1. Influence of Pavement Condition on Project Selection
Session 3
Influence of Pavement Condition on Project Selection
This presentation describes key distress types in both flexible and rigid pavements and examines the suitability of the distresses to preventive maintenance treatments. For example, what are the types of distresses that can be corrected by preventive maintenance treatments? Are these distresses all low severity? Is a pavement still be a candidate for preventive maintenance if medium-severity distresses are visible? Is there a level below low severity that could be identified? Should such treatments be applied to pavements that have not yet developed any distress?
Another key topic covered in the presentation is the way that the distresses are identified. Do typical condition survey methods provide information relevant for preventive maintenance programs? How do preventive maintenance survey needs differ from pavement management needs, or are they the same?
It is likely that in addition to pavement condition, the engineer must have additional knowledge about the pavement, including construction and performance data on the pavement. From where does this information come? Some may be obtained through records review or perhaps a pavement management database. However, one of the most important sources of information on pavement condition and the performance of maintenance and rehabilitation treatments is from maintenance/field personnel. In addition to taking advantage of their insights, interaction with this group helps to ensure buy-in of the pavement preservation concept.

2. Learning Objectives
Upon completion of this module, you will be able to:
Define pavement condition and describe typical pavement survey types
Identify common HMA and PCC distress types
These objectives are self-explanatory. Spend a few minutes highlighting some of the key points.

3. Learning Objectives (continued)
Describe the typical progression of deterioration for HMA and PCC pavements
Describe the effect of preventive maintenance on the typical progression of pavement deterioration

4. Learning Objectives (continued)
Describe the importance of pavement condition survey data in developing preventive maintenance guidelines

5. Determining if a project is a “good candidate” for PM
No structural failures
Minimal distress (extent and severity)
Relatively young in age
Few historical problems with similar projects
What do you need to know to determine if a particular project is a good candidate for PM? What are the characteristics of pavements that you would consider “good” candidates for preventive maintenance? What do we need to know to make this decision? (Ask the audience for some help in determining a list of items. Some examples of pavement characteristics are shown on this slide. Possibly make a list on a white board).
After a list of pavement characteristics has been determined, try and get the audience to interpret these characteristics and really focus in on what we need to know to determine if a pavement is a good candidate for PM.
We really need to know two things to make an educated decision about whether or not a given project is a good candidate for preventive maintenance (i.e., we are trying to determine where the pavement is on its pavement performance curve.)
We need to estimate the current “condition” of the pavement (the next slide discusses what we mean by “condition”).
We need to estimate the expected “future performance” of the pavement.
Estimate pavement condition and future performance!

6. What pavement characteristics indicate pavement condition?
Visible performance indicators
Functional indicators
Structural indicators
Non-Visible defects
Environmental effects on materials
Load-related damage
First, let’s define what we mean when we say pavement “condition.” Typically a discussion of pavement condition is thought of what you can see on the pavement surface. But as we have indicated, what you don’t see can be more or as important in determining where the pavement is on its deterioration curve.
Visible performance indicators are those functional and structural indicators that are 1) visible on the surface, and 2) measurable.
Functional performance is ride and safety. Aspects of ride quality include smoothness and noise; safety includes friction, removal of standing water. What are some indicators of pavement functionality? Rough ride, wet weather accidents, standing water, noise. Ride quality, surface friction, and surface drainage.
Structural performance refers to the load carrying ability of the pavement. We can look at this indirectly by measuring the pavement response to loads or by testing the overall strength of the pavement or the strength of its individual layers. We also see signs of a pavement’s structural capacity in the distresses visible at the pavement’s surface. Distress (cracking and rutting) and surface deflections.
However, pavements begin to deteriorate long before they show any visible distress. That is, environmental conditions (temperature cycles and moisture infiltration) and repeated load applications cause incremental damage to pavement layers. This cumulative damage eventually results in visible pavement distress.

7. Estimating Future Performance Pavement Performance Indicators
Preventive
Maintenance
Good
Typical Pavement
Performance Curve
Pavement
Condition
(Functional or
Structural)
When we talk about estimating pavement “performance,” what we are really interested in is determining where the pavement is on its expected pavement performance curve. In general, pavements deteriorate (functionally and structurally) along some type of curve which starts at good and ends up in poor condition over time. Although the timing and rate may be different from one type of deterioration to another, the overall S-shape of the curve remains the same.
To determine if a pavement is a good candidate for PM, we really need to estimate the pavement’s remaining life (time until required rehabilitation). We know there is a window of opportunity in which preventive maintenance is effective,so it is important to estimate where on the performance curve a pavement is when considering the application of PM. If it is too early or too late, we will not see the maximum benefit.
Poor
Time (Years)

8. How do you determine a pavement’s true condition?
Conduct surveys
Type, amount, and severity of distress/deficiencies
Identify poor PM candidates
Additional information / historical records
Engineering judgment
How do you determine a pavement’s “true condition?” That is, how do you determine where a pavement is on its performance curve.
Distress Data from Surveys
Look at current visible distress data. There are a lot of other types of distress that could be visible on a pavement. Examples include the following:
Material-related problems (reactive aggregate or D-cracking in PCC; bleeding in asphalt)?
Subgrade softening/moisture-related damage (pumping and faulting in PCC; rutting in HMA)?
Traffic-related surface problems (polishing)?
Do these other visible distresses help determine whether or not a pavement is a good candidate for preventive maintenance? Yes.
Are pavements that contain any other distress type excluded from consideration for preventive maintenance? The answer from the audience should be “it depends?” On what does it depend? Distress type, severity, extent, estimated cause, etc. all help decide if a particular project is a good candidate for PM.
The type, amount, and severity of distress/deficiencies will typically give indications of the underlying problems. Identifying deficiency causes will help exclude pavements from consideration for preventive maintenance.
What if your pavement is not showing any visible distress? Is it a good candidate? Most likely “Yes.” What types of information would you need to estimate where such a pavement on its deterioration curve. Historical records (i.e. age, material quality, design, etc.) Past performance of similar pavements in a similar climate.
Additional Information
Other sources of information are used to develop an understanding of how a given pavement is expected to perform.
Engineering Judgment
Finally, there is no straight forward answer at this point. Engineering judgment must be used to determine this “window of opportunity” for preventive maintenance. It is important to note that although we don’t know the specific “indicators” for preventive maintenance, or the optimum timing, we do know what we can prevent, and how PM treatments generally influence pavement performance.

9. What techniques are used to assess pavement condition?
Visual distress surveys
Roughness surveys
Friction surveys
Drainage evaluation
Shoulder surveys
Deflection testing
With these performance indicators in mind, what types of field surveys can be used to assess these performance conditions?
Contrast project level with network level. In PMS, these are project level surveys, done when the network level survey has triggered potential projects. All of these survey types give useful information when deciding on whether or not to apply preventive maintenance, as well as when selecting appropriate PM techniques.
Visual distress surveys give an indication of current functional and structural conditions. Type, severity, and extent of visible distress is recorded. The visible distress types give an indication of .
Roughness and friction surveys are functional-related.
Drainage evaluations can be helpful in preventing structural problems.
Deflection testing can be used to provide information regarding the structural condition at specific points.

10. Interpreting Survey Results
Helps identify mechanisms causing distress (i.e., functional vs. structural)
Determines when PM is not an option
Speaks of urgency
Identifies which treatments are appropriate and which are not
Affects the type of treatment chosen
This slide summarizes the role that surveys play in determining appropriate preventive maintenance. Make the point that surveys actually tell what pavements can be “excluded” from PM consideration. If visible distresses are observed, the surveys can 1) tell if PM is still appropriate, 2) help determine underlying causes of visible distress, 3) determine if any current conditions can be slowed or corrected with PM treatment applications.
Also, stress that if you don’t see distress, it is likely that this pavement is a good candidate for PM. PM is much more effective on pavements in good condition. This is especially important since the remainder of this session focuses on distress. You should make the point that distress is not the sole driver of preventive maintenance, however, distress surveys do give a lot of important information about the condition of a pavement section.
Also stress the point that even though SHA’s are using the same treatments for “routine” and “preventive” maintenance, PM has a different focus.

11. Additional Information Needs Design/Construction Records
Design life
Structure
Materials
Traffic
Environment
Construction quality
Construction temperatures
The fact that this session is entitled Characterizing Pavement Condition implies that there are more aspects to this important activity than just gathering and compiling pavement distress data. This slide provides an indication of some of the additional data needs which can be obtained from existing design and construction records. When combined with compiled data from the distress survey, this information provides a sound basis for the selection of an appropriate preventive maintenance treatment.

12. Additional Information Needs (continued)
Data from field/maintenance personnel
Maintenance history
Performance of similar designs/treatments
Data from PMS or planning
If possible, it is also useful to work directly with field (construction) staff and other preventive maintenance personnel to develop a sense of the maintenance history of various projects what treatments have performed the best. Again, this information should complement the data from the distress surveys and help provide for a better preventive maintenance treatment selection.
Reviewing PMS or Planning data can help identify the most appropriate/effective schedule for the application of preventive maintenance.

13. Common Distress Types HMA PCC
Pavement deterioration manifests itself in many forms of distress. This course addresses these distresses according to the two main types of pavement in which they are prevalent.
HMA
PCC

14. Typical HMA Pavement Distresses
Fatigue cracking
Block cracking
Edge cracking
Longitudinal cracking
Reflection cracking
Potholes
Rutting
Bleeding/flushing
Raveling/weathering
Lane-to-shoulder drop-off
Roughness
Surface friction loss
Moisture damage
Stripping
Shoving
For HMA pavements, these represent the key types of distress. For many of these forms of distress, there is a preventive maintenance action that is feasible up to a certain level of severity and/or extent.
HMA

15. Typical Rigid Pavement Distresses
Blow-ups
Transverse cracking
Longitudinal cracking
Corner breaks
Durability cracking
Transverse joint faulting
Joint spalling
Joint seal damage
Loss of fines (pumping)
Friction loss
Map cracking and scaling
Roughness
For rigid pavements, these represent the key types of distress that affect both the structural and functional performance. Some of these distresses (e.g., blow-ups and corner breaks), even at there lowest levels of severity, preclude the use of preventive maintenance treatment treatments.
PCC

16. Progression of Pavement Deterioration
In order to apply appropriate PM at the optimal timing, one must first have a good understanding of the typical progression of pavement deterioration for both HMA and PCC surfaced pavements.
What must be stressed is that no matter how well-defined and well-constructed a pavement is, it will deteriorate over time as a function of repeated climatic cycles and traffic-related applications.
When trying to determine appropriate PM, it is important to ask yourself “How do I expect my pavements to perform?” You should have a feel for the typical performance of a pavement in your state given a particular location (climate) and traffic.
Point out that variation is great in performance due to changes in many characteristics: environment, design, construction, etc.
PCC
HMA

17. HMA Pavement Deterioration Catalysts of Deterioration
Traffic
Environment / Aging
Material problems
Water infiltration
Shown here are the four general causes of deterioration in HMA pavements.
HMA

18. Primary HMA Deterioration Initial Mechanisms of Deterioration
Environment /
Aging
Material /
Mix
Load /
Traffic
Asphalt
Hardening
Various Changes
Plastic Deformation
Surface wear
The general causes of deterioration (shown on the last slide) influence pavement performance in different ways.
Traffic loadings typically lead to plastic deformation.
Traffic applications (tire/pavement interaction) cause a wearing of the surface.
Environmental and aging effects cause the oxidation (hardening) of the asphalt.
HMA material or mix problems can lead to various different types of distress.
HMA

19. Primary HMA Deterioration Load-Related Distresses
Rutting
Fatigue Cracking
Plastic
Deformation
These are build slides that show the progression of load distresses in HMA pavements.
What distresses do you see?
HMA

20. Primary HMA Deterioration Traffic-Related Distresses
Polishing
Surface Wear
An additional traffic-related distress involves the polishing of the surface which leads to friction loss. Bleeding can also lead to friction loss.
Friction Loss
HMA

21. Primary HMA Deterioration Environment/Aging-Related Distresses
Block Cracking
Raveling/Weathering
Asphalt Hardening
This is also a build slide.
HMA

22. Primary HMA Deterioration Material/Mix-Related Distresses
Material Problems
Bleeding can also lead to loss of friction.
Bleeding/Flushing
Friction Loss
HMA

23. Secondary HMA Deterioration Influence of Moisture Infiltration
Cracks +
Moisture
Infiltration
Deteriorated Cracks
Breakdown of Existing Cracks
This build slide shows the progression of deterioration from moisture infiltration.
One cause of moisture infiltration into existing cracks causes the breakdown of existing cracks. This leads to:
Increased roughness.
Allows more water to enter pavement.
HMA

24. Secondary HMA Deterioration Influence of Moisture Infiltration
Cracks +
Moisture
Infiltration
Potholes
Loss of Fines (Pumping)
Lane-to-Shoulder Drop-off
Edge Cracking
Subgrade Softening
HMA

25. PCC Pavement Deterioration Catalysts of Deterioration
Load/Traffic
Environment and material problems
Poor construction quality
Water infiltration
Incompressibles in joints
Here are general categories of PCC pavement deterioration. We will look at each one in more detail.
PCC

26. PCC Pavement Deterioration Initial Mechanisms of Deterioration
Environment /
Materials
Construction
Quality
Load /
Traffic
Joint Problems
Joint and Surface Problems
Slab Fatigue
Surface Wear
PCC

27. PCC Pavement Deterioration Load-Related Distresses
Loads
Transverse Cracking
Slab Fatigue
The typical load-related distress on PCC pavements is transverse fatigue cracking.
PCC

28. PCC Pavement Deterioration Traffic-Related Distresses
Polishing
Surface Wear
Polishing and/or rutting be caused by studded tire and chain wear in some states.
Friction Loss
PCC

29. PCC Pavement Deterioration Env./Material-Related Distresses
Environment/ Materials
Durability (“D”) Cracking
Joint Seal Damage
Joint Problems
PCC

30. PCC Pavement Deterioration Construction-Related Distresses
Poor Construction Quality
Longitudinal Cracking
Map Cracking
Scaling
Joint and Surface Problems
PCC

31. PCC Pavement Deterioration Influence of Moisture Infiltration
Cracks +
Moisture
Infiltration
Deteriorated Cracks
Breakdown of Existing Cracks
PCC

32. PCC Pavement Deterioration Influence of Moisture Infiltration
Cracks/Joints +
Moisture
Infiltration
Loss of Fines (Pumping)
Corner Breaks
Transverse Joint Faulting
Subgrade Softening
PCC

33. PCC Pavement Deterioration Influence of Incompressibles
Cracks/Joints +
Incompressible Material
Joint Spalling
Blow-Ups
PCC

34. Impact of Preventive Maintenance on Pavement Deterioration Progression
What do you think the implications of PM are on pavement performance? We have looked at load-, environmental-, material-, and construction-related problems. Are all of these preventable with PM? Obviously not. It depends on the mechanism. Preventive maintenance is not appropriate for all discussed distress mechanisms.

35. How can the application of preventive maintenance treatments influence the typical pavement deterioration progression?

36. What are the overall objectives of effective preventive maintenance?
Preserve investment
(Structural considerations)
Maintain high level of service (LOS)
In general terms, preventive maintenance can be seen to have two different overall objectives:
Preserve the investment (minimize structural failures and extend the structural life of the pavement), and
Maintain a high level of service for the pavement surface (maintain acceptable smoothness and surface friction). A secondary objective of maintaining a high LOS is improving public perception. Smoother roads with less visible distress result in a better image of the managing agency.
Are there other objectives?
Another way of looking at these objectives is how they influence costs.
Why are we interested in “preserving the investment?”
Because we are interested in minimizing the Agency costs associated with maintaining an acceptable level of service.
Why are we interested in “maintaining a high level of service for the pavement surface?”
Maintaining the minimum level of service not only focuses on minimizing the Agency costs, it is also important to provide a smooth and safe roadway that in turn minimizes the costs incurred by the User (these include vehicle operating costs [VOC], accident costs, and discomfort costs).
We will now briefly look at how preventive maintenance directly accomplishes these two goals.
(Functional considerations)
Other objectives?

37. How is PM used to preserve the investment?
Keep water out!
Reduce infiltration
Maintain drainage
Reduce debris infiltration into joints or cracks
Slow aging effects of bituminous pavements
Minimize dynamic loads
Based on all of the types of preventive maintenance techniques that have been presented in this module, what types of things does preventive maintenance specifically do to “preserve the investment?”
Many of the preventive maintenance activities are applied to “keep water out.” Reducing the potential for water infiltration and maintaining well performing drainage will help protect the underlying layers from being softened or washed away. Reducing water infiltration also reduces that effects of freezing and thawing in colder climates.
The same preventive maintenance techniques that keep water out, also keep incompressible debris from entering joints or cracks. Keeping incompressibles out of joints and cracks greatly reduces the potential for HMA and PCC crack deterioration, PCC joint spalling, and blow-ups in PCC pavements.
Surface treatments can be used to slow asphalt aging/hardening on HMA pavements.
The rougher the pavement surface, the higher the impact of dynamic vehicle loadings.

38. How is PM used to maintain an acceptable LOS for the pavement surface?
Maintain good rideability
Maintain good surface friction
Minimize additional dangerous surface characteristics
Edge drop-off
Rutting (hydroplaning)
Based on all of the types of preventive maintenance techniques that have been presented in this module, what types of things does preventive maintenance specifically do to “maintain an acceptable level of service for the pavement surface?”
Many of the preventive maintenance activities are applied to “maintain good rideability.” Pavement smoothness is probably the pavement characteristic most noticed by the traveling public.
Other preventive maintenance activities are applied specifically to improve the pavement surface friction. Maintaining good surface friction improves roadway safety (mainly by reducing hydroplaning potential, and therefore, wet-weather accidents).

39. Specific Results of Preventive Maintenance Treatment Applications
Prevent or slow some distresses from occurring
Correct some (mostly minor) surface deterioration
Specifically, PM treatments have two different uses:
Prevent or slow many distresses from ever occurring (blow-ups, sealed joints and cracks prevent softening of subgrade due to water infiltration).
Correct some surface distress when applied (surface friction restoration, microsurfacing to fill ruts). Most surface distress addressed with PM is minor. Make the point that PM does not address all types and severities of surface distress.

40. Pavement Problems Prevented or Slowed with PM Treatments
HMA Problems
PCC Problems
Loss of fines (pumping)
Crack deterioration
Block cracking
Edge cracking
Potholes
Weathering/raveling
Roughness
Corner breaks
Blow-ups
Joint spalling
Joint faulting
What other types of pavement problems can be prevented or slowed with PM treatments?

41. Common Pavement Problems Corrected with PM Treatments
HMA Problems
PCC Problems
Non subgrade softening rutting
Raveling
Bleeding/flushing
Surface friction loss
Roughness
Joint seal damage
Map cracking and scaling
What other types of pavement problems can be corrected with PM treatments?
Make the point that rutting is correctable under preventive maintenance only if 1) it is relatively minor, and 2) its development is not due to subgrade softening.
Note: we are not talking about structural problems in this table.

42. Importance of Distress when Selecting PM Candidates and Appropriate PM Treatments

43. Significance of Distress
Feasibility of PM treatments
Selecting “good candidates” for PM
Selecting appropriate PM treatments
What you don’t see may be as important as what you do see!
Pavement condition data is not used in the traditional reactive methods used for determining pavement rehabilitation.
What makes distress such an important consideration in a preventive maintenance program?
Like the selection of other types of maintenance and rehabilitation, distress offers a basis for the defining the feasibility of various candidate preventive maintenance treatments.
If an agency is pursuing a preventive maintenance program, observations of distress will provide a sound basis for identifying the pavements which are the best candidates for preventive maintenance.
When it comes to identifying appropriate preventive maintenance treatments for a given project or identifying candidate projects for pavement maintenance, pavement distress is an essential consideration.
Furthermore, limitations on the applications of preventive maintenance make what you don’t see as important as what you do.
A survey of current distress is the best estimate of where your pavement is in the typical expected pavement deterioration process.
We are trying to get to the point where we have “objective” criteria that tells you when it is 1) too late or 2) too early for preventive maintenance. The next cutting edge research is to detect these indicators prior to seeing distress (i.e., NDT methods). What do you measure to obtain such answers? We currently don’t have a good handle on this question. However, we DO know “pavement distress progression,” we DO know “pavement distress,” and we DO know when it is too late to apply PM.

44. When should preventive maintenance be applied?
Good
Defer
Action
Reconstruction
Pavement
Condition
(Functional or
Structural)
Rehabilitation
Going back to the earlier slide used to illustrate the concept of pavement deterioration and performance, it is easy to super-impose the regions of the deterioration curve where the different categories of maintenance, rehabilitation, and reconstruction would be applicable. As is indicated, preventive maintenance is an activity that is exercised early in the pavement life when the overall condition of the pavement is at relatively high level. Given this, it should be clear that the distress surveys required for a preventive maintenance program must take place early in the pavement life (say, 3 to 6 years for flexible pavements and 4 to 8 years for rigid pavements).
It is important to “learn from your pavements” as these ranges will differ for each group of pavements with similar characteristics (pavement type, materials, environment, construction quality, traffic, etc.) In addition, to determining the appropriate timing of first preventive maintenance application, one also must determine the most appropriate frequency for additional applications.
Point out that we currently don’t know when the window for preventive maintenance ends. It is most likely different for every combination of pavement type, climatic conditions, materials, subgrade support, etc.
Poor
Time (Years)

45. When should preventive maintenance be applied?
Good
Pavement
Condition
(Functional or
Structural)
Make point that if you start PM when pavement is in good condition, you can continue to maintain a high LOS with repeated applications of relatively inexpensive PM treatments.
Poor
Time (Years)

46. When is it too late for preventive maintenance?
HMA Problems
PCC Problems
Potholes
Severely deteriorated cracks
Delamination
Unstable rutting
Others?
Blow-ups
Corner breaks
See if the class can identify that signs of structural deterioration are indicators that preventive maintenance is not appropriate.

47. Maximum Allowable Distresses HMA Pavements
Extent of Problem
Distress Type
Minor
Major
Fatigue Cracking
Linear & Block Cracking
“Stable” Rutting
Raveling
Flushing/Bleeding
Roughness
Friction Loss
Moisture Damage
Shoving
This bar chart shows general guidelines for the maximum state of distress (in terms of extent and severity) that is allowable in a flexible pavement if it is to be considered a candidate for preventive maintenance. The term “extent” is meant to incorporate both severity and amount. More specific guidelines will be presented (by treatment) in session 4.

48. Maximum Allowable Distresses PCC Pavements
Extent of Problem
Distress Type
Minor
Major
Linear Cracking
Corner Breaks
Trans. Joint Faulting
Joint Spalling
D-Cracking
Pumping
Roughness
Friction Loss
Surface Distress
This bar chart shows general guidelines for the the maximum state of distress (in terms of extent and severity) that is allowable in a PCC pavement if it is to be considered a candidate for preventive maintenance. The term “extent” is meant to incorporate both severity and amount. More specific guidelines will be presented (by treatment) in session 4.
Note: surface distress involves all mix problems that cause surface distress (i.e., map cracking, scaling, etc.)

49. Review of Learning Objectives
Define pavement condition and describe typical pavement survey types
Identify common HMA and PCC distress types

50. Review of Learning Objectives (continued)
Describe the typical progression of deterioration for HMA and PCC pavements
Describe the effect of preventive maintenance on the typical progression of pavement deterioration

51. Review of Learning Objectives (continued)
Describe the importance of pavement condition survey data in developing preventive maintenance guidelines