The goal of the literature review was to identify
available reports on the response and performance of rehabilitated flexible and
rigid pavements and to summarize findings relevant to the objectives of the
current study.
The Federal Highway Administration (FHWA) and the
National Cooperative Highway Research Program (NCHRP) have sponsored numerous
studies to assess LTPP SPS experiment statuses, construction adequacies, and
key data element availability (e.g., traffic, subgrade, materials, monitoring,
etc.) and to conduct preliminary analyses of the collected data. This chapter contains
a summary of findings from previous investigations related to the effect of key
design and construction features and site conditions on performance of flexible
and rigid rehabilitated pavements. The literature review findings are presented
in table 1 through table 6.
Publication |
Major Findings |
Current Study Relevance: Performance Measures |
Performance of Rehabilitated
Asphalt Concrete Pavements in the LTPP Experiments-Data Collected Through
February 1997(FHWA-RD-00-029)(3) |
- Nonwheel-path longitudinal
cracking was the most prevalent distress in the early period (SPS-5).
- Fatigue cracking was the least
observed distress (SPS-5).
- Nonwheel-path longitudinal
cracks exceeded wheel-path longitudinal cracks (general pavement study
(GPS)-6).
- GPS-6 data showed
that fatigue cracking and longitudinal cracking in the wheel path are
related. Specifically, the longitudinal cracking in the wheel path will
propagate or evolve into fatigue cracking with continued
traffic loading.
|
Rehabilitation of
Asphalt Concrete Pavements-Initial Evaluation of the SPS-5 Experiment (FHWA-RD-01-168)(4) |
- Four performance indicators
were established: fatigue cracking, transverse cracking, rutting, and IRI.
- Fatigue cracking occurred most
frequently on older sections.
- Transverse cracking occurred in
all but four of the projects, all of which were less than 7 years old.
- Older sections showed moderate
severity of transverse cracks even in a
no-freeze climate.
- Test sections with extensive
transverse and fatigue cracking had high IRIs.
|
LTPP Data Analysis:
Effectiveness of Maintenance and Rehabilitation Options Web Document 47 (Project 20-50(3/4))(5) |
- All SPS-5 overlay treatments reduced long-term
roughness relative to the nonoverlaid sections.
- The rutting data from the SPS-5 and GPS-6B
experiments indicated that on average, about 0.2 inches (6 mm) of rutting
developed in the first year after placement of an asphalt overlay of an
asphalt pavement.
|
Design Factors |
Performance of
Rehabilitated Asphalt Concrete Pavements in the LTPP Experiments-Data
Collected Through February 1997 (FHWA-RD-00-029)(3) |
- The nominal 5-inch (127-mm)
overlays generally showed better performance than the nominal 2-inch (5l-mm)
overlays, as expected (SPS-5).
- The thicker overlays generally
exhibited less cracking distress than the thinner ones but had little effect
on the occurrence of rutting and no apparent effect on roughness (SPS-5).
- The different type of mixtures
(virgin or recycled asphalt concrete (AC)) appeared to have the least effect
on performance of any of the factors included in this experiment (SPS-5).
- There was no
advantage to using virgin versus recycled mixtures in reducing the number of
transverse cracks.
- Compared to virgin
mixes, recycled AC mixtures resisted longitudinal cracking outside the wheel
path substantially better in at least five projects.
- Thicker pavement performed
better (GPS-6).
- The thickness of the pavement was
conversely correlated with the extent of nonwheel-path longitudinal cracks
(GPS-6).
- Neither the age nor the
condition of the pavement before the overlay seemed to be critical to
cracking extent (GPS-6).
- Thicker overlays resisted
rutting slightly better than thinner ones (GPS-6).
- AC mix properties were the most
significant factors to limit rutting (GPS-6).
- Thicker overlays offered a
slight advantage for roughness (GPS-6).
- GPS-6A (existing AC
overlays on AC pavements) data showed that overlay designs that provided
pavement structure consistent with traffic expectations can be expected to
perform well for more than 10 years.
|
Rehabilitation of
Asphalt Concrete Pavements-Initial Evaluation of the SPS-5 Experiment (FHWA-RD-01-168)(4) |
- Overlay thickness
did not appear to have a strong effect on the occurrence
of longitudinal cracking in the wheel path and rutting (5 years after
rehabilitation).
- There was no
apparent effect of overlay thickness on roughness based on these early
observations (5 years after rehabilitation).
- Age of overlay was
found to be the leading contributing factor to four of the six distresses
studied in the SPS-5 experiment (rehabilitation of AC pavements): fatigue
cracking, rutting, transverse cracking, and initial pavement smoothness.
|
LTPP Data Analysis:
Effectiveness of Maintenance and Rehabilitation Options (Project 20-50(3/4))(5) |
- Overlay thickness
and preoverlay roughness level were the two factors that most influenced the
performance of asphalt overlays of asphalt pavements in the SPS-5 experiment
with respect to roughness and fatigue cracking.
- No significant mean differences
were detected in long-term roughness, cracking, and rutting between recycled
mixes versus virgin mixes.
- No significant mean differences were detected in
long-term rutting between minimal versus intensive preparation or thin
versus thick overlays.
- Preoverlay cracking, age, and
accumulated traffic loads significantly correlated to the difference in
long-term cracking in nonoverlaid versus overlaid sections.
|
Reducing Flexible
Pavement Distress in Colorado Through the Use of PMA Mixtures(6) |
- Projects using modified HMA mixtures were found to
have lower amounts of fatigue cracking, transverse cracking, and rutting.
- The use of modified HMA
mixtures was found to extend the service life of HMA overlays by about 3
years, a 30 percent increase over the 10-year
design life.
|
Construction Factors |
Performance of
Rehabilitated Asphalt Concrete Pavements in the LTPP Experiments-Data
Collected Through February 1997 (FHWA-RD-00-029)(3) |
- The test sections that had
received intense surface preparation (patching and milling) prior to
placement of the overlays generally performed better than test sections that
had not. Reduced fatigue cracking, reduced longitudinal cracking in the
wheel paths, and reduced transverse cracking were observed on intensely
prepared sections.
- The amount of
transverse cracking was dependent on the original pavement condition before
overlay placement. The overlays placed on pavements classified in good
condition exhibited less transverse cracking than on pavements classified in
poor condition.
- No substantial difference was
noted between longitudinal cracking outside the wheel paths, rutting, and
roughness between the test sections with and without milling (SPS-5).
- Rutting was not affected by or
related to the condition of the original pavement or age of the overlay
(GPS-6).
- The condition of the original
pavement prior to overlay appeared to have little effect on the occurrence
of or increase in roughness (GPS-6).
- The amount of traffic affected
the growth of roughness (GPS-6).
|
Rehabilitation of
Asphalt Concrete Pavements-Initial Evaluation of the SPS-5 Experiment (FHWA-RD-01-168)(4) |
- Fewer or shorter transverse
cracks occurred on sections that had been milled.
- According to an analysis of
variance (ANOVA), milling depth had an important effect on the length of
transverse cracks.
- The IRI values of the overlay
were lower for the overlays placed over pavements in the fair category and
when the existing surface was milled before overlay.
|
LTPP Data Analysis:
Effectiveness of Maintenance and Rehabilitation Options (Project 20-50(3/4))(5) |
- Asphalt pavements overlaid when rougher tended to
have somewhat
more initial roughness after overlay than asphalt pavements overlaid
when smoother.
- There was no significant mean
difference in long-term roughness between overlays with minimal versus
intensive preoverlay preparation.
- No significant mean differences were detected in
long-term cracking between minimal versus intensive preparation.
|
Site Factors |
Rehabilitation of
Asphalt Concrete Pavements-Initial Evaluation of the SPS-5 Experiment(6) |
- The age of the overlay and the
climatic factors temperature and moisture had a
significant effect on fatigue cracking.
- More fatigue cracking occurred
on test sections in a climate with less precipitation but higher freeze
indices.
- Longer transverse cracks
occurred on the older pavements in areas with higher freeze indices.
- Freeze index had an effect on
the length of transverse cracks.
- The age of the overlay and
precipitation had an effect on rut depth. Sections with increased
precipitation had larger rut depths.
- The age of the overlay,
condition of the pavement before overlay placement, and surface preparation
or milling depth were important factors relative to the IRI values.
- Milling offered no consistent advantage
for resisting longitudinal cracking outside the wheel path during the early
life of an overlay.
|
LTPP Data Analysis:
Effectiveness of Maintenance and Rehabilitation Options (Project 20-50(3/4))(5) |
- Overlay age and average annual
precipitation had a significant effect on long-term rutting.
- A significant correlation was
detected between average annual precipitation and the difference in
long-term rutting in 2-inch (51-mm) versus 5-inch
(127-mm) overlays.
|
Publication |
Major Findings |
Current Study Relevance: Design Factors |
LTPP Data Analysis:
Effectiveness of Maintenance and Rehabilitation Options (Project 20-50(3/4))(5) |
- The effectiveness of the rigid pavement rehabilitation treatments in the SPS-6
experiment can be ranked from most to least effective with respect to IRI,
rutting, and cracking as follows: (1) 8-inch (203-mm) overlay of
cracked/broken and seated pavement, (2) 4-inch (102-mm) overlay of either
intact or cracked/broken and seated pavement with or without sawing and
sealing of transverse joints and with minimal or intensive preoverlay repair,
(3) concrete pavement restoration with diamond grinding, full-depth repair,
and joint and crack sealing, and
(4) concrete pavement restoration without diamond grinding but with
full-depth repair and joint and crack sealing.
- Subdrainage retrofitting, undersealing, and/or load
transfer restoration techniques did not produce significantly lower
long-term roughness levels compared to sections that received only diamond
grinding, full-depth repair, and joint and crack sealing.
|
Rehabilitation of
Jointed Portland Cement Concrete Pavements: Initial Evaluation and Analysis (FHWA-RD-01-169)(7) |
- The rehabilitation techniques in exposed
Portland cement concrete (PCC) involve restoration techniques other than
overlay including full-depth repair, diamond grinding, joint sealing, and
addition of retrofitted edge drains.
- If the prerehabilitated section has
significant roughness, diamond grinding should be considered or the section
will retain its roughness. Full-depth repairs do not remove significant
roughness from a jointed concrete pavement by themselves.
- Both routine and premium pavement preparation
treatments reduce the amount of transverse cracking immediately after
rehabilitation. Routine preparation treatment includes limited patching,
crack repair and sealing, and stabilization of joints. Premium preparation
treatment includes subsealing, subdrainage, joint repair and sealing,
full-depth repairs with restoration of load transfer, diamond grinding, and
shoulder rehabilitation.
- Premium pavement preparation with
diamond grinding reduces the amount of faulting to zero immediately after
rehabilitation.
- AC overlay of nonfractured PCC
rehabilitation technique involves applying varying degrees of preoverlay
repairs and placing an
AC overlay.
- The AC overlay of nonfractured PCC
reduces the roughness immediately after rehabilitation to a smooth level (5.28
ft/mi
(1.0 m/km)).
- The sections with AC overlay of
nonfractured PCC exhibit a faster increase in IRI over time than does the
fractured PCC.
- The sections with AC overlay of
nonfractured PCC exhibit a lower increase in IRI over time than do premium
preparation nonoverlaid PCC sections.
- The routine and premium preparation
sections with 4-inch (102-mm) AC overlays exhibited no reflective cracking
within the first year after construction.
|
Design Versus Built Variations |
Rehabilitation of
Jointed Portland Cement Concrete Pavements: Initial Evaluation and Analysis (FHWA-RD-01-169)(7) |
- Sites in South Dakota, Arizona, and California did
not meet the annual precipitation requirement for the climate they were
considered for.
- Sites in Tennessee, Oklahoma, and California did
not meet the freeze index requirement for the climate they were considered
for.
- Four sites fell short on the required age criteria.
- A total of 45 percent of sites did not have an AC
overlay thickness within the designed range.
|
Performance Measures |
LTPP Data Analysis:
Effectiveness of Maintenance and Rehabilitation Options (Project 20-50(3/4))(5) |
- The rutting data
from the SPS-6 (rehabilitation of jointed PCC pavements) and GPS-7B (new AC
overlays on PCC pavements) experiments indicate that on average, 0.24 inches
(6 mm) of rutting developed in the first year after placement of an AC
overlay of either an intact or a cracked/broken and seated concrete pavement.
This may be due to compaction of the AC overlay by traffic and appears to be
independent of the overlay thickness, mixture type, preoverlay preparation,
and preoverlay rutting level.
- No significant differences were
detected in cracking based on 8 years of data as follows:
- Between minimal (i.e., without milling)
and intensive (i.e., with milling) preoverlay preparation.
- Between sections with and sections without
sawed and sealed joints.
- Between 4-inch (102-mm) overlays with
sawed and sealed joints versus those over cracked/broken and seated
pavements.
- Between 4-inch (102-mm) and 8-inch (203
mm) overlays of cracked/broken and seated pavements.
- In 4-inch (102-mm) AC overlays of
intact slabs, no significant differences were detected in roughness based on
6 years of data
as follows:
- Between minimal and intensive preoverlay
preparation.
- Between sections with and without
sawing and sealing of
transverse joints.
- Between overlays with sawed and sealed
joints and overlays of cracked/broken and seated slabs.
- Among overlays of cracked/broken and
seated slabs, the 8-inch
(203 mm) overlays had significantly lower long-term roughness than the
4-inch (102-mm) overlays, as expected.
|
Publication |
Major Findings |
Current Study Relevance: Design
Factors |
The LTPP Experiment SPS-3
5-Year Data Analysis (FHWA-RD-97-102)(8) |
- Structural adequacy did not have a significant
effect on the performance of SPS-3 treatments.
- Thin overlay had a significant effect in rutting
and roughness reduction, while other treatment options were either slightly
effective or not effective.
|
LTPP Data Analysis:
Effectiveness of Maintenance and Rehabilitation Options (Project 20-50(3/4))(5) |
- In the SPS-3 thin overlay sections, pavement
age was the only factor studied that was found to be significantly correlated
to the rate of rutting.
- In the SPS-3 crack sealed and chip
sealed sections, average annual precipitation was the only factor studied
found to significantly correlate to the rate of rutting.
|
Analysis Approach |
The LTPP Experiment
SPS-3 5-Year Data Analysis (FHWA-RD-97-102)(8) |
- This report provides multiple regression models to
develop prediction models for cracking, rutting, ride quality, friction, and
pavement rating score.
|
Pavement Maintenance
Effectiveness (SHRP-H-358)(9) |
- This study developed a damage
modeling approach with an index varying between zero and 1. The index is
dependent on accumulated traffic/age, expected traffic/age to failure, and
the shape of the performance trend.
|
LTPP Maintenance and
Rehabilitation Data Review (FHWA-RD-01-019)(10) |
- This report documents a survival analysis of SPS-3
sites in the Southern LTPP region in 1999 to obtain life expectancy of each
treatment, effect of timing, and the benefit of treatment to the life span
of the pavement.
|
Treatment Performance |
LTPP Maintenance and
Rehabilitation Data Review (FHWA-RD-01-019)(10) |
- After 6 years of service, sections that received
maintenance when in poor condition had a probability of failure twice as
much as sections initially in fair or good condition.
- Sections in fair and good condition had about the
same probability of failure.
- The overall median survival times for thin overlay,
slurry seal, and crack seal were 7, 5.5, and 5.1 years, respectively.
- A median survival time for chip seal could not be
determined because fewer than 50 percent of these sections had failed at the
time of the analysis. Chip seals outperformed thin overlay, slurry seal, and
crack seal treatments with respect to controlling the reappearance of
distress.
|
LTPP Data Analysis:
Effectiveness of Maintenance and Rehabilitation Options (Project 20-50(3/4))(5) |
- In terms of roughness, rutting, and fatigue
cracking, the most effective of the maintenance treatments was the thin
overlay treatment, followed by the chip seal treatment, and then the slurry
seal treatment.
- The thin overlay treatment was the only one of the
four SPS-3 maintenance treatments to produce an initial small reduction in
roughness, and the only one of the four to have a significant effect on
long-term roughness, relative to the control sections.
- For the SPS-3 test sections, the thin
AC overlay treatment was the only one of the four treatments (thin AC
overlays, chip seals, slurry seals, and crack seals) that showed a
significant initial effect on rutting. Thin AC overlays also had the most
significant effect on long-term rutting control.
- For rougher pavements, there was some evidence that
chip seals and slurry seals also had some effect on long-term roughness,
rutting, and cracking relative to the control sections.
- Crack seals did not have any significance on
long-term roughness, rutting, or fatigue cracking.
|
Pavement Treatment
Effectiveness, 1995 SPS-3 and SPS-4 Site Evaluations National Report  (FHWA-RD-96-208)(11) |
- The thin AC overlay treatments
performed best after 5 years.
- In general, chip seal treatments
also performed well. Chip seal performance was best in the Southern region,
which has a predominantly wet no-freeze environment.
- The crack seal treatment
performed very well in wet freeze environments where the wide shallow
sealant reservoir was routed. Crack seal performance in the other two
regions was not as successful.
|
LTPP Pavement
Maintenance Materials: SHRP Crack Treatment Experiment  (FHWA-RD-99-143)(12) |
- The most cost-effective treatments for
crack seals are usually those consisting of rubberized asphalt placed in a
standard or shallow-recessed band-aid configuration. The standard recessed
band-aid method showed the longest estimated service life, followed very
closely by the shallow recessed band-aid method.
- For long-term crack-seal performance (5
to 8 years) under the condition where 0.1 to 0.2 inches (2.5 to 5.0 mm) of
horizontal crack movement occurred, a modified rubberized asphalt sealant
should be installed in either a standard or a shallow recessed band-aid
configuration.
|
Design Versus Built Variations |
LTPP Data Analysis:
Effectiveness of Maintenance and Rehabilitation Options  (Project 20-50(3/4))(5) |
- The review of construction problems and deviations
in the SPS-3 experiment illustrated that more than 40 percent of the sites
had problems in the application of maintenance treatments, mostly chip seal.
|
Treatment Timing |
Pavement Treatment
Effectiveness, 1995 SPS-3 and SPS-4 Site Evaluations National Report (FHWA-RD-96-208 (11) |
- The question of timing cannot
be resolved completely from the visual observation of the SPS-3 sites, but
indications are that earlier application of the preventive maintenance
treatments provides greater benefits than later application.
|
Publication |
Major Findings |
Current Study Relevance: Performance Measures |
LTPP Data Analysis:
Relative Performance of Jointed Plain Concrete Pavement with Sealed and
Unsealed Joints (NCHRP Web
Document 32 Project 20-50(2))(13) |
- Joint spalling was quantified
by several measures, including percentage of joints spalled within a
pavement section, total length of joint spalling, percentage of total joint
length spalled, and percentage of individual joint length spalled. In
addition, weighted measures were used that take into account the severity of
joint spalling as characterized by low-, medium-, and high-severity joint
spalling.
- The faulting
measure employed in most previous analyses of LTPP concrete pavement
performance is average joint faulting, as measured in the outer wheel path. In
addition, average absolute faulting was introduced in the study to account
for negative faulting (the approach slab edge being lower than the leave
slab edge). Absolute average faulting is calculated as the arithmetic
average of the absolute values of the individual joint faulting
measurements.
- An index of weighted sealant
damage was developed to quantify overall transverse joint sealant condition
as a weighted average of the numbers of joints within the section with low,
medium, and high sealant damage ratings.
|
Treatment Performance |
LTPP Data Analysis:
Relative Performance of Jointed Plain Concrete Pavement with Sealed and
Unsealed Joints (NCHRP Web
Document 32 Project 20-50(2))(13) |
- Based on 5 years of data collected at the five test
sites built in Arizona, Colorado, and Utah (all in the dry region), the
effects of sealed and unsealed joints on spalling were similar.
|
Pavement Treatment
Effectiveness, 1995 SPS-3 and SPS-4 Site Evaluations National Report (FHWA-RD-96-208)(11) |
- SPS-4 sealed joint sections performed better than
unsealed sections.
- Unsealed joints also had significantly more joint
spalling than the sealed joint sections.
- Unsealed joints in the control sections contained
significantly more debris than sealed joint sections.
|
Concrete Pavement
Maintenance Treatment Performance Review: SPS-4 5-Year Data Analysis (FHWA-RD-97-155)(14) |
- No significant differences were
identified between the control sections (unsealed) and the sealed-joint or
undersealed (slab stabilization) sections. This observation was based on the
32 SPS-4 sites.
- Based on 5 years of data collected in Arizona,
Colorado, Nevada, and Utah, no significant differences in initial pavement
smoothness were identified among the three treatments consisting of sealed,
undersealed, and unsealed joints in the SPS-4 experiment.
- In the analysis of SPS-4 performance through 1995,
no significant differences were detected in IRI or joint
faulting between sealed-joint and unsealed-joint sections.
|
Design and Construction
of PCC Pavements, Volume 1: Summary of Design Features and Construction
Practices that Influence the Performance of Pavements (FHWA-RD-98-052)(15) |
- Neither presence nor type of sealant was found to
be significant in the regression analysis of JPCP joint faulting in the
GPS-3 experiment.
|
Common Characteristics
of Good and Poorly Performing Pavements (FHWA-RD-97-131)(16) |
- In statistical analyses of GPS-3 performance data,
neither sealant presence or sealant type was found to be a significant
variable in the prediction of dowelled or undowelled joint faulting in JPCP.
|
LTPP Pavement
Maintenance Materials: SPS-4 Supplemental Joint Seal Experiment (FHWA-RD-99-151)(17) |
- A comparison of joint sealant types
among the SPS-4 supplemental test sections built in Arizona, Colorado,
Nevada, and Utah between 1990 and 1995 showed that silicone seals outperformed
the other two treatments for transverse joint seals (compression seals and
hot pours).
|
Publication |
Major Findings |
Current Study Relevance: Review of Previous Studies |
Optimal Timing of
Pavement Preventive Maintenance Treatment Applications (NCHRP Report 523)(18) |
- Several studies researched the
issue of optimum timing of the preventive maintenance treatments to achieve
best maintenance effectiveness. These included earlier studies of SPS-3 and SPS-4
experiments and State transportation department studies in Arizona, Iowa,
Montana, Texas, and
South Dakota. None of these studies was successful in identifying the
optimum timing of preventive maintenance treatments.
|
Treatment Timing |
Optimal Timing of
Pavement Preventive Maintenance Treatment Applications (NCHRP Report 523)(18) |
- A methodology was developed to determine the
optimal timing for the application of preventive maintenance treatments to
flexible and rigid pavements. The methodology was based on the analysis of
pavement performance and costs associated with maintenance treatment. It
assessed the effectiveness of a particular preventive maintenance treatment
in terms of both the benefit it provided and the cost required to obtain
that benefit. The benefit was defined as the quantitative influence on
pavement performance as measured by pavement condition factors. Condition
indicators may be expressed by such measures as IRI, present serviceability
index, or other custom-defined measure of pavement performance. The optimum
application of a preventive maintenance treatment occurred at the point at
which the benefit per unit cost was greatest.
|
SPS-3 and SPS-4 Data Applicability |
Optimal Timing of
Pavement Preventive Maintenance Treatment Applications (NCHRP Report 523)(18) |
- One of the case studies conducted under NCHRP
Project 14-14 was a review of the data from LTPP SPS-3 and -4 experiments.(19) The conclusion from that case study was that LTPP data at that time could
not be used to conduct the analysis of optimal timing. The reasons provided
in the report include the counterintuitive performance trends, no
improvement in performance as a result of treatment application, and not
enough sections with treatments applied at different ages that exhibited the
expected trends to support the analysis.
|
Publication |
Major Findings |
Preliminary Evaluation
and Analysis of LTPP Faulting Data- Final Report (FHWA-RD-00-076)(20) |
- Data analysis was performed to
determine the usefulness of joint faulting and related data in identifying
factors that affect joint faulting. As part of this study, an assessment of
data availability and data quality was performed for the
SPS-4 experiment. Data for a total of 422 jointed concrete pavement sections
were available in the LTPP Information Management System (IMS) database at
the time of the study. Of these, only 307 sections had records in the
faulting data table MON_JPCC_FAULT, for a total of 24,108 records.
|
Rehabilitation of
Asphalt Concrete Pavements: Initial Evaluation of the SPS-5 Experiment (FHWA-RD-01-168)(4) |
- The data availability and
completeness were good overall for the SPS-5 experiment with two exceptions:
traffic and materials test data. These data deficiencies should be addressed
before a comprehensive analysis of the SPS-5 experiment is conducted. Both
of these data elements must be collected in order for the SPS-5 experiment
to meet the expectations for calibrating and validating mechanistic models.
|
Rehabilitation of
Jointed Portland Cement Concrete Pavements: SPS-6-
Initial Evaluation and Analysis (FHWA-RD-01-169)(7) |
- Data availability and
completeness for the SPS-6 experiment are good overall, but some data, such
as traffic, climatic, and materials data, were not yet available in the IMS
database. Three of the 14 sites were still relatively new and, therefore,
did not have much data available. It was believed that the information was
collected and in the process of being entered into the IMS database.
|
LTPP Data Analysis:
Effectiveness of Maintenance and Rehabilitation Options (Project 20-50(3/4))(5) |
- The data used in this research
were the data available at all quality levels in LTPP data release 11.5
dated June 13, 2001.
- Efforts to analyze the SPS-3
experiment were hampered by data availability problems and the short times
in which the treatments had been in service.
- In both the SPS-5 and -6
experiments, the long-term rutting data were so erratic that analysis of
long-term trends was problematic.
|
LTPP Maintenance and
Rehabilitation Data Review (FHWA-RD-01-019)(10) |
- This publication provides a
review of maintenance and rehabilitation data elements across all the
experiments for data completeness and anomalies. The test sections were
divided into three categories based on surface type: HMA, jointed concrete
pavement, and continuously reinforced concrete pavement. The study was based
on the 1999 third quarter LTPP data release. There were a total of 757 type
sections, including SPS and GPS, for which maintenance and rehabilitationÂ
techniques have been documented in the database.
|