Pavement Distress
and Drainage
Surveys
Purposes of Drainage Survey
• Identify moisture-related distress
• Document drainage conditions of
pavement
• Assess condition and effectiveness of
edge drains (if present)
Pavement Distress
• Fundamental performance indicator
• Characterized by:
– Type
¾What?
– Severity
¾How Bad?
– Extent
¾How Much?
Purposes of Distress Survey
•
•
•
•
•
•
•
Document pavement condition
Identify types of distress
Group areas of similar performance
Gain insight into causes of deterioration
Identify additional testing needs
Identify possible rehabilitation treatments
Identify repair areas and quantities
Project-Level vs. NetworkLevel Surveys
• Project-level surveys
– Specific projects
– Identify deficiencies
– Identify appropriate rehabilitation
• Network-level surveys
– Selected sections or samples
– Identify projects for rehab
– Planning and allocation of funding
Distress Identification
Manual
• Standardized distress definitions
– In house
– Or national
• Benefits
– More consistent calls
– Better communication
– Improves pavement management (PMS)
– Degree of sophistication
¾Project-Level
¾Network-Level
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LTPP Distress
Identification Manual
Fatigue Cracking
• Research-oriented
• All pavement types
• Distress definitions
– Description
– Severity levels
– How to measure
• Schematic drawings
• Photographs
• Data collection forms
Fatigue Cracking
Fatigue Cracking
Potholes
Transverse Cracking
2
Transverse Cracking
Transverse Cracking
Transverse Cracking
Transverse Cracking
Block Cracking
Block Cracking
3
Rutting
Permanent
Deformation
• Rutting
• Shoving
• Corrugations
Assessing the Problem
Assessing the Problem
Types of Rutting
Four Types of Rutting
• Mechanical deformation
• Mechanical deformation
– Result of insufficient structural capacity
• Plastic flow
– Usually accompanied with fatigue cracking
• Consolidation
• Surface wear
Mechanical Deformation
Assessing the Problem
Types of Rutting
original
profile
• Plastic flow
asphalt layer
subgrade
deformation
Weak Subgrade Or Underlying Layer
– High pavement temperatures
– Materials and mixture design
¾rounded aggregate
¾too much binder and/or filler
– Insufficient VMA
4
Plastic Flow
Assessing the Problem
Types of Rutting
• Consolidation
– Insufficient compaction
¾too few roller passes
¾material cooling prior to achieving target
density
original
profile
Weak Asphalt Layer
shear plane
Consolidation
¾high fluid content (asphalt, moisture, dust)
contribute to tender mixes
Assessing the Problem
Types of Rutting
original
profile
• Surface wear
Wheel path consolidation
– Wear from chains and studded tires
Inadequate Compaction
Raveling
Bleeding
5
Common HMA Distresses
Distress
Type
Traffic/
Load
Fatigue Cracking
Block Cracking
Trans/Long Cracking
Potholes
Patch/Patch Deter.
Rutting/Shoving
Bleeding
Weathering/Raveling
X
X
X
X
X
Climate/
Materials
X
X
X
X
X
Pavement Distress Surveys
• Automated (network-level)
– Specialized vehicle at highway speeds
– Distress later interpreted in office
– Commonly done for PMS
– Will trigger rehab projects
• Manual (project-level)
– Walking over pavement
– Pavement distresses recorded
Manual Distress Surveys
• Components of project-level evaluation
– Pre-survey activities
– Initial windshield survey
– Detailed distress survey
– Photographs/videotapes
– Drainage survey
Windshield Survey
Access:
• Overall rideability
• Uniformity of distress in
project limits
• Identify additional testing
Pre-Survey Activities
•
•
•
•
•
Project design and location data
Data collection forms
Distress identification manual
Information from previous surveys
Traffic control arrangements
Walking Survey
• Two-person crew
• Record and map all
pavement distress
• Traffic control
6
SHRP Distress Form
SHRP
Distress
Form
Symbols
SHRP Distress Form
Photographs/Videos
• Document condition
• Capture typical distresses
• Communication
Components of Drainage
Surveys
Drainage Surveys
• Conducted as part of manual surveys
• Determine if moisture is affecting the
performance of the pavement
•
•
•
•
•
Topography and cut/fill
Pavement and shoulder slopes
Condition of ditches
Condition of drainage outlets or inlets
Effectiveness of edge drains
7
Condition of Outlets
Video Inspection
Topography and
Condition of Ditch
Evaluation of Distress
Survey Results
• Summarize distress data for project
• Prepare strip charts
– Observe performance over project
– Evaluate with other collected data
• Prepare historical performance charts
Silty Clay
High Traffic
Granular
Silty Clay
Low Traffic
Condition 1 Condition 2 Condition 3
FC
(%)
Severity
Low
Medium
High
Performance Trends
Fatigue Cracking, % Area
Fatigue Cracking Strip Chart
Section 1
Section 2
Section 3
1985
1990
Year
1995
2000
Distance Along Project
8
Questions, Comments?
Nondestructive Testing and
Data Analysis
Don’t forget to check drainage!
Introduction
Pavement Responses Under Load
ƒ NDT - Valuable engineering
Axle
Load
– Variability
– Structural adequacy (in situ pavement)
ƒ Fast and produces repeatable results
ƒ Used by most states for project and
some network level evaluation
Surface
ε SUR
Base/Subbase
δ SUR
ε SUB
Subgrade Soil
Strong vs. Weak Pavements
NDT Load
“Strong”
Pavement
Types of NDT Equipment
ƒ Static
ƒ Vibratory
ƒ Impulse
ƒ Surface wave propagation
“Weak”
Pavement
Δ
9
Vibratory Equipment
(steady state dynamic)
“Static” Load Devices
ƒ Benkelman
Beam
Dynaflect
Road Rater
ƒ California Traveling Deflectometer
ƒ La Croix Deflectograph
Typical FWD Equipment
Dynatest
KUAB
Rolling Wheel Deflectometer
Other:
Phonix
JILS
5/29/2006
Project Variability
ƒ Distress
ƒ Subsurface variations
ƒ Random variability
Maximum Deflection (mm)
Pavement Factors
0.75
0.50
0.25
0
0
1000
2000
3000
Distance Along Roadway (m)
10
Climatic Factors
ƒ Temperature
ƒ Moisture
ƒ Frost penetration
Conducting NDT Surveys
ƒ Used as a follow-up to distress survey
ƒ Accurate layer thickness is essential
ƒ Time of testing
– Seasonal (year-round) testing is desirable
– Time that best represents effective year-round
condition is also good
Seasonal Variation in
Pavement Deflection
Deflection
Period of
Strength Loss
Period of Rapid
Strength Recovery
Uses of Deflection
Testing Data
ƒ Uniformity of project
– Design sections for rehabilitation
Period of Slow
Strength Recovery
Period of
Deep Frost
– Locations for sampling / testing
ƒ Backcalculate layer moduli
– Pavement layers
– Subgrade soil resilient modulus
Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov
Time
Nondestructive Testing and
Data Analysis
ƒ Questions?
Roughness and
Surface Friction
Testing
5/29/2006
11
Roughness Surveys
Why is it important to assess
roughness and friction?
• Both affect “functional” performance
• Roughness leads to increases in:
f
Vehicle operating costs
f
User delay
f
Accidents
f
User dissatisfaction
Definition of Roughness
Purpose of a
Roughness Survey
• Surface Deviations that affect ride
• Identify areas of severe roughness
• Caused by:
• Roughness between projects
f
Built-in surface irregularities
f
Traffic and environment
• Gauge benefits rehabilitation
Ride Quality Surveys
Roughness Survey Types
1.Ride quality surveys (serviceability)
f Subjective
f Simple
method
assessment tool
2.Objective roughness surveys
f Quantitative
f Various
unbiased method
of equipment are available
Serviceability
• Subjective
f
Direct measurement of user’s perception
• Measurement scale
f
Zero (very poor) to Five (very good)
f
Working range: 1.5 to 4.5
• Trigger levels for rehabilitation
• Correlations with other roughness indices
12
Pavement Condition
Pavement Condition
5
Pavement
Performance
0
Time or Traffic
Pavement Condition
Rating 1-5
Pavement Condition Index
Pavement Condition Index
5
4.5
2.0
1.5
0
Time or Traffic
Pavement Condition
Rating 1-5
Pavement Condition
Rating 1-5
13
Roughness Measuring
Equipment
• Response-Type Road Roughness
Measuring Systems (RTRRMS)
f Maysmeter
f PCA Roadmeter
f BPR Roughometer
• Inertial Road Profiling Systems (IRPS)
f ICC Profiler
f K.J. Law Profilometer
f South Dakota Profiler
Response-Type Systems
Maysmeter
Response-Type Road Roughness
Measuring Systems (RTRRMS)
• Measure vehicle response
• Advantages
Low initial and operating costs
Ease of operation
f High measuring speeds
• Disadvantages
f
f
Output sensitive to vehicle
characteristics
f Requires frequent calibration
f
Inertial Road Profiling Systems
Equipment (IRPS)
• Measure actual pavement profile
• Advantages
f
Relatively accurate and repeatable
profile measurements
Used to calibrate RTRRM systems
• Disadvantages
f
Inertial Profiler Systems
f
High capital and operating expenses
f
Complexity of systems
International Roughness Index
(IRI)
• Current roughness measurement standard
• Correlates to RTRRM systems
• Scale: 0 to 20 m/km (0 to 1267 in/mi)
• 2 m/km (125 in/mi) is typical break point
between rough and smooth pavements
• Standard for FHWA HPMS Database
14
Roughness Data Variability
• Seasonal and daily environmental effects
Surface Friction Testing
• Lateral positioning
• Differences in operator practice (betweenoperator variability)
• Differences between equipment devices
(between-device variability)
f
Manufacturing differences
f
Calibration problems
Definition of
Surface Friction
• Force developed at pavement-tire
interface that resists sliding
Purpose of a Surface
Friction Survey
• Assess safety concerns
• Influenced by:
f
Surface texture
f
Surface drainage (cross-slope)
Hydroplaning
f
Wet weather accidents
• Target testing in areas of poor surface
condition:
How do you adequately assess
surface frictional characteristics?
• Historical method—Measure friction
directly (“skid number”)
• Recent research indicates that “surface
texture” MUST also be considered
f
f
Smooth macrotexture (polishing or
inadequate finishing)
f
Inadequate pavement cross slope
What is surface texture?
• Characteristics that contribute to surface
friction
• Microtexture – individual pieces of aggregate
• Macrotexture
f
General coarseness of pavement surface
15
Friction Survey Measurement
Equipment Types
Friction Measuring Devices
Locked-Wheel Trailer
• Locked-wheel testers
• Side force testers (Mu Meter, SCRIM)
• Fixed slip testers (Gripster)
• Variable slip testers (Norsemeter ROAR)
Note: These devices do NOT measure texture!
Friction Measuring Devices
Examples of Other Devices
Surface Texture Measuring
Devices
• Volumetric (“Sand Patch”) method
• Outflow meter
• Circular track meter (CTMeter)
• High-speed laser-based devices
(ROSAN, most laser-based profilers)
SCRIM
(side force tester)
Mu Meter
(side force tester)
Norsemeter ROAR
(variable slip tester)
Surface Texture Measurement
Sand Patch Method
Surface Texture Measurement
High-speed Laser-Based Devices
High-Speed Inertial
Profilers
ROSANv
16
International Friction Index
(IFI)
• Incorporates simultaneous measurements
of friction and macrotexture
f
Speed constant (Sp)
f
Friction number (F60)
Roughness and Surface
Friction Testing
• Questions?
• Becoming friction measurement standard
• Modern high-speed measuring equipment
measure IFI directly
17