Airfield Concrete Pavement S th Smoothness

Airfield Concrete Pavement
Smoothness
October 27‐28, 2010
Presented by:
Mr. Tony Gerardi
APR Consultants, Inc.

The Primary Reason We Strive to Build
and Maintain Smooth Pavements is to
Minimize Aircraft Dynamic Response,
and Maximize Aircraft Performance

Roughness Defined
1. Shock Loading
Short wavelength roughness that is too fast for the tires and
suspension system to fully react. (rattles instruments, t jars
avionics)
2. Single Axle Loading
Short wavelength roughness that the tires and suspension system
are capable of reacting to. (Increases O&S costs, passenger
complaints)
3. Whole Aircraft Loading
Longer wavelength roughness that excites the whole aircraft
(Aircraft fatigue damage, reduces braking ability, reduces
pavement life)
Note: Types (1) and (2) can be detected by a 16’ Straightedge or
a Profilograph; Type (3) cannot

Why Be Concerned About Runway
Roughness
Aborted
Takeoff
Poor Braking
Performance
Increased Operational &
Support Costs & Aircraft Fatigue Damage
Reduces Pavement’s Useful Life and
Could Result in Costly Unscheduled Repairs
Pilot and Passenger Complaints

IPRF Research on Airport Pavement Smoothness:
Research Goals ‐ IPRF 02‐4
1. Develop a smoothness handbook for all
stakeholders
2. Overview of capabilities for off the shelf profiler
types to capture data for 16’ straightedge use
3. Develop target smoothness criteria
4. Identify construction practices that result in
smooth pavements

New Pavement Acceptance Specifications
• FAA AC‐150/5370; (P‐501) 16‐Foot Straightedge
using a .25 inch maximum allowable deviation
anywhere along the straightedge.
• California Profilograph; Typical specification is a PI of
5‐7 inches per mile
• Both methods will produce a smooth ride if grade
control is maintained.
• APR’s experience shows both methods to be
conservative

Evolution of Airport Pavement Smoothness 16‐
Foot Straightedge
“Max Deviation Anywhere Along the Length”

Various Profiling Devices
• Walking Profilers
▫ Sufficient Accuracy for Airfield Evaluation
▫ Relatively Inexpensive
▫ Can Track All Event Wavelengths
▫ Some Units Can be Painfully Slow

Various Profiling Devices
• Inertial Profilers
▫ Van, Truck or ATV Mounted
▫ Faster than Walking Type
▫ Sub Millimeter Accuracy
▫ Texture can Adversely
Affect Ride Readings
– Not as Repeatable As
Walking Profilers
– More Expensive
– Difficulty Tracking Longer
Wavelength Events
– Acceleration Room

Other Profilers
Rolling Inclinometer
Wet or Dry Profiler

Device Evaluation Summary
• All Device Types Tested Have the Required Accuracy
to Assess Airport Pavements Using the P‐501
Specification (16‐Foot Straightedge)
• Not All of the Devices can be used to Compare to
Design Grade
• Each Type Has Advantages and Limitations

Evolution of Airport Pavement tSmoothness Assessment
California Profilograph
PI of 5-7 Inches/Mile is Conservative

13
Profilograph
• The California Profilograph
has become the industry standard
for assessing pavement smoothness
Pros:
Faster than a Straightedge
Identifies Multiple Events
Good for Short Wavelength Events
Accepted by the Industry
Matches Diamond Grinding
Process
Cons:
Misses Long Wavelength Events
No Raw Profile is Produced
d
No Baseline Profile for Future
Comparisons

Courtesy: ACPA TB-006P “Constructing Smooth Concrete Pavements”

15
Profile Index
• A Profile Index (PI) of 5 is
Conservative
▫ Great if you can get it, but from
a Ride Quality Perspective, it is
Conservative
• IPRF 02‐4 Compared PI Values to
Aircraft Simulation
▫ Runway with PI’s from 12 to 14
Yielded d Acceptable Ride Quality

16
Taxi: Boeing 737-800 Aircraft 172500 lbs GW
extension 2 (Grade Removed)
Air Temperature = 59 (°F) Field Elevation = 0(f (ft) Headwind = 0( (kts)
Profile Filename = extension2.dat Sim. Start = 0 (ft) RQF = 1.8300
Output Filename = SIM01.out Taxiing Speed = 50 (knots) Complete Simulation = Yes
1.0
0.5
Pilot’s Station Acceleration
0.4
PSA (g's
)
0.0
-0.5
-0.4
CGA (g's)
-1.0
1.0
0.5
0.0
-0.5
-1.0
0.5
Aircraft’s Center of Gravity Acceleration
Runway’s Profile
0.4
-0.4
Elevatio on (in)
0.0
-0.5
0 250 500 750 1000 1250 1500 1750 2000
Distance (feet)
737-800 Conducting a 50-Knot Taxi – Runway had a PI of 12-14

17
The California Profilograph Relative to
a Modern Commercial Aircraft
Boeing 777-200ER
Gear Spacing 84 feet 11 inches
Equates to 3.4 California Profilograph lengths
Or 5.3 Straightedges 16 feet long
Image Courtesy Boeing Commercial Aircraft Company

18
Profilograph Limitations
• Longer Wavelengths are Missed using the Profilograph or 16’ Straightedge
▫ Aircraft Response is Dependant upon Gear Spacing & Speed of Encounter
• This is the Primary Reason APR uses True Profile Measurement
▫ All Wavelengths and Amplitudes are Identified

In-Service Runway
Major Commercial Airport
Elevation (in)
Eleva ation (in)
1
0
-1
-2
2
0
EWR Runway 4L South Extension, 12.5 Feet LOC
EWR Runway 4L South Extension, 12.5 Feet ROC
EWR Runway 4L South Extension, Centerline
12 Feet Left of Center
Centerline
Elevation
(in)
2.5
0.0
12 Feet right of Center
0 500 1000 1500 2000 2500
Distance (feet)

3.0
16-Foot Straightedge Simulation
In-Service Runway
Starting Point = 0 (ft) Threshold Value = 0.25 (in)
Percent Exceeded Threshold (0.25 in) = 6.69% Overall
Dev viation From
Straight Ed dge (in)
2.5
20 2.0
1.5
1.0
0.5
0.25
0.0
0 500 1000 1500 2000 2500
Distance (feet)

3.0
100-Foot Straightedge Simulation
In-Service Runway
Starting Point = 0 (ft) Threshold h Value = 1 (in)
Percent Exceeded Threshold (1 in) = 21.06% Overall
De viation From
Straight Edge (in)
2.5
2.0
1.5
1.0 1
05 0.5
0.0
0 500 1000 1500 2000 2500
Distance (feet)

Aircraft Response to This Runway…
22

23
Corrective Action
• When Analyzed with a California Profilograph
▫ Profile Index may suggest a slightly rough pavement
▫ BUT, the PI trace will miss the 100‐foot long peaks
▫ Grinding off scallops identified by Profilograph will not fix
the problem
• Grind to Desired Grade, Mud Jack or Replace Panels

What do you think of when “Smoothness”
is discussed
• Most stakeholders focus on the 16‐Foot Straightedge
or the Profilograph; The Industry Focus is on the
short wavelengths
• The specifications also require a maximum of .5 inch
deviation to design grade
• Both are important to insure good aircraft ride
quality
• Should incentive pay include adherence to grade
control

Some Airport Owners are Questioning the
Use of PI for Incentive Pay
• Are we paying extra for diamond grinding to obtain
unnecessary smoothness levels
• Should parking aprons, taxiways and runway outer
lanes have the same PI requirement
• Should the decision to diamond grind be on a case
by case basis; especially for non‐keel section
pavements

26
Recommended Option to Assess
Smoothness
• Use True Profile Measurement to Identify ALL
wavelengths
• Opens up the Possibility to Use ANY Straightedge
Length
• True Profile also Serves as the Pavement’s Baseline
Profile for Pavement Management Needs

Why a Baseline Profile
• Enables the owner to track settlement or upheaval
• It’s a new tool in the Pavement Management tool
box
• It is a reflection of the pavement’s structural integrity
(any change in the base, sub‐base or surface is
reflected in the profile measurement)
• It enables the owner to see a problem coming and
plan accordingly

Compare 2006 to 2010
(Grade Removed)
Elevation (in) Elevation (in)
Elevation
(in)
Elevation (in) Elevation (in) Ele evation (in)
0.0
-2.5
0.0
-2.5
0.0
-2.5
0.0
-2.5
0.0
-2.5
00 0.0
-2.5
ATL Runway 10, 15 Feet Left of Center ATL Runway 10, Centerline Profile ATL Runway 10, 15 Feet Right of Center
Runway 10-28 at ATL, 12 Feet LOC Runway 10-28 at ATL, Centerline Runway 10-28 at ATL, 12 Feet ROC
Left of Center
Centerline
2006
Right of Center
Left of Center
Area of Differential Settlement
Centerline
2010
Right of Center
7500 7750 8000 8250 8500 8750
Distance (feet)

Compare 2006 to 2010
(Grade Removed)
1
0
ATL Runway 10, Centerline Profile
Runway 10-28 at ATL, Centerline
Elevation (in)
-1
-2
-3
2006
-4
1
0
Ele evation (in)
-1
-2
-3
800 cu.yds.
3”
2010
-4
8000 8100 8200 8300 8400 8500 8600 8700 8800
Distance (feet)

500-Foot Straightedge Simulation
ATL 10 CL_2006.dat
Starting Point = 0 (ft) Threshold Value = 1 (in)
Percent Exceeded Threshold (1 in) = 26.46% Overall
4.0
Vertical Curves
2006 Baseline Data
Deviation From Straigh ht Edge (in)
3.5
3.0
25 2.5
2.0
1.5
1.0
0.5
1
0 1000 2000 3000 4000 5000 6000 7000 8000
0 000 000 3000 000 5000 6000 000 8000
Distance (feet)

4.0
500-Foot Straightedge Simulation
ATL 10 CL.dat
Starting Point = 0 (ft) Threshold Value = 1 (in)
Percent Exceeded Threshold (1 in) = 32.12% Overall
Vertical Curves
2007 Data
Deviation From Straigh ht Edge (in)
35 3.5
3.0
25 2.5
2.0
15 1.5
1.0
0.5
Area of Settlement
1
0.0
0 1000 2000 3000 4000 5000 6000 7000 8000
0 000 000 3000 000 5000 6000 000 8000
Distance (feet)

4.0
500-Foot Straightedge Simulation
ATL RW 10_CL.dat
Starting Point = 0 (ft) Threshold Value = 1 (in)
Percent Exceeded Threshold (1 in) = 45.55% Overall
Vertical Curves
2010 Data
Deviation From Straigh ht Edge (in)
35 3.5
3.0
2.5
2.0
1.5
1.0
0.5
Area of Settlement
1
0 1000 2000 3000 4000 5000 6000 7000 8000
0 000 000 3000 000 5000 6000 000 8000
Distance (feet)

What is the Cause of the Differential
Settlement
• Something is different in this area.
• Is this a wet area
• Different type of fill material
• Different compaction
• What about the Parallel Taxiway in the same area
• The rate of settlement seems to have accelerated since 2007.
• What will it be next year
• Does not affect aircraft response at this point.
• How much is too much

IPRF Research on Airport Pavement
Smoothness: Research Goals ‐ IPRF 02‐4
1. Develop a smoothness handbook for all
stakeholders
2. Overview of capabilities for off the shelf profiler
types
3. Identify construction practices that result in
smooth pavements
4. Develop target smoothness criteria

String Line Sag
Saw cuts and
string line stakes
Wand pressure, cable tension,
curling and warping

60 6.0
5.5
5.0
4.5
Elevation (in n)
4.0
35 3.5
3.0
2.5
Potential Birdbath Area
Paving Lane Seam
2.0
1.5
10 1.0
0.5
0.0
0 10 20 30 40 50 60 70
Distance (feet)
Birdbath Detection – Transverse Profile

Birdbath
Birdbath Detection – Flood Area

Recommended Target Smoothness Values
for All Airfield Pavements
• Rolling Straightedge Length
• Threshold of Acceptability
• Pavement Section Length
500 Feet
• Allowable SSI per Section 5%
• Must Repair Value for Keel Section
.5‐Inch
• Must Repair Value for Outer Lanes
.75‐Inch
25 Feet
.35 Inches
Target Values Require Field Testing
Note 1: Repeated bumps (3 or more) in the keel section .25 inches or greater will require repair.
Note 2: Any longitudinal step bump greater than .25‐inch in the keel section will require repair.
Note 3: Exceptions apply for intersecting runways, drains on taxiways and ramps.

(in)
10 1.0
0.9
0.8
16-Foot Straightedge g Emulation
Straightedge g Smoothness Index (16-Foot)
% Exceeded .25” Threshold Per Section
Runway 24R; Station 0+00 is at Painted Threshold
Starting Point = 0 (ft) Threshold Value = 0.25 (in)
Percent Exceeded Threshold (0.25 in) = 0.88% Overall
0.0 0.0 4.5 0.0 0.0
0.0 0.0 4.5 0.0 0.0
SSI is a method that quantifies the effect of multiple bumps & dips
.88% Overall
Deviatio on From Str raight Edge
0.7
0.6
05 0.5
0.4
0.3
0.2
0.1
Threshold of acceptability
Must Repair
Threshold of Acceptability
025 0.25
00 0.0
0 50 100 150 200 250 300 350 400 450 500
Distance (feet)

Another Possible Smoothness Assessment
Method for Airfield Pavements
(Not Part of IPRF Study)
• Use Profilograph
• Threshold of Acceptability
• Pavement Section Length 500 Feet
• Must Repair Value for Keel Section .5‐Inch
• Must Repair Value for Outer Lanes .75‐Inch
25 Feet
10‐12 12 Inches (Keel Section)
Target Values Require Field Testing
• Include True Profile for Grade Control and to Establish a
Baseline Profile
• Baseline Profile Data is a Deliverable

Things to Consider
1. Tie incentive pay to grade control (long wavelength
roughness) in addition to P‐501 or
PI values; example‐commuter jet video
2. Field test “Target” smoothness criteria
3. Validate APR’s experience that t current specs are
conservative; need additional field tests comparing
aircraft ride quality to PI
4. Consider a different smoothness criteria for outer
lanes, taxiways and aprons
5. Should diamond grinding decisions be made on a
case by case basis

IPRF Handbook
• Handbook Can Be Obtained through the IPRF Office
▫ 02‐04 “Airfield Concrete Pavement Smoothness ‐ A Reference”
▫ http://www.iprf.org/products/main.html
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