Reference Manual
Module 2-2. Pavement Distress and Drainage Surveys
MODULE 2-2. PAVEMENT DISTRESS AND DRAINAGE SURVEYS
1.
INSTRUCTIONAL OBJECTIVES
This module describes recommended procedures for conducting pavement distress and drainage surveys
on existing HMA pavements. Upon completion of this module, the participants should be able to
accomplish the following:
1. Describe the reasons for conducting pavement distress surveys and drainage surveys.
2. List the three factors required to characterize pavement distress.
3. Identify the various types of HMA distress and their probable causes.
4. Describe the key components of a manual pavement distress survey and a drainage survey.
5. Describe ways of analyzing and presenting distress survey results.
2.
INTRODUCTION
Pavement distress surveys are the first step in the overall pavement evaluation process. These surveys
record visible distresses on the surface of the pavement, and are performed for the following reasons:

Document pavement condition.

Identify types of distress.

Group areas of pavement exhibiting similar performance.

Gain insight into causes of deterioration (e.g., structural vs. functional).

Identify additional testing needs.

Identify potential rehabilitation treatments.

Identify repair areas and repair quantities.
By identifying the types of distress, a great deal of information can be inferred regarding the underlying
causes of deterioration. Ultimately, this information can help in the selection of appropriate rehabilitation
measures.
As part of a pavement distress survey, it is also important to assess the overall drainage conditions of the
existing pavement. This is because poor drainage conditions have long been recognized as a major cause
of distress in pavement structures, and unless moisture-related problems are identified and corrected
where possible, the effectiveness of any rehabilitation treatment will be reduced. The purposes of
conducting a drainage survey are to:

Identify the presence of moisture-related distresses.

Document the prevailing drainage conditions of the pavement (e.g., cross slopes, cut/fill areas,
depth and condition of ditches).

Assess the condition and effectiveness of edge drains (if present).
The detection of possible drainage problems as evidenced from a drainage survey may suggest the need
for an in-depth analysis of the drainability of the pavement structure. A computer program has recently
been developed by FHWA that can assist in such an analysis (Wyatt, Barker, and Hall 1998).
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Module 2-2. Pavement Distress and Drainage Surveys
3.
Reference Manual
DEFINITIONS
Types of Distress Surveys
Distress surveys can be conducted at either the project level or the network level. Project-level surveys
are more detailed surveys that are performed on specific projects targeted for rehabilitation; the goal is the
identification of the specific pavement deficiencies and the selection of the most appropriate rehabilitation
strategy. Network-level surveys are typically less detailed surveys that are conducted on selected
pavement sections within the pavement network; the goal is the identification of rehabilitation priorities
and the allocation of funding.
Pavement Distress
Pavement distress is any visible defect or form of deterioration on the surface of a pavement, and is the
most basic measure of the performance of an existing pavement. In order to fully describe pavement
distress, the following three factors must be considered:

Type—The type of distress is determined primarily by similar mechanisms of occurrence and
appearance.

Severity—The severity of distress represents the criticality of the distress in terms of progression;
more severe distresses will require more extreme rehabilitation measures.

Amount—The quantity of each type and severity level must be measured and expressed in
convenient terms.
Any method of distress measurement that ignores one of these three factors will not provide adequate
information for design of a rehabilitation project.
Distress Identification Manuals
In recent years, significant progress has been made in the standardization of distress identification in the
form of distress identification manuals. Several have been developed for different applications including
highways (Smith, Darter, and Herrin 1979; SHRP 1993), streets (Shahin and Walther 1990), and airports
(FAA 1982).
One manual that has seen widespread use is the Distress Identification Manual for the Long-Term
Pavement Performance Project (SHRP 1993), which was developed under the Strategic Highway
Research Program (SHRP) to provide a uniform basis for the identification and measurement of pavement
distresses for the SHRP Long-Term Pavement Performance Program (LTPP) research study. The manual
includes distresses for the following pavement types:

HMA pavements (including HMA overlays).

Plain and reinforced jointed concrete pavements (including concrete overlays).

Continuously reinforced concrete pavements.
The manual describes the appearance of each distress type, depicts the associated severity levels (where
defined), and describes the standard units in which the distress is measured. Figures and photographs of
the distress type at various levels of severity are also provided to aid the surveyor in the distress
identification process. Table 2-2.1 summarizes the distresses defined for HMA pavements in the SHRP
manual, and also notes whether the distresses are primarily traffic related or climate/materials related.
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Module 2-2. Pavement Distress and Drainage Surveys
Table 2-2.1. Summary of HMA distress types defined in SHRP Distress Identification manual.
Distress
Type
Unit of
Measure
Severity
Levels?
Primarily
Traffic/Load
Fatigue Cracking
Block Cracking
Edge Cracking
Longitudinal Cracking (wheelpath)
Longitudinal Cracking (non-wheelpath)
Transverse Reflection Cracking
Longitudinal Reflection Cracking
Transverse Cracking
Sq. Meters
Sq. Meters
Meters
Meters
Meters
Number, Meters
Meters
Number, Meters
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
X
Number, Sq. Meters
Number, Sq. Meters
Yes
Yes
X
X
Millimeters
Number, Sq. Meters
No
No
X
X
Square Meters
Square Meters
Square Meters
Yes
No
Yes
Millimeters
Number, Meters
No
No
Primarily
Climate/Materials
Cracking
X
X
X
X
X
X
X
Patching and Potholes
Patch/Patch Deterioration
Potholes
Surface Deformation
Rutting
Shoving
Surface Defects
Bleeding
Polished Aggregate
Raveling
X
X
X
Miscellaneous Distresses
Lane-to-Shoulder Dropoff
Water Bleeding and Pumping
X
X
AASHTO Provisional Standards for Measuring Pavement Condition
Many agencies have developed their own distress identification manuals and definitions for use in their
pavement management systems (Gramling 1994). Furthermore, in an effort to provide some consistency
in the way that network-level distress data are collected, the FHWA, in conjunction with AASHTO, has
supported the development of the following four protocols (Grogg 2000):




PP37-00, Standard Practice for Determining Roughness of Pavements.
PP38-00, Standard Practice for Determining Rut Depth in Asphalt Pavements.
PP39-00, Standard Practice for Estimating Faulting of Concrete Pavement.
Standard Practice for Measuring Cracking in HMA Pavements.
The first three protocols have been balloted and passed by AASHTO to become provisional standards; the
fourth protocol has not passed balloting by AASHTO and is still undergoing revision (Grogg 2000).
4.
CONDUCTING PAVEMENT DISTRESS SURVEYS
This section describes how pavement distress surveys are typically performed. The focus of the
information is on the conduct of manual distress surveys (i.e., “walking” surveys in which data are
recorded on survey forms), as these are generally most appropriate for project-level pavement
evaluations. However, some information is also presented on automated distress surveys.
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Manual Distress Surveys
A manual distress survey is a “walking” survey of the pavement in which the entire limits of the project
are evaluated and all distresses are measured, recorded, and mapped (Gramling 1994). Manual distress
surveys have been performed for many years and serve as a cornerstone in the development of
rehabilitation alternatives. With adequate field training of the survey crew, these surveys provide reliable
and consistent results in characterizing the condition of the pavement. Equipment needed for a manual
distress survey is readily available and should include (Van Dam et al. 2001):

Hand odometer (measuring wheel) or tape measure (at least 30 m [100 ft]) for measuring
distances.

Stringline or straightedge between 1 and 2 m (0.3 and 0.6 ft) for measuring rut depth and/or
dropoff.

Small scale or ruler for fine measurements.

Marking paint or lumber crayon to mark distresses or record stationing along project.

Mid- to full-sized vehicle.

Faultmeter or other means for measuring crack faulting or lane-shoulder dropoff.

Data collection forms or sheets.

Clipboard and pencils.

SHRP Distress Identification Manual or agency-approved equivalent.

Camera or videotape for capturing representative distresses and conditions.

Hard hats and safety vests.

Traffic control provisions.
Again, the purpose of a conducting a manual distress survey is to determine the condition of a specific
project so that appropriate rehabilitation alternatives can be identified. Elements of a manual distress
survey are described in the following sections.
Presurvey Activities
Prior to any fieldwork, a preliminary records review should be conducted on the project. This should
include information needed to assist in the conduct of the field surveys, such as general location
information, general structural design information (pavement type, layer thicknesses, subgrade type, and
so on), traffic information, and data from any previous distress surveys. Ultimately, complete historical
information on the project must be obtained.
Arrangements for the provision of traffic control should also be made prior to any fieldwork. Although
some of the work can be performed from the shoulder, the pavement evaluator must be allowed on the
pavement with the freedom to closely inspect the entire pavement. In addition, any sampling and testing
activities that will be conducted will require complete access to the pavement. All traffic control
arrangements should be scheduled as far in advance as possible and should adhere to the guidelines
provided in the Manual on Uniform Traffic Control Devices (MUTCD) or the agency’s governing
requirements (FHWA 2000).
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Module 2-2. Pavement Distress and Drainage Surveys
Windshield Survey
As a first step in the pavement distress survey, a “windshield survey” should be conducted in which the
entire project is driven in each lane in both directions at posted speed limits to get an overall “feel” or
impression for how the pavement is performing. This is also the easiest way to get a measure of the
pavement rideability. During these passes, any swells, depressions, or other sources of discomfort should
be recorded and any locations of medium- to high-severity swells or depressions should be noted by
milepost. Also, any apparent discrepancies in overall pavement condition or performance over the length
of the project should be noted.
Detailed Distress Survey
A manual distress survey uses a two-person crew that walks along the shoulder of the entire project. One
member of the crew is the recorder, who records and maps all of the distresses that appear on the
pavement surface. The other member of the crew is the rater, who calls out the various distress types and
obtains pertinent measurements associated with each distress. However, both members of the survey
crew should be thoroughly familiar with the distress identification manual being used on the project. In
most cases, both travel lanes and shoulders should be included in the survey. As previously described, if
the project is on a busy roadway, traffic control should be provided for the safety of the survey crew.
The data collection forms that are used to record the distresses can be easily developed to fit an agency’s
objectives for distress surveys. These should be developed with the intended use of the data in mind in
order to minimize future work. In addition, it is generally recommended that mapping of the project be
conducted in order to help identify critical repair areas, although in some cases this may not be necessary.
The field survey form used in the SHRP Distress Identification Manual is shown in figure 2-2.1 (SHRP
1993); other example field survey forms can be found in references by Hicks and Mahoney (1981) and by
Goulias, Castedo, and Hudson (1990).
Some agencies have also used portable, hand-held computers to aid in the collection of distress data.
Users can input distress quantities and amounts directly into the computer, which can then be downloaded
for further evaluation. These can be convenient for reducing paperwork and are also effective in reducing
transcription errors; some models also allow mapping of actual distresses. Field surveys using computers
do proceed a little slower than surveys with data collection forms, but the time is made up in the
processing of the data.
At the conclusion of the distress survey, it is recommended that a complete photo or video summary of
the project be performed (Van Dam et al. 2001). The purpose of this photo summary is to fully and
completely document the condition of the pavement, as well as to record the prevailing foundation and
drainage characteristics of the roadway. Either a photo log or video log may be conducted, although the
best documentation may be captured using both technologies: the photo log for conveying pavement
condition in reports and presentations, and the video log for providing a more complete record of the
overall pavement condition (Van Dam et al. 2001).
Automated Distress Survey Equipment
In recent years, tremendous advances have been made in the development of automated equipment that
can be used to collect, store, and process pavement condition data. These devices take photographic
images or other visual images of the pavement surface, which decreases the data collection time and
provides a permanent record of the pavement condition. Although typically more appropriate for
network-level surveys, there may be some instances where they are appropriate for project-level surveys,
such as extremely long projects or projects in heavily congested areas. Noted advantages of automated
distress survey equipment include (Sime and Larsen 1990):
HMA Pavement Evaluation and Rehabilitation
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2-2.6
0m
1m
2m
3m
4m
5m
0m
1m
2m
3m
4m
5m
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15 m
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30 m
Figure 2-2.1. SHRP field data collection form (SHRP 1993).
Comments: ________________________________________________________________________
15 m
Comments: ________________________________________________________________________
0m
State Assigned ID ___________
____
State Code
___________
SHRP Section ID
Module 2-2. Pavement Distress and Drainage Surveys
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Module 2-2. Pavement Distress and Drainage Surveys

Measurement of distresses at highway speeds.

More consistent measurements.

Increased safety.

No disruption to traffic flow.

Predictable productivity.

Highly objective output.

Increase in sample size.

Cost savings over manual, long term.

Less traffic control and less man hours.
In addition, some automated devices often have the capability to measure additional performance
indicators, such as roughness, surface texture, longitudinal profile, rutting. Furthermore, some equipment
also can inventory other infrastructure elements, such as signs and markings.
Many different types of equipment are available for automated collection of distress data. It should be
noted, however, that the various types of equipment differ in measurement capabilities and sensitivity,
data processing and storage procedures, format of data outputs, and cost. Thus, any agency considering
the purchase or lease of automated data collection equipment is strongly encouraged to research the
capabilities of each type to ensure that they match those characteristics desired by the agency.
Another issue in the use of automated distress data collection is the way that the resulting images are
interpreted. In its simplest form, they can be interpreted manually be an individual viewing the images at
a computer work station. At the other extreme is the movement towards the automated analysis of
images, but this has been found to be very complex because of the varying patterns, colors, and textures
of the pavement.
Additional information regarding the capabilities of some of the automated data collection equipment can
be found in references by Epps and Monismith (1986), Cable and Marks (1990), and Smith, Freeman, and
Pendelton (1998).
Some agencies also conduct network-level surveys with pavement evaluators sitting in a van, recording
distresses while the van driver advances the vehicle slowly along the shoulder. Such surveys are adequate
for obtaining an overall indication of the typical condition of a pavement section, but typically do not
provide project-level inputs required for rehabilitation.
5.
PAVEMENT DRAINAGE SURVEYS AND EVALUATION
Because the development of so many pavement distresses is related to the presence of excess moisture in
the pavement structure, it is helpful during the distress survey to also conduct a drainage survey. In a
drainage survey, visual signs of poor drainage are noted and can be coupled with information from
materials sampling testing and nondestructive deflection testing (NDT) to provide some insight into the
overall drainability of the pavement structure. Unless moisture-related problems are recognized and
corrected where possible, the effectiveness of any rehabilitation activity will be reduced.
This section describes the drainage survey activities that should be conducted as part of the pavement
distress survey. It also briefly describes how the drainability of an existing pavement structure can be
evaluated, although the details of that evaluation are beyond the scope of this manual and are therefore
not presented here.
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Drainage Survey
A drainage survey is an assessment of the drainage characteristics of the pavement system. The purposes
of conducting a drainage survey are to identify the presence of moisture-related distresses, document the
prevailing drainage conditions of the pavement, and to assess the condition and effectiveness of edge
drains (if present). The overall goal is to determine if excess moisture is compromising the performance
of the pavement so that suitable rehabilitation treatments can be identified.
The drainage survey is conducted at the same time as the manual distress survey. Particular attention
should be given to the severity and extent of those distresses that are known to be moisture-related to help
assess the degree to which excess moisture may be contributing to the pavement deterioration. These
distressed areas should be marked and noted on strip maps. In addition, the following drainage-related
items should be noted as part of the drainage survey:

Topography of the project. The overall topography and the approximate cut/fill depth should be
noted along the length of the project to help determine if more distresses occur in certain cut or
fill areas.

Transverse slopes of the shoulder and pavement. These should be evaluated to ensure that they
are not ponding water or preventing the effective runoff of moisture from the surface. Recent
research on surface drainage has suggested a minimum 2 percent slope for mainline pavements
and a 3 percent slope for shoulders to help reduce hydroplaning (Anderson et al. 1998). Some
cross slope corrections may be possible during rehabilitation if an inadequate cross slope exists.

Condition of the ditches. The condition of the ditches (and the embankment material adjacent to
the shoulder) should be noted along the length of the project to see if they are clear of standing
water, debris, or vegetation that might otherwise impede the flow of water. The presence of
cattails or willows growing in the ditch is a sign of excess moisture.

Geometrics of the ditches. The depth, width, and slope of the ditches should be noted along the
length of the project to ensure that they facilitate the storage and movement of water. It is
generally recommended that ditches be 1.2 m (4 ft) below the surface of the pavement, be at least
1 m (3 ft) wide, and have a minimum slope of 1 percent.

Condition of drainage outlets (if present). These should be assessed over the entire length of the
project to ensure that they are clear of debris and set at the proper elevation above the ditchline.
The overall condition of the outlets and headwall (if present) should also be assessed, and the
presence or absence of outlet markers noted.

Condition of drainage inlets (if present). Many urban projects incorporate drainage inlets to
remove surface water, and these should also be inspected over the length of the project. They
should be free of debris, with adequate cross slopes on the pavement surface.
If edgedrains are present, their effectiveness should be evaluated by observing their outflow either after a
rainfall or after water is released from a water truck over pavement discontinuities. The flow from each
outlet should be examined and any outlets that are flowing at a much lower rate than the others should be
noted on a strip map.
Another way of assessing the effectiveness of edgedrains is through the use of video inspections
(Christopher 2000). This inspection uses a high-resolution, high-sensitivity color video camera attached
to a pushrod cable approximately 15 mm (0.6 in) in diameter and 150 m (500 ft) long (Daleiden 1998).
The device is inserted into the drainage system at the outlets, and as the camera is pushed along, a VCR
records the inspection in progress and simultaneously notes the distances that the camera has advanced
(Daleiden 1998). In this way, any blockages, rodents’ nests, or areas of crushed pipes can be located.
Several states have now adopted video edgedrain inspection as part of new drainage construction.
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Module 2-2. Pavement Distress and Drainage Surveys
All of the information collected from the drainage surveys should be marked and noted on strip maps, and
then examined together to obtain a visual picture of what moisture is doing to the pavement, where any
moisture damage is occurring, and what factors are present that allow this moisture damage to occur.
Drainage Evaluation
The analysis of the drainability of an existing pavement system is a complex undertaking, and beyond the
scope of this course. Given below is a brief description of the process, with more detailed information
provided in references by Moulton (1980), FHWA (1992), and ERES (1999).
The following basic information is required for conducting a detailed drainage evaluation of an existing
pavement (Moulton 1980):

Properties of the subgrade and paving materials (e.g., gradation, permeability, porosity).

Geometrics of the roadway and pavement structure (e.g., transverse and longitudinal slopes, cross
section information).

Climatic data for the geographic area (e.g., precipitation, depth of frost penetration).
Most of the pavement information can be obtained from plans, specifications, and other historical data,
but material sampling is often recommended to confirm layer thicknesses and properties. Climatic data
can be obtained from county soil maps or from the National Climatic Data Center at www.ncdc.noaa.gov.
Once this information has been collected, there are a series of computations performed to estimate the
time it takes to drain water from the pavement structure to a prescribed level of saturation. Generally, a
saturation level of 85 percent is considered critical for granular base layers in terms of the magnitude of
deflection. Thus, it is expected that the time required to reach an 85 percent saturation level will directly
relate to the amount of damage done by repeated traffic loading. Generally speaking, a drainage time of 5
hours to a saturation level of 85 percent is considered acceptable, a drainage time between 5 and 10 hours
to an 85 percent saturation level represents a marginal condition, and a drainage time greater than 10
hours to an 85 percent saturation level is unacceptable (Smith et al. 1990). These recommendations are
for high-volume interstate pavements carrying significant truck traffic; lower-volume roads can tolerate
longer drainage times without sustaining excessive damage.
The computations referred to above can be done manually using various charts, graphs, and tables found
in reports by Moulton (1980) and the FHWA (1992). However, the use of these manual procedures tends
to be rather slow and laborious. As mentioned previously, a computer program called DRIP is now
available that greatly facilitates the conduct of detailed drainage designs and analysis (Wyatt, Barker, and
Hall 1998). The program is applicable to both new and rehabilitated pavements, as it not only determines
pavement drainage times using the given material property, geometric, and climatic data, but also
performs permeable base, separator layer, and edge drain designs based on the drainage requirements of
the pavement system (Wyatt, Barker, and Hall 1998).
6.
EVALUATION OF SURVEY RESULTS
Upon completion of the distress and drainage surveys, the critical distresses and drainage conditions
should be summarized for the project. One useful way of summarizing the results is through a strip chart
that shows the occurrence of various distresses over the length of the project. Primary distresses such as
rutting and fatigue cracking are often plotted, but other important performance parameters such as
roughness and surface friction (see module 2-4) can also be included. And when other important
pavement evaluation information, such as deflections, soil types, and traffic volumes, are added to the
strip chart, a more complete picture of the overall pavement condition is obtained and additional insight
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2-2.9
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into possible causes of distress is gained. In addition, a strip chart can also assist in identifying
particularly troublesome areas for more detailed materials and pavement testing.
An example strip chart is shown in figure 2-2.2. This figure plots the severity of fatigue cracking (FC)
along the length of the project. Three different fatigue cracking “conditions” are noted over the length of
the project, and it is observed that the worst condition (condition 1) occurs in an area with high traffic
levels and a silty clay subgrade. The “best” performance is observed in an area with low traffic levels and
a granular subgrade. Other factors, such as cut and fill areas, depth of ditches, and condition of drainage
outlets (if present) could also be added to the strip chart to provide greater insight into the performance of
this pavement.
Silty Clay
Granular
High Traffic
Silty Clay
Low Traffic
Condition 1 Condition 2 Condition 3
FC
(%)
Severity
Low
Medium
High
Distance Along Project
Figure 2-2.2. Example strip chart.
The strip chart is one way of using the data from the distress and drainage surveys to gain greater insight
into why pavements are performing the way they are. Other uses for the information obtained from the
distress and drainage surveys are listed below:
1. Distresses and other deficiencies requiring repair can be identified and corresponding repair
quantities can be estimated. If there is a delay between the conduct of the field survey and the
rehabilitation project, it is generally recommended that a follow-up survey be conducted just prior
to advertisement to ensure that contract quantities are still valid.
2. An overall examination of the data along the project will reveal if there are significantly different
areas of pavement condition along the project. For example, a change in subgrade, traffic, or
materials may result in a significant change in pavement performance (and hence the occurrence
of distress). In addition, the inner lanes of multilane facilities may exhibit significantly less
distress or lower severity levels of distress than the outer lane. By recognizing these trends,
rehabilitation designs can be varied along the project and/or across lanes to reduce costs.
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Module 2-2. Pavement Distress and Drainage Surveys
3. The condition survey data provides permanent documentation of the condition of the existing
pavement. This lends itself to several uses, including the monitoring of the pavement
performance over time, the comparison of pavement performance before and after rehabilitation,
and also the development of performance prediction models and curves.
4. The data provide an excellent source of information with which to plan the structural and
materials testing of the pavement (see modules 2-3 and 2-5).
5. The data provides valuable insight into the mechanisms of pavement deterioration. As a first
step, the deficiency can be identified as being either primarily load-associated or primarily
climate/materials-associated (see table 2-2.1 presented earlier). If the distress is primarily loadassociated, rehabilitation work should include a structural improvement. If climatic conditions or
paving materials are contributing to the deterioration, appropriate measures should be identified
to address those deficiencies or to lessen their impact or effect on pavement performance. If
serious climatic- or materials-related problems exist, the best solution may be complete
reconstruction.
6. If time-series condition data are available (that is, performance data collected on a pavement at
different points in time), then information can be obtained regarding the time that the various
deficiencies began to appear and their relative rates of progression. Such information can be
extremely valuable in identifying causes of condition deficiencies and in programming
appropriate rehabilitation actions (e.g., determining if a certain pavement can wait 3 years for an
overlay or whether it then will be too deteriorated).
7.
SUMMARY
Information on performing project distress and drainage surveys is presented in this module. These are
typically the first part of the overall pavement evaluation process and are needed to fully characterize the
distress and drainage characteristics of the pavement.
Pavement distress must be defined in terms of type, severity, and amount in order to fully characterize the
condition of the existing pavement. By knowing the type of distress, insight as to whether the distress is
primarily load-related or primarily materials/climate-related can be gained, which in turn will assist in the
selection of the appropriate rehabilitation treatment. Certain distresses are directly related to the presence
of moisture in the pavement system, and an examination of the distress will indicate the extent to which
moisture-related problems have developed in the pavement.
Pavement distress surveys may be conducted either manually or by automated data collection equipment,
although the latter is typically reserved for network-level evaluations. The results of the distress survey
can provide information on the following:

Estimates of needed repair locations and quantities.

Significant changes in condition along the project.

Documentation of the condition of the existing pavement.

Additional testing needs.

Causes and mechanisms of pavement deterioration.
Drainage surveys are performed as part of a pavement distress survey in order to assess the overall
drainage conditions of the existing pavement. This is because poor drainage conditions have long been
recognized as a major cause of distress in pavement structures, and unless moisture-related problems are
identified and corrected where possible, the effectiveness of any rehabilitation treatment will be reduced.
The purposes of conducting a drainage survey are to:
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
Identify the presence of moisture-related distresses.

Document the prevailing drainage conditions of the pavement (e.g., cross slopes, cut/fill areas,
depth and condition of ditches).

Assess the condition and effectiveness of edge drains (if present).
Through a drainage survey and evaluation, it is possible to identify where excessive moisture exists and
what materials are affected, both of which will greatly assist in the selection of an appropriate
rehabilitation treatment.
The results from the distress and drainage surveys can be used in a number of ways in order to assess the
overall condition of the existing pavement. One very effective way of presenting the results is through
strip charts, which show the condition of the pavement over the length of the project. These strip charts
can be overlaid with additional pavement information (such as subgrade, traffic, and drainage conditions)
in order to provide greater insight into pavement behavior. By viewing the strip chart, it is also possible
to identify subprojects within a project that may require less extensive rehabilitation measures, which
could result in significant cost savings.
8.
REFERENCES
Anderson, D. A., R. S. Huebner, J. R. Reed, J. C. Warner, and J. J. Henry. 1998. Improved Surface
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NOTES
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