filtered at 0.07 cycle/ft to remove the roughness components in the profile.

The high-pass filtered profile data is followed by low-pass filtering at 3.3 cycle/ft to provide a datum against which groove-like disturbances can be compared.

The low-pass filtered datum provides a moving average of the profile which lies between the top and the bottom of the grooves for comparison.

Groove-like disturbances of joints in concrete pavements are found and removed from the counted grooves.

The potential groove depth and width are double checked for assuring the groove depth and width within the defined limits.

The results of the groove depth and width are statistically analyzed, displayed, and printed out to the files.

Groove Identification ProcedureGroove Identification Procedure

1.

2.

3.

4.

5.

6.

To find the start point and end point of each groove is performed on checking

the difference between the sample value and the low-pass criteria.

-4.00E-01

-3.00E-01

-2.00E-01

-1.00E-01

0.00E+00

1.00E-01

2.00E-01

9.2 9.21 9.22 9.23 9.24 9.25

Selcom

SelAve

Comparing with Moving Average of the ProfileComparing with Moving Average of the Profile

Find Start Point and End Point of each GrooveFind Start Point and End Point of each Groove

Yes

Yes

Yes

No

Give TD = threshold of depth, TW= threshold of width TS = threshold of, space, TJ = threshold of joint Set initial number of grooves, I = 1 Set initial number of points in the groove, J = 0 For each sample point, K No. Go to Subroutine of Calculation K ≤ K max of groove depth Calculate the minimum number of points in each groove, N(v) D = Sample data - Low pass filter data No D > TD Yes No No J < N(v) J < N(v) Yes J = 0 J = 0 Set the start point of the groove, Nlow(I) = K Count the number of points in the groove, J = J + 1 Set the end point of the groove, Nup(I) = K Increase the number of grooves, I = I +1

1. The start point is localized at the difference between the sample data and filter data is greater than the given depth threshold.

2. Calculate the minimum number of points in each groove, N(v), which depends on the vehicle speed.

3. If the number of satisfied difference between the sample and filter data is greater than the N(v), the potential groove is identified.

4. Then, the end point is found as the difference between the sample data and filter data less than the depth threshold.

Critical Frequency Depends on the Vehicle SpeedCritical Frequency Depends on the Vehicle Speed

The vehicle speed usually changes at the start and end periods of test. If using low-pass filter to identify the grooves , the critical frequency can be adjusted to the vehicle speed on the specific time interval.

-0.35

-0.3

-0.25

-0.2

-0.15

-0.1

-0.05

0

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Time, s

Se

lco

m V

alu

e, i

n.

Selcom

Low Pass: 1 HzLow Pass: 10 Hz

Low Pass: 50 Hz

The profile data is first high-pass filtered at 0.07 cycle/ft to remove the roughness components in the profile.

The high-pass filtered profile data is followed by low-pass filtering at 3.3 cycle/ft to provide a datum against which groove-like disturbances can be compared.

The low-pass filtered datum provides a moving average of the profile which lies between the top and the bottom of the grooves for comparison.

Groove-like disturbances of joints in concrete pavements are found and removed from the counted grooves.

The potential groove depth and width are double checked for assuring the groove depth and width within the defined limits.

The results of the groove depth and width are statistically analyzed, displayed, and printed out to the files.

Groove Identification ProcedureGroove Identification Procedure

1.

2.

3.

4.

5.

6.

Remove the Joints from the Test DataRemove the Joints from the Test Data

To determine the joints from a series of grooves is based on the two normally

spaced grooves. It is obvious that the joint space is much greater than the normal

groove space. Distance Between Two Grooves

0 2 4 6 8 10 12 14 16 18

0.47

3.99

5.35

6.66

8.16

9.67

11.34

13.13

14.55

16.00

17.35

18.72

20.31

21.83

23.52

Tim

e,

s.

Groove Distance, in.

The profile data is first high-pass filtered at 0.07 cycle/ft to remove the roughness components in the profile.

The high-pass filtered profile data is followed by low-pass filtering at 3.3 cycle/ft to provide a datum against which groove-like disturbances can be compared.

The low-pass filtered datum provides a moving average of the profile which lies between the top and the bottom of the grooves for comparison.

Groove-like disturbances of joints in concrete pavements are found and removed from the counted grooves.

The potential groove depth and width are double checked for assuring the groove depth and width within the defined limits.

The results of the groove depth and width are statistically analyzed, displayed, and printed out to the files.

Groove Identification ProcedureGroove Identification Procedure

1.

2.

3.

4.

5.

6.

Remove the Joints from the Test DataRemove the Joints from the Test Data

The potential groove depth and width are double checked for assuring thegroove depth and width within a reasonable range.

-1.4

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

23.3 23.32 23.34 23.36 23.38 23.4 23.42 23.44 23.46 23.48 23.5

Time, s

Se

lco

m, i

n.

Checked by Depth

Checked by Width

The profile data is first high-pass filtered at 0.07 cycle/ft to remove the roughness components in the profile.

The high-pass filtered profile data is followed by low-pass filtering at 3.3 cycle/ft to provide a datum against which groove-like disturbances can be compared.

The low-pass filtered datum provides a moving average of the profile which lies between the top and the bottom of the grooves for comparison.

Groove-like disturbances of joints in concrete pavements are found and removed from the counted grooves.

The potential groove depth and width are double checked for assuring the groove depth and width within the defined limits.

The results of the groove depth and width are statistically analyzed, displayed, and printed out to the files.

Groove Identification ProcedureGroove Identification Procedure

1.

2.

3.

4.

5.

6.

Depth, Width and Standard Deviations of the GroovesDepth, Width and Standard Deviations of the Grooves

Storage Information of Groove Identification to a FileStorage Information of Groove Identification to a File

Verification to Manual MeasurementsVerification to Manual Measurements

The groove data were tested at the Atlantic City Airport on October 22, 2008. Instrumental test and manual measurement were recorded for ProGroove analysis.

Verification to Manual MeasurementsVerification to Manual Measurements

ProGroove and Manual Measurement at ACY in Slab 14

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

1 21 41 61 81 101 121 141 161 181

Groove Number

Gro

ove

Dep

th, i

n

Manual

ProGroove

Standard Deviation = 0.02044

Verification to Manual MeasurementsVerification to Manual Measurements

ProGroove and Manual Measurement at ACY in Slab 14

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

1 21 41 61 81 101 121 141 161 181

Groove Number

Gro

ove

Dep

th, i

n

Manual

ProGroove

Standard Deviation = 0.02044

1

2

3

t1 = 14.40988 st2 = 14.41913 st3 = 14.42788 s

Select three typical points for comparisonSelect three typical points for comparison

Verification to Manual MeasurementsVerification to Manual Measurements

ProGroove – Manual = Error

1 0.270 – 0.166 = 0.104 large

2 0.216 – 0.203 = 0.013 small

3 0.192 – 0.188 = 0.004 very small

Error Reason: Manual measurement can not reach the tip of narrow groove.

0.270

0.166

t 1 = 14. 4099

12 3

0.203

0.216

0.1920.188

t 2 = 14. 4191

t 3 = 14. 4279

ConclusionsConclusions

ProGroove software can automatically identify the airport runway

grooves by signal processing of the instrumental test data.

ProGroove software provides the groove number, location, depth and

width, as well as a series of statistical results for groove quality analysis.

The comparison of analyzed data from ProGroove software with manual

measurement shows good coincidence.

The results of groove analysis can be used for verifying the initial

construction of the groove quality or supplying the recommendations to

the airport’s maintenance program.

AcknowledgmentsAcknowledgments

• NAPTF, FAA

– Satish Agrawal

– Jeffrey Gagnon

– Gordon Hayhoe

– David R. Brill

– Robert Flynn

– Navneet Garg

– Albert Larkin

– Frank Pecht

• SRA

– Chuck Teubert

– Jerry Connelly

– Edward Guo

– Hector Daiutolo

– Izydor Kawa

– Injun Song

– Harkanwal Brar

– James Zargan