LTPP Lessons Learned: National Experiment

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LTPP Lessons Learned National Experiment

• Tuesday December 16, 2014
• Bismarck, ND
• Jack Springer, P.E. - FHWA
• Gabe Cimini, PM LTPP - NCRSC

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Lessons Learned Overview

• Program Benefits and Return on Investment
• Construction Effects on PCC Pavement Performance
• Specific SPS-2 Lessons Learned
• Pavement Performance
• Pavement Design
• Materials Testing
• Data Collection
• Future Benefits

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LTPP Benefits

• The LTPP program has generated a wide range of
  benefits all across the pavement engineering and
  performance spectrum.

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Return on Investment
LTPP by the Numbers
LTPP Resource Statistics
Requests for Data 48,000 Requests
Registered LTPP Website Users 3,000 Users (in 75 Countries)
Published Documents Resulting from LTPP Data 500 Publications
ASCE Paper Contest 60 Entries
Distress Manuals 20 State Agencies
FWD Calibration Centers 500 Calibrations
WIM Systems 550 Installations
SPS Traffic Pooled Fund Study Installations 21 WIM Sites Installed
MRL Materials 2,000,000 Pounds Available
MRL Shipments 17,000 Pounds Delivered
The numerous innovations that have directly
resulted from the LTPP program include
procedures, tools, manuals, and research findings
that have been implemented across the United
States and abroad.
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Return on Investment
Cost Savings
LTPP has already realized over 2 Billion in
savings, with the potential for even greater
future savings.
Savings To Date Projected Cumulative Future Savings (2015-2024) Projected Cumulative Future Savings (2015-2024)
Savings To Date No Additional Monitoring Continued Monitoring
2.1 Billion 2.28 Billion 4.56 Billion
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SPS-2 Lessons LearnedPavement Performance

• Standardizing AVC and WIM data storage formats
  (Card 4 and Card 7, respectively)
• The initial IRI of SPS-2 sections after placement
  ranged from 0.76 to 2.19 m/km with a mean of 1.30
  m/km
• Increased roughness, faulting and transverse
  cracking are more prevalent in wet climates
• Pavements located in areas of higher annual
  freeze-thaw cycles experience more spalling

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SPS-2 Lessons LearnedPavement Design

• Widened slab sections show less faulting than
  conventional width slabs
• Sections with aggregate base show the highest
  joint faulting level. Sections with LCB and PATB
  have the lowest joint faulting
• Thinner (203 mm) slabs show more transverse
  cracks than thicker slabs. Sections with a
  thinner slab and a widened slab show the highest
  level of transverse cracking

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SPS-2 Lessons LearnedPavement Design (cont.)

• JPCP constructed on PATB were smoother than
  sections constructed on LCB or untreated
  aggregate base
• Sections with PATB show the lowest total
  longitudinal cracking levels, while the sections
  with LCB show the highest longitudinal cracking
• Sections with PATB show the lowest percentage of
  slabs cracked transversely, while the sections
  with an LCB show the highest transverse cracking

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SPS-2 Lessons LearnedPavement Design (cont.)

• In general, LCB provided the worst performance
  and PATB over DGAB provided the best performance
• Longitudinal cracking was influenced by base type
  and slab thickness
• Widened lanes contributed to lower transverse
  joint faulting

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SPS-2 Lessons LearnedPavement Design (cont.)

• Thicker slabs were found to have more initial
  roughness as compared to thinner slabs
• The presence of drainage was the driving factor
  of change in roughness with time. Sections with
  drainage showed a slower increase in roughness
  than those without drainage
• 900 PSI sections typically show map cracking and
  550 PSI sections typically show polished
  aggregate
• 14 lane 1 of thickness

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SPS-2 Lessons LearnedPavement Design (cont.)
Rigid Pavement Design
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SPS-2 Lessons LearnedMaterials Testing

• JPCP constructed on coarse-grained soil were
  smoother (lower initial IRI) than those
  constructed on fine-grained soils
• PCC slabs placed on LCB displayed the largest
  amounts of curling and slabs placed on ATB
  displayed the smallest amounts of curling
• Concrete performed the worst with a lean concrete
  base (LCB) and the best with an asphalt treated
  base (ATB)

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SPS-2 Lessons LearnedMaterials Testing (cont.)

• Six inches of LCB has approximately the same
  stiffness as 8 inches of ATB, both of which are
  less stiff than 8 inches of dense graded
  aggregate base (DGAB)
• Creating the Materials Reference Librarywhich
  allows researchers to obtain and test materials
  used in constructing specific LTPP sections

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SPS-2 Lessons LearnedMaterials Testing (cont.)

• Collecting periodic non-destructive testing
  measurements to allow the backcalculation of
  in-situ moduli
• Developing standardized laboratory and field
  testing protocols
• Providing materials data for calibrating M-E PDG
  damage functions and performing M-E PDG pavement
  designs

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SPS-2 Lessons LearnedData Collection

• The IRI trend over time depends heavily on the
  initial IRI, the traffic loadings, and the extent
  of joint faulting
• Loads below design table (2 million)
• Standardizing data collection and quality control
  practices
• Pavement distress
• Automated profile
• FWD

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SPS-2 Lessons LearnedData Collection

• Indiana Department of Transportation found that
  an FWD that was only 1 mil out of calibration
  resulted in additional construction and
  maintenance costs of 17,000 per mile

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Future Benefits

• Looking forward, there are many potential
  benefits LTPP can provide. A partial listing
  includes
• Increasing service lives for new and
  rehabilitated pavements,
• Comparison of new vs. existing material
  performance

We see the LTPP database serving into the
indefinite future as a key component of the
agencys pavement research activities, and those
activities will benefit substantially from the
many LTPP data collection and analysis activities
in FY 2010 -FY 2015 that are mentioned in the
FHWA document. Victor Mendez, Chairman Twenty-thi
rd letter report of the Transportation Research
Board Long-Term Pavement Performance Committee
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Future Benefits (continued)

• Effects of specific design features
• SHRP 2 support
• Determining the impact of environment on
  performance
• Baseline data sets for agencies to evaluate
  performance
• Year-to-year checks against agency pavement
  management system/pavement condition index data

LTPP is a major contributor toward assuring
that we will have good pavements into the 21st
Century. Charlie Churilla, An Investment in
the Future Roads Bridges, August 2001
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Future Benefits (continued)

• MEPDG local calibration and model refinement
• Top-down vs. bottom-up cracking
• Improved rutting prediction
• Improved curing procedures to reduce built-in
  temperature gradients
• Next design procedure (and state-specific design
  procedures)
• Optimizing treatment selection
• Constructing new sections to expand inference
  set
• Calibration of new field data equipment
• Refining concrete coefficient of thermal
  expansion (CTE) test protocol
• Understanding/properly addressing curl and warp

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Curl and Warp Study040215
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Curl and Warp Study040213
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For more information http//www.fhwa.dot.gov/res
earch/tfhrc/programs/infrastructure/pavements/ltpp
/
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ave.com/
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