Continuous Deflection for Comprehensive Pavement Assessments

Thursday, May 30, 20191:00-3:00 PM ET

TRANSPORTATION RESEARCH BOARD

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Credit earned on completion of this program will be reported to RCEP. A

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Purpose

To discuss the applications of continuous pavement deflection.

Learning Objectives

At the end of this webinar, you will be able to:

• Describe the limitations of traditional assessments

• Identify continuous deflection capabilities• Describe how other agencies are applying

results• List the benefits and advantages of

comprehensive assessment

Comprehensive Pavement Assessments Using Continuous DeflectionTRANSPORTATION RESEARCH BOARD WEBINAR1:00 PM – 2:30 PMTHURSDAY, MAY 30, 2019

Agenda

1. Introduction 2. Pavement assessment3. Continuous deflection technology4. Applications to date5. Benefits to agencies6. Questions & answers

May 30, 2019 Comprehensive Pavement Assessments using Continuous Deflection 2

1. Introduction

Dr. Nadarajah Sivaneswaran (Siva), P.E.Federal Highway Administration

2. Pavement Assessment

Dr. Gerardo Flintsch, P.E.Center for Sustainable Transportation Infrastructure,

Virginia Tech

Introduction

Pavement Management – A key Asset Management business process

• Pavements are the most “valuable” asset in terms of patrimonial value

• Impact safety, user costs, noise generation, …Structural condition evaluation and monitoring:

– A fundamental block of an efficient pavement management program

Why do we “manage” our pavements?

To preserve our infrastructure value– Key component of the asset management

To develop “optimum” pavement preservation and renewal programs– Better Use of Available Resources

To provide a level of service that the user considers appropriate– Maintain a State of

Good Repair

State of the Practice on Pavement Condition Data

Surface condition– Easy to obtain– Collected for the road network– Used to assess the overall condition– Implemented in a PMS

Structural capacity/condition– Hard to obtain– Seldom collected for the network– Used to design pavement treatment

7

Flintsch, G.W., and McGhee, K.K., NCHRP Synthesis 401 - Quality Management of Pavement Condition Data Collection, Transport Research Board, NAS-NRC,2009, Washington, DC, 155 pp. http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_syn_401.pdf.

Pavement Condition “Quality” Measures & Performance Indicators

Service and User Perception

Physical Condition

Structural Integrity / Load-Carrying Capacity

Safety andSufficiency

Environmental Impact

Serviceability (PSI, IRI)

Distress(PCI)

Deflection(FWD)

Friction (FN)/ Macrotexture

Tire/PavementNoise

Is cracking a good indicator of structural integrity?

150 160 170 180 190 200 210 220 2300

0.5

1

1.5

2

Pavement Condition on I81 South

Milepost

SCI 30

0 (mil)

150 160 170 180 190 200 210 220 2300

20

40

60

80

100

Fatig

ue C

rack

ing

Seve

rity

1 (f

t 2 )

Structural Condition TSDFunctional Condition PMS

SCI300vs Cracking

Destructive– Coring, trenches, material testing, etc.– Time-consuming, expensive, and

degrade pavement Non Destructive Evaluations (NDE)

– Deflection Measuring Equipment– Ground Penetrating Radar– Infrared Thermography– …

“Traditional” Structural Capacity Assessment

Deflection Measurement Technologies “Static” Measurement

Devices

Moving Devices with Stationary Measurement Equipment

Moving Measurement Vehicles with Non-Stationary Measurement Apparatus

3. Continuous Deflection Technology

Dr. Gerardo Flintsch, P.E.Center for Sustainable Transportation Infrastructure,

Virginia Tech

Continuous Deflection in the US

13Advancing Transportation Through Innovation

Development

Assessment

Evaluation

Demonstration

Implementation

Several State Efforts

Idaho

Virginia

Louisiana

Nationwide

SHRP 2 R06 (F) Assessment of Continuous Pavement Deflection Measuring Technologies

0

2

4

6

8

10

12

14

105 110 115 120 125 130 135 140

RWD

Defle

ctio

n (m

ils)

Mile Marker

RWD Deflection (0.1 mile avegrage) Moving Average

Sectioning (based on last resurfacing)

RWD

0.000

0.100

0.200

0.300

0.400

0.500

0.600

0.700

0.800

0.900

1.000

0 500 1000 1500 2000 2500 3000 3500 4000

Defle

ctio

n Sl

ope

[mm

/m]

Chainage [m]

10m averages

100m averages

TSD

http://onlinepubs.trb.org/onlinepubs/shrp2/SHRP2prepubR06F.pdf

Network Level Pavement Structural Evaluation

Assess and evaluate capability of traffic speed deflection-related devices for pavement structural evaluation at network level

Develop methodologies for enabling use of devices in pavement management

https://www.fhwa.dot.gov/publications/research/infrastructure/pavements/15074/15074.pdf.

Demonstration of Network Level Pavement Structural Evaluation with Traffic Speed Deflectometer

Objective: To assess the feasibility of and demonstrate the use of the TSD for network level structural evaluation for use in the participating agencies’ pavement management application and decision making

Partners: FHWA, CA , GA , ID , IL , NV , NY , PA , SC , VATransportation Pooled Fund Study TPF-5(282)

ESC Inc. Greenwood Engineering VTTI TRL

http://www.pooledfund.org/Details/Study/518

Traffic Speed Deflectometer

SCI300

Data Collection & Processing

Pavement deflection velocityLaser Doppler

Pavement deflectionIntegration of deflection slopes

Temperature corr. deflectionsStrain-based procedure

Deflection IndicesSCI300, DSI, SNeff,

Pavement deflection slopeVv / Vh

Structural Indices

SCI12 (SCI300):– D0 – D12

DSI4-12:– D4 – D12

SNeff:– SIP = D0 – D1.5Hp

– SNeff = k1 * SIPk2 * (Hp)k3

TPF-5(282) Main Products

Approaches for classifying the structural condition• Mechanistic approach based on tensile strain at the asphalt

bottom• Percentile from the cumulative distribution of SCI300• SNeff derived from TSD data

Framework to incorporate the TSD-measured structural condition within a SHA’s PMS • Structural condition can be use to enhance treatment selection

20

RAPTOR

May 30, 2019 Continuous Deflection for Comprehensive Pavement Assessments 21

Network Level Pavement Structural Testing with the Traffic Speed Deflectometer (TSD) in VirginiaPilot Implementation Collected continuous deflections for the Interstate and

primary roads

Enhanced project selection decision tree

Pavement Surface

Distresses

Fatigue Cracking

Transverse Cracking

Rutting

Patching

…….

Condition Index

Decision Process

(Matrices)

Treatment Selection

Augmented Decision Process

Structural Condition

Final Treatment Selection

Do Nothing

Preventive Maintenance

Corrective Maintenance

Rehabilitation

Reconstruction

Fair Structural Condition

4. Applications to Date

Dr. Brian Diefenderfer, P.E.Virginia Transportation Research Council

Use of Network Structural Testing

Scoping network level needs:

– Overall health of the pavement

– Structural index to use in PMS

– Remaining structural life– Resource allocations

Screening sections:– Strong vs. weak sections– Heavy treatment vs.

preservation treatment– Need more detailed

evaluation

24

VDOT Enhanced PMS Decision Trees

VTRC Report 13-R9

Correlation Between Structural and Functional Condition

DistressSpearman Rank

Coefficient

Center Deflection

LDR -0.1444NDR -0.1285CCI -0.1254IRI 0.0597

Rut Depth 0.0319Total Alligator

Cracking0.1382

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

0 20 40 60 80 100

FWD

Cent

er D

efle

ctio

n (m

ils)

Load Related Distresses (LDR)

I-81 South; Functional Vs. Structural Parameters

VTRC Report 13-R9

Impact of Structural Capacity

0 2 4 6 8 1040

50

60

70

80

90

100

Expected Life (Years)

CC

I

Pavement in Bad Structural ConditionPavement in Good Structural Condition

The pavement that isin bad structuralcondition deterioratesfaster

−−=tcbaetCCI

1ln*100)(

Poor structural condition deteriorates faster

Structural Health Index VTRC Report 13-R9, Structural index using FWD data collected at the network-level Modified SCI (MSI)→ The SCI concept was introduced by the Texas DOT for network-level analysis

→ MSI was proposed in 2012 as a modified version of the SCI

→ Simplification of the 1993 AASHTO Overlay Design Method→ Based on deflection, traffic level, and calculated Mr

𝑆𝑆𝑆𝑆𝑆𝑆 =𝑆𝑆𝑁𝑁𝑒𝑒𝑒𝑒𝑒𝑒𝑆𝑆𝑁𝑁𝑟𝑟𝑒𝑒𝑟𝑟

𝑀𝑀𝑆𝑆𝑆𝑆 =0.4728 ∗ 𝐷𝐷0 − 𝐷𝐷1.5𝐻𝐻𝐻𝐻

−0.4810 ∗ 𝐻𝐻𝑝𝑝0.7581

0.05716 ∗ (log(𝐸𝐸𝑆𝑆𝐸𝐸𝐸𝐸) − 2.32 ∗ log Mr + 9.07605 2.36777)

Performance and Cost Differences

0

2

4

6

8

10

12

0 0.25 0.5 0.75 1 1.25 1.5

Expe

cted

Ser

vice

Life

(Yea

rs)

MSI

Expected Life of CM Treatment

$0.00

$0.20

$0.40

$0.60

$0.80

$1.00

$1.20

$1.40

$1.60

0 0.25 0.5 0.75 1 1.25 1.5

Expe

cted

Cos

t per

Mile

(Mill

ions

)MSI

Expected Cost of CM Treatments - 25 Year Service

Expected Cost

Rounded Costs

5x increase in cost

Transitional Research

FWD to traffic speed deflection devices (TSDDs)

FHWA study, 2011 & SHRP2 study, 2013– Identified several TSDDs

FHWA study, 2012-2015 & TPF-5(282), 2013-2017– Compared vehicle-measured pavement deflection with embedded

sensors– Compared qualitative ranking of structural condition with FWD– Identified analysis parameters

TPF-5(282) Data Example

TSDD

Implementation Examples

Idaho – Corridor management

• Network structural info with ME performance predictions• Estimate future maintenance schedules

– Planned versus reactive maintenance

Virginia– Previous augmented PMS decision trees

• Replacing FWD with TSDD info

TPF-5(282) Findings

Short- and long-term repeatability is good– More work needed for temperature correction

TSD and FWD followed similar trends– But not a one-to-one replacement as expected

Little relationship between TSD results and PMS surface condition– Shows need for structural testing

2017 Testing in Virginia

4,000+ miles of testing on interstate and primary routes

Study impact on PMS results by including TSDD-based structural response

Deflection indices, rutting, ride quality, cracking, pavement and roadway images, cross slope

VDOT 2017, Remaining Work

Identify structurally strong and weak sections – Compare to PMS decision making and rehab history– Compare to previous structural data (where available)

Determine ranges of calculated indices that identify strong versus weak structural condition– Structural sufficiency vs design – Similar budget output from PMS– Combination?

deflection

thickness

cracking

rutting and IRI

Why a sudden onset of cracking?

Pooled Fund Study, 2018-2021

TPF 5(385), Pavement Structural Evaluation with Traffic Speed Deflection Devices

Agency partners– Arkansas, FHWA, Georgia, Idaho, Illinois, Indiana, Kansas, Louisiana,

Michigan, Minnesota, Mississippi, North Carolina, New Mexico, Oklahoma, Pennsylvania, South Carolina, Tennessee, Texas, Virginia, Vermont, West Virginia

Pooled Fund Study Objectives/Scope

Provide means to conduct demonstration testing– ARRB Group TSD & Dynatest RAPTOR

Develop specifications for data collection and guidelines for PMS application

Demonstrate– How to use data to support project level decision-making– Costs (and any savings) through case studies

Conduct workshops and prepare training

Pooled Fund Study Commitment LevelsOption 1

– Participation in the study for one agency rep (no testing) = $15,000 / year

Option 2a– Option 1 plus one day of testing on agency designated routes (~100-200

miles) = $45,000 / year

Option 2b– Option 2a plus additional days of testing = $32,000 / day / year

Pooled Fund Study Status

Project stated October 2018

Working with agencies to conduct testing– Agency designated routes

2019 testing completed for 6 of 21 agencies– Remainder are in planning phases

Open to adding additional agency partners

5. Benefits to Agencies

Dr. Brian Diefenderfer, P.E.Virginia Transportation Research Council

Benefits

Pavement rehabilitation decision making– More complete information to

make better decisions– Multi-billion dollar implications

Benefits to Agencies

Allow realistic production for network-level structural testing– Significant portions of a network can be covered daily– Include structural properties in PMS decision-making

All this with…– Increased operator and public safety– Continuous (nearly) rather than discrete measurements

Segment 1Segment 2

Virginia Example #1

Segment 3

Virginia Example #2

VDOT division investigating corridor widening project– About 85 directional miles

Initial assumption was to reconstruct entire alignment– Combined use of FWD and TSDD data – Showed that about 65% was structurally adequate

Cost avoidance in the hundreds of millions of dollars

6. Questions and Answers

Dr. Nadarajah Sivaneswaran (Siva), P.E.Federal Highway Administration

Today’s Speakers• Nadarajah Sivaneswaran, Federal

Highway Administration, nadarajah.sivaneswaran@dot.gov

• Brian Diefenderfer, Virginia Department of Transportation, brian.diefenderfer@vdot.virginia.gov

• Gerardo Flintsch, Virginia Tech, flintsch@vt.edu

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