rolling wheel deflectometer: integrating data in pavement

Rolling Wheel Deflectometer: Integrating Data in Pavement Management

Rolling Wheel Deflectometer: Integrating Data in Pavement Management

Presented by:Thomas Van, PEPresented by:Thomas Van, PE

U.S. Department of TransportationFederal Highway AdministrationU.S. Department of TransportationFederal Highway Administration

Coming Up…Managing Pavements, Why DeflectionDeflection MeasurementsState of the PracticeCase StudySummary

Managing Pavements:Why Deflection?CrackingRuttingRide QualityMaterial Failures

Pavement Failures

Traffic

Managing Pavements:Why Deflection?

As an Indicator for Structure..When will it needs attention?Does Preservation make sense?Did we figure traffic correctly?Were there construction issues?

Measuring Deflection

LaboratoryField

Manual Methods:

Measuring Deflection

Benkelman Beam

Static Device Methods:

Photo of Benkelman Beam, FWD, LaCroix Device

Measuring Deflection

LaCroix Deflectograph

Static Device Methods:

Measuring Deflection

Falling Weight Deflectometer

Static Device Methods:

Measuring Deflection

DynaflectRoad Rater

Steady-State VibratoryMethods:

Measuring DeflectionDynamic Vibratory Device Methods:Texas Rolling Dynamic Deflection (RDD)

Measuring Deflection

Danish Traffic Speed DeflectometerSwedish Road Deflection TesterAmerican Rolling Wheel Deflectometer

High-Speed Device Methods:

The RWD• Measures the continuous

pavement deflection profile due to an 18-kip single axle truck load

• Provides a measure of the overall structural capacity of highway sections

• Information can be used for network-level evaluation and management

• Pre-screener for where to focus project-level efforts (i.e., FWD, coring, etc.)

RWD Benefits• Increased safety. Does

not require lane closures.• Mixes with traffic stream.

No interruption to traveling public.

• Operates over a broad range of speed (5 to 65 mph).

• High data collection productivity.

• Rapid data processing.

RWD Role in DOT OperationsNetwork-Level Project-Level

0

1

2

3

4

5

6

7

8

3+000 4+000 5+000 6+000 7+000 8+000 9+000 10+000Chainage

IRI,

m/k

m

Left WP Right WP

PSI

IRI

RWD

Potential^

FWD

Coring

Lab

10,0

00 la

ne-m

iles

Preservation

Rehabilitation or Reconstruction

100

lane

-mile

s

Indiana SR 1 – 3 Structures

0

20

40

60

80

Mile Marker

Deflection, mils

Good

65 70 75 80 85 90 95

Poor

Good

0

10

20

30

40

50 60 70 80 90 100 110 120 130 140 150

Deflection, mils

Mile Marker

Kansas – US 59

RWD

FWD

* Year of FWD Testing

CHAMPAIGN COUNTYRWD-BASED PMS IMPLEMENTATION

Background• Champaign County’s

network:– 400 lane-miles– Low-volume (farm-to-market)

roads– Asphalt-surfaced. Multiple

resurfacings– Variable surface, ride, and

structural conditions• Current highway budget is

approximately $2M per year

Key InputsRWDVideo imagesSmoothness dataConstruction historyTrafficCost data

County Road 32

0

10

20

30

40

50

60

0 2 4 6 8 10

Thin AC over a surface treatment -

High deflections

US

136

Giff

ord

AC over a cold millings base -

Strongest section

AC over a granular base - Good uniformity

RWDFWD

Mile Marker

Deflection, mils

Structural Conditions

0.6%

41.6%

15.1%15.1%

27.7%

0%

10%

20%

30%

40%

50%

< 10 10 to 20 20 to 35 35 to 50 > 50

Representative RWD deflection, mils

Perc

ent o

f mile

age

Pavement structural conditions vary widely

Excellent

Very Good

Good

Fair

Poor

Complete Treatment Matrix

24

PCI PCI < 35 35 - 50 > 50 High TrafficValue Rating < 45 45 - 75 > 75 Low Traffic

Good Fair Poor Structural Rating

0

4-in AC Mill and Overlay Reconstruction

2-in AC Mill and Overlay

Defer Improvements

4-in AC Mill and Overlay

Chip seal, Microsurfacing

(maximum 2 times)

Representative RWD Deflection, mils

Defer Maintenance

Crack sealing (maximum 1 time)

Excellent

Poor

100

Very Good

Good

Fair

40

65

80

90

30

40

50

60

70

80

90

100

2006 2007 2008 2009 2010 2011

PCI

Unlimited $3M per year $2.5M per year

$2M per year $3M per year (No PM) $2.5M per year (No PM)

$2M per year (No PM) Do Nothing

Network Condition vs. Funding

25

PMS Results• Produced a 5-year maintenance and

rehabilitation plan– Prioritized projects– Recommended treatments

• RWD helped identify the most appropriate treatment for each road– Pavement preservation– Functional improvement– Structural improvement

• 5-year budget analysis showed the consequences of various funding scenarios

SUMMARY

Conclusions

• It’s not just about Ride Quality!!• Cracking and Rutting are

important parameters.• Pavement Structure is too

important to ignore.• Don’t abandon the proven

methods.

Conclusions• RWD is an effective means of measuring

continuous pavement deflections and structurally characterizing pavement sections

• Accuracy and repeatability are suitable for network- and project-level evaluation

• Compares well to other references (i.e., FWD data)

• Can be used in PMS to optimize treatment selection, candidate projects, and funding allocation

Updates • RWD is now available for commercial

testing. ARA is the service provider.• Two pilot programs have been funded in

2008, anticipating more in 2009.• Focusing testing on states that are

interested in incorporating RWD data into their PMS activities

Thank You!

For more information,please contact:Thomas Van, FHWAthomas.van@dot.gov202-366-1341