Structural Design of Highway
Flexible Pavement Design
Flexible Pavement Design
Highway and Transportation Engineering
Al-Mustansiriyah University
2019-2020
Yoder; E. J. and M. W. Witczak, “Principles of Pavement Design”, A Wiley-
Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
Structural Design of Highway
Structural Design of Highway
Dr. Rana Amir Yousif & Dr. Abeer K. Jameel
Yoder; E. J. and M. W. Witczak, “Principles of Pavement Design”, A
Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
References
References
Nicholas J. Garber and Lester A. Hoel.”Traffic and Highway Engineering”,
Fourth Edition.
Yoder; E. J. and M. W. Witczak, “Principles of Pavement Design”, A Wiley-
Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
Yaug H. Huang, “Pavement Analysis and Design”, Prentic Hall Inc., U.S.A.,
1993.
“AASHTO Guide for Design of Pavement Structures 1993”, AASHTO,
American Association of State Highway and Transportation Officials, U.S.A.,
1993.
Oglesby Clarkson H., “Highway Engineering”, John Wiley & Sons Inc.,
U.S.A., 1975.
Yoder; E. J. and M. W. Witczak, “Principles of Pavement Design”, A
Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
AASHTO METHOD
AASHTO METHOD
The design procedure recommended by the American Association of State Highway
and Transportation Officials (AASHTO) is based on the results of the extensive
AASHO Road Test conducted in Ottawa, Illinois, in the late 1950s and early 1960s .
The AASHO Committee on Design first published an interim design guide in 1961 . It
was revised in 1972 and 1981 .
In 1984-85, the Subcommittee on Pavement Design and a team of consultants revised
and expanded the guide under NCHRP Project 20-7/24 ; they issued the guide in 1986 .
The guide was revised in 1993 with practically no change in the design method
presented in this section .
Yoder; E. J. and M. W. Witczak, “Principles of Pavement Design”, A
Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
11.3 AASHTO METHOD
11.3 AASHTO METHOD
11 .3.1 Design Variables
11 .3.1 Design Variables
Several general design variables related to both flexible and rigid pavements are presented
in this section .
T
T
ime Constraints
ime Constraints
To achieve the best use of available funds, the AASHTO design guide
encourages the use of a longer analysis period for high-volume facilities, including at least
one rehabilitation period . Thus, the analysis period should be equal to or greater than the
performance period, as described below.
P
P
erformance Period
erformance Period
The performance period refers to the time that an initial
pavement structure will last before it needs rehabilitation or the performance time
between rehabilitation operations . It is equivalent to the time elapsed as a new,
reconstructed, or rehabilitated structure deteriorates from its initial serviceability to its
terminal serviceability.
Yoder; E. J. and M. W. Witczak, “Principles of Pavement Design”, A
Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
11.3 AASHTO METHOD
11.3 AASHTO METHOD
11 .3.1 Design Variables
11 .3.1 Design Variables
N
N
ote
ote
The selection of performance period can be affected by such factors:
The selection of performance period can be affected by such factors:
T
T
he functional classification of the pavement.
T
T
he type and level of maintenance applied.
T
T
he funds available for initial construction.
L
L
ife cycle costs.
a
nd other engineering considerations.
The designer must select the performance period within the
The designer must select the performance period within the
minimum and maximum allowable bounds that are
minimum and maximum allowable bounds that are
established by agency experience and policy.
established by agency experience and policy.
Yoder; E. J. and M. W. Witczak, “Principles of Pavement Design”, A
Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
11.3 AASHTO METHOD
11.3 AASHTO METHOD
11 .3.1 Design Variables
11 .3.1 Design Variables
A
A
nalysis Period
nalysis Period
The analysis period is the
period of time that any design strategy must
cover . It may be identical to the selected
performance period .However, realistic
performance limitations may necessitate the
consideration of staged construction or
planned rehabilitation for the desired analysis
period .
Table 11.13
Table 11.13
contains general guidelines for the
length of the analysis period .
Yoder; E. J. and M. W. Witczak, “Principles of Pavement Design”, A
Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
11.3 AASHTO METHOD
11.3 AASHTO METHOD
11 .3.1 Design Variables
11 .3.1 Design Variables
T
raffic:
The design procedures are based on cumulative expected 18-kip (80-kN)
equivalent single-axle load (ESAL) .
If a pavement is designed for the analysis period without any
If a pavement is designed for the analysis period without any
rehabilitation or resurfacing, all that is required is the total ESAL
rehabilitation or resurfacing, all that is required is the total ESAL
over the analysis period . However, if stage construction is
over the analysis period . However, if stage construction is
considered and rehabilitation or resurfacing is anticipated, a graph or
considered and rehabilitation or resurfacing is anticipated, a graph or
equation of cumulative ESAL versus time is needed so that the
equation of cumulative ESAL versus time is needed so that the
ESAL traffic during any given stages can be obtained .
ESAL traffic during any given stages can be obtained .
N
N
ote
ote
Yoder; E. J. and M. W. Witczak, “Principles of Pavement Design”, A
Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
11.3 AASHTO METHOD
11.3 AASHTO METHOD
11 .3.1 Design Variables
11 .3.1 Design Variables
R
eliability:
The design procedures are based on cumulative expected 18-kip (80-kN)
equivalent single-axle load (ESAL) .
Yoder; E. J. and M. W. Witczak, “Principles of Pavement Design”, A
Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
11.3 AASHTO METHOD
11.3 AASHTO METHOD
11 .3.1 Design Variables
11 .3.1 Design Variables
Application of the reliability concept requires the selection of a standard deviation that is representative of local
conditions . It is suggested that standard deviations of 0 .49 be used for flexible pavements and 0 .39 for rigid
pavements. These correspond to variances of 0 .2401 and 0 .1521, which are nearly the same as those shown in
Table 10.12 .
.
When stage construction is considered, the reliability of each stage must be
compounded to achieve the overall reliability ; that is,
(11.28)
in which
in which
n is the number of stages being considered
n is the number of stages being considered
.
.
For example, if two stages are contemplated and the
desired level of overall reliability is 95%, the reliability of each stage must be (0 .95) ^1/2 , or 97.5% .
Yoder; E. J. and M. W. Witczak, “Principles of Pavement Design”, A
Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
11.3 AASHTO METHOD
11.3 AASHTO METHOD
11 .3.1 Design Variables
11 .3.1 Design Variables
E
nvironmental Effects :
The AASHO design equations were based on the results of
The AASHO design equations were based on the results of
traffic tests over a two-year period . The long-term effects of temperature and moisture
traffic tests over a two-year period . The long-term effects of temperature and moisture
on the reduction of serviceability were not included . If problems of swell clay and frost
on the reduction of serviceability were not included . If problems of swell clay and frost
heave are significant in a given region and have not been properly corrected, the loss of
heave are significant in a given region and have not been properly corrected, the loss of
serviceability over the analysis period should be estimated and added to that due to
serviceability over the analysis period should be estimated and added to that due to
cumulative traffic loads . Figure 11.23 shows the serviceability loss versus time curves
cumulative traffic loads . Figure 11.23 shows the serviceability loss versus time curves
for a specific location .
for a specific location .
Yoder; E. J. and M. W. Witczak, “Principles of Pavement Design”, A
Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
11.3 AASHTO METHOD
11.3 AASHTO METHOD
11 .3.1 Design Variables
11 .3.1 Design Variables
Yoder; E. J. and M. W. Witczak, “Principles of Pavement Design”, A
Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
11.3 AASHTO METHOD
11.3 AASHTO METHOD
11 .3.1 Design Variables
11 .3.1 Design Variables
T
T
he environmental loss
he environmental loss
is a summation of losses from both
swelling
swelling
and
frost
frost
heave
heave
. The chart may be used to estimate the serviceability loss at any intermediate period,
for example, a loss of 0 .73 at the end of 13 years . Of course,
if only swelling or frost heave
if only swelling or frost heave
is considered, there will be only one curve on the graph
is considered, there will be only one curve on the graph
.
The shape of these curves
The shape of these curves
indicates that the serviceability loss due to environment increases at a decreasing rate.
indicates that the serviceability loss due to environment increases at a decreasing rate.
This
may favor the use of stage construction because most of the loss will occur during the first
stage and can be corrected with little additional loss in later stages.
Yoder; E. J. and M. W. Witczak, “Principles of Pavement Design”, A
Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
11.3 AASHTO METHOD
11.3 AASHTO METHOD
11 .3.1 Design Variables
11 .3.1 Design Variables
S
S
erviceability
erviceability
Initial and terminal serviceability indexes must be established to
compute
the change in serviceability, APSI
the change in serviceability, APSI
, to be used in the design equations . The initial
serviceability index is a function of
pavement type
pavement type
and
construction quality
construction quality
.
Typical values from the AASHO Road Test were
4.2 for flexible pavements
4.2 for flexible pavements
and
4.5 for rigid
4.5 for rigid
pavements.
pavements.
is the lowest index that will be tolerated before
rehabilitation, resurfacing, and reconstruction
become necessary.
The terminal serviceability index
The terminal serviceability index
Yoder; E. J. and M. W. Witczak, “Principles of Pavement Design”, A
Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
11.3 AASHTO METHOD
11.3 AASHTO METHOD
11 .3.1 Design Variables
11 .3.1 Design Variables
For relatively minor highways where economics dictate a minimum initial
capital outlay, it is suggested that this be accomplished by reducing the design
period or total traffic volume, rather than by designing a terminal serviceability
index less than 2.0 .
An index of 2.5 or higher is suggested for design of major
An index of 2.5 or higher is suggested for design of major
highways and 2.0 for highways with lower traffic
highways and 2.0 for highways with lower traffic
.
.
Yoder; E. J. and M. W. Witczak, “Principles of Pavement Design”, A
Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
Structural Design of Highway
Structural Design of Highway
Dr. Rana Amir Yousif & Dr. Abeer K. Jameel
Dr. Rana Amir Yousif & Dr. Abeer K. Jameel
The structural design of highway pavements involves principles and methods for flexible pavement design, as outlined by AASHTO. Factors like performance period, analysis period, and maintenance levels play crucial roles in optimizing pavement structure longevity and performance. Various references, including the work of Yoder & Witczak, contribute to the understanding and implementation of pavement design techniques.
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Presentation Transcript
Structural Design of Highway Flexible Pavement Design Highway and Transportation Engineering Al-Mustansiriyah University 2019-2020 Dr. Rana Amir Yousif & Dr. Abeer K. Jameel Yoder; E. J. and M. W. Witczak, Principles of Pavement Design , A Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
References Nicholas J. Garber and Lester A. Hoel. Traffic and Highway Engineering , Fourth Edition. Yoder; E. J. and M. W. Witczak, Principles of Pavement Design , A Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975. Yaug H. Huang, Pavement Analysis and Design , Prentic Hall Inc., U.S.A., 1993. AASHTO Guide for Design of Pavement Structures 1993 , AASHTO, American Association of State Highway and Transportation Officials, U.S.A., 1993. Oglesby Clarkson H., HighwayEngineering , John Wiley & Sons Inc., U.S.A., 1975. Yoder; E. J. and M. W. Witczak, Principles of Pavement Design , A Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
AASHTO METHOD The design procedure recommended by the American Association of State Highway and Transportation Officials (AASHTO) is based on the results of the extensive AASHO Road Test conducted in Ottawa, Illinois, in the late 1950s and early 1960s . The AASHO Committee on Design first published an interim design guide in 1961 . It was revised in 1972 and 1981 . In 1984-85, the Subcommittee on Pavement Design and a team of consultants revised and expanded the guide under NCHRP Project 20-7/24 ; they issued the guide in 1986 . The guide was revised in 1993 with practically no change in the design method presented in this section . Yoder; E. J. and M. W. Witczak, Principles of Pavement Design , A Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
11.3 AASHTO METHOD 11 .3.1 Design Variables Several general design variables related to both flexible and rigid pavements are presented in this section . Time Constraints To achieve the best use of available funds, the AASHTO design guide encourages the use of a longer analysis period for high-volume facilities, including at least one rehabilitation period . Thus, the analysis period should be equal to or greater than the performance period, as described below. Performance Period The performance period refers to the time that an initial pavement structure will last before it needs rehabilitation or the performance time between rehabilitation operations . It is equivalent to the time elapsed as a new, reconstructed, or rehabilitated structure deteriorates from its initial serviceability to its terminal serviceability. Yoder; E. J. and M. W. Witczak, Principles of Pavement Design , A Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
11.3 AASHTO METHOD 11 .3.1 Design Variables The designer must select the performance period within the minimum and maximum allowable bounds that are established by agency experience and policy. Note The selection of performance period can be affected by such factors: The functional classification of the pavement. The type and level of maintenance applied. The funds available for initial construction. Life cycle costs. and other engineering considerations. Yoder; E. J. and M. W. Witczak, Principles of Pavement Design , A Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
11.3 AASHTO METHOD 11 .3.1 Design Variables Analysis Period The analysis period is the period of time that any design strategy must cover . It may be identical to the selected performance period performance limitations may necessitate the consideration of staged construction or planned rehabilitation for the desired analysis period . Table 11.13 contains general guidelines for the length of the analysis period . .However, realistic Yoder; E. J. and M. W. Witczak, Principles of Pavement Design , A Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
11.3 AASHTO METHOD 11 .3.1 Design Variables Traffic:The design procedures are based on cumulative expected 18-kip (80-kN) equivalent single-axle load (ESAL) . If a pavement is designed for the analysis period without any rehabilitation or resurfacing, all that is required is the total ESAL over the analysis period . However, if stage construction is considered and rehabilitation or resurfacing is anticipated, a graph or equation of cumulative ESAL versus time is needed so that the ESAL traffic during any given stages can be obtained . Note Yoder; E. J. and M. W. Witczak, Principles of Pavement Design , A Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
11.3 AASHTO METHOD 11 .3.1 Design Variables Reliability:The design procedures are based on cumulative expected 18-kip (80-kN) equivalent single-axle load (ESAL) . Yoder; E. J. and M. W. Witczak, Principles of Pavement Design , A Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
11.3 AASHTO METHOD 11 .3.1 Design Variables Application of the reliability concept requires the selection of a standard deviation that is representative of local conditions . It is suggested that standard deviations of 0 .49 be used for flexible pavements and 0 .39 for rigid pavements. These correspond to variances of 0 .2401 and 0 .1521, which are nearly the same as those shown in Table 10.12 .. When stage construction is considered, the reliability of each stage must be compounded to achieve the overall reliability ; that is, (11.28) in which n is the number of stages being considered . For example, if two stages are contemplated and the desired level of overall reliability is 95%, the reliability of each stage must be (0 .95) ^1/2 , or 97.5% . Yoder; E. J. and M. W. Witczak, Principles of Pavement Design , A Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
11.3 AASHTO METHOD 11 .3.1 Design Variables Environmental Effects :The AASHO design equations were based on the results of traffic tests over a two-year period . The long-term effects of temperature and moisture on the reduction of serviceability were not included . If problems of swell clay and frost heave are significant in a given region and have not been properly corrected, the loss of serviceability over the analysis period should be estimated and added to that due to cumulative traffic loads . Figure 11.23 shows the serviceability loss versus time curves for a specific location . Yoder; E. J. and M. W. Witczak, Principles of Pavement Design , A Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
11.3 AASHTO METHOD 11 .3.1 Design Variables Yoder; E. J. and M. W. Witczak, Principles of Pavement Design , A Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
11.3 AASHTO METHOD 11 .3.1 Design Variables The environmental loss is a summation of losses from both swelling and frost heave . The chart may be used to estimate the serviceability loss at any intermediate period, for example, a loss of 0 .73 at the end of 13 years . Of course, if only swelling or frost heave is considered, there will be only one curve on the graph . The shape of these curves indicates that the serviceability loss due to environment increases at a decreasing rate. This may favor the use of stage construction because most of the loss will occur during the first stage and can be corrected with little additional loss in later stages. Yoder; E. J. and M. W. Witczak, Principles of Pavement Design , A Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
11.3 AASHTO METHOD 11 .3.1 Design Variables ServiceabilityInitial and terminal serviceability indexes must be established to compute the change in serviceability, APSI, to be used in the design equations . The initial serviceability index is a function of pavement type and construction quality . Typical values from the AASHO Road Test were 4.2 for flexible pavements and 4.5 for rigid pavements. is the lowest index that will be tolerated before rehabilitation, resurfacing, and reconstruction become necessary. The terminal serviceability index Yoder; E. J. and M. W. Witczak, Principles of Pavement Design , A Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
11.3 AASHTO METHOD 11 .3.1 Design Variables An index of 2.5 or higher is suggested for design of major highways and 2.0 for highways with lower traffic. For relatively minor highways where economics dictate a minimum initial capital outlay, it is suggested that this be accomplished by reducing the design period or total traffic volume, rather than by designing a terminal serviceability index less than 2.0 . Yoder; E. J. and M. W. Witczak, Principles of Pavement Design , A Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
Structural Design of Highway Dr. Rana Amir Yousif & Dr. Abeer K. Jameel Yoder; E. J. and M. W. Witczak, Principles of Pavement Design , A Wiley- Interscience Publication, John Wiley & Sons Inc., U.S.A., 1975.
