HomeMy WebLinkAboutORDINANCE - 444 - 9/27/1966 - STREET PAVING STANDARDSORDINANCE NO. 444
AN ORDINANCE AMENDING THE MUNICIPAL CODE
OF ELK GROVE VILLAGE RELATING TO STREET
PAVEMENT STANDARDS
NOW, THEREFORE, BE IT ORDAINED by the President and
Board of Trustees of the Village of Elk Grove Village,
Counties of Cook and DuPage, Illinois:
page 55b2,55c and a portion of 55d relating to
Section 1. That Section 8.005/(Street pavement) of
the Municipal Code of Elk Grove Village be and is hereby
amended to read as follows:
STREET PAVEMENT STANDARDS
1. All street pavements within the subdivision shall be designed
in accordance with the structural design procedures and the minimum
requirements contained in the following manuals:
a) Manual for the Structural Design of Portland Cement Concrete
Pavements in Illinois, Revised February, 1965, issued the
Division of Highways, Department of Public Works and Buildings,
State of Illinois.
b) Manual of Instructions for the Structural Design of Bituminous
Revised November, 1964 and issued by the Division of Highways,
Department of Public Works and Buildings, State of Illinois.
A copy of all design assumptions and computations on which the
proposed design is based shall be submitted to the Village Engineer
for review and approval.
2. All streets within the subdivision shall be constructed to one
of the following alternate standards:
a) Portland cement concrete pavement with integral curbs,
constructed in compliance with "Special Provision for Portland
Cement Concrete Pavement (Special) BLR M-640 (5-64) and
"Special Provision for Integral Concrete Curb" BLR M-641
(5-64) issued by the Division of Highways, Department of Public
Works and Buildings, State of Illinois.
b) Portland cement concrete pavement with combination curb
and gutter, constructed in compliance with Section 48 and
Section 80 of "Standard Specifications for Road and Bridge
Construction" adopted January 2, 1958 by the Division of
Highways, Department of Public Works and Buildings, State
of Illinois, and Supplemental Specifications thereto, effective
January 3, 1966.
c) Bituminous concrete pavement with concrete curb and
gutter.
The bituminous concrete binder course shall have a
minimum compacted thickness of 1 1/2 inches and the
bituminous concrete surface course shall have a mini-
mum compacted thickness of 1 inch. The binder course
and surface course shall be constructed in compliance
with either Section 44 or Section 46 of Standard Speci-
fications for Road and Bridge Construction. adopted by
The Division of Highways, Department of Public Works
and Buildings, State of Illinois, and Supplemental
Specifications thereto, effective January 3, 1966.
The concrete curb and gutter shall be constructed in
compliance with Section 80 of said specifications."
The bituminous concrete binder and surface courses shall
be laid upon one of the following alternate base courses:
1) Waterbound macadam base course, constructed in
accordance with Section 30 of the Standard Specifications
referred to above.
2) Soil -cement base course, constructed in accordance
with Section 31 of the Standard Specifications referred to
above.
3) Portland cement concrete base course constructed in
compliance with Section 32 of the Standard Specification
referred to above.
4) Pozzolanic base, Type A, constructed in compliance
with specifications for same, adopted April 1, 1964 by
the Division of Highways, Department of Public Works and
Buildings, State of Illinois, and revised April 15, 1966.
The minimum width of the paved roadway, back to back of curb,
shall be as follows:
1. On residential streets, not less than twenty-eight feet.
2. On major streets, not less than thirty-six feet.
3. On streets through business and shopping areas, not less
than sixty-six feet.
4. On streets through commercial areas, not less than forty
feet.
5. On streets through industrial areas, not less than forty
feet.
Before any paving work is commenced all street grading shall
be properly completed as shown on grading plan submitted with final plat
of subdivision.
The underground work, such as sewer, water, house service con-
nections therewith and all related backfilling and compaction of
trenches shall be completed before any paving work is commenced.
Section 2. This ordinance shall be in ful orc $na
effect from and after its passage and approval�ac o lition
to law.
PASSED this �7thday of
September 1966
APPROVED this 27thday of September 1966
Jack D. Pahl
President
Attest:
Eleanor G. Turner
Village Clerk
Published this 6th day of October 1966 in the Elk Grove Herald and
DuPage County Register.
A�,
/ State of Illinois
G DEPARTMENT OF PUBLIC WORKS AND BUILDINGS
Division of Highways
MANUAL FOR THE STRUCTURAL
DESIGN OF
PORTLAND CEMENT CONCRETE PAVEMENTS
IN ILLINOIS
Bureau of Design
December 1964
.Revised February 1965
kcCE:.t'J::
0� o -
DEFINITION OF TERMS
Pavement Structure - the combination of sub -base, base course,
and surface course placed on a subgrade to support the traffic load and
distribute it to the roadbed.
Portland Cement Concrete Pavement - a pavement structure which
distributes loads to the subgrade having as one course a Portland cement
concrete slab of relatively high bending resistance.
Roadbedl - the graded portion of a hichway within top and side
slopes, prepared as a foundation for the pavesfft structure and shoulder.
Subgrade_1l - the top surface of a roadbed upon which the pavement
structure and shoulders are constructed.
Sub -base - the layer or layers of specified or selected material
of design thickness placed on a subgrade to support the rigid slab.
Pum in 1 - the ejection of foundation material, either wet or dry,
through joints or cracks or along edges of rigid slabs, due to vertical move-
ments of the slab under traffic.
Single Units - single unit commercial vehicles having either two
or three axles.
Multiple Units - truck tractor semi -trailers, truck full trailer
combination vehicles, and other combinations.
Single Axle - an assembly of two or more wheals, whose centers
are in one transverse vertical plane or may be included between two parallel
transverse vertical planes 40 inches apart extending across the full width
of the vehicle.
Tandem Axle -1/ - any two or more consecutive axles whose centers are
more than 40 inches but not more than 96 inches apart, and are individually
attached to and/or articulated from a common attachment to the vehicle includ-
ing a connecting mechanism designed to equalize the load between axles.
M AASHO Highway Definitions (1962),
Axle Load" - the total load transmitted to the pavement by either
a single or tandem axle, usually expressed in kips (1000 pounds).
Single Axle Load - the total load transmitted to the road by a
single axle when spaced more than 8 feet from the center of the next nearest
axle.
Tandem Axle Load I/ - the total load transmitted to the road by two or
more consecutive axles whose centers may be included between parallel transverse
vertical planes spaced more than 40 inches and not more than 96 inches apart,
extending across the full width of the vehicle.
Time -Traffic Exposure Factor - a numerical factor applied to the
rigid slab thicknesses indicated by the Road Test performance equation to
modify the equation to be more nearly representative of the behavior of pave-
ments serving under similar conditions but over periods of time more typical
of regular service life.
Equivalency Factor - a numerical factor that expresses the relation-
ship of a given axle -load to another axle -load in"terms of their effect on the
serviceability of a pavement structure. In this policy, all axle -loads are
equated in terms of equivalent 18 -kip single axle -load applications.
Traffic Factor (Rigid) - the total number of 18 -kip equivalent single axle -
load applications anticipated during the design period, expressed in millions,
t
Class I Roads and Streets - roads and streets designed as a four -or
more -lane facility, or as part of a future four -or more -lane facility, and
one-way streets with a structural design traffic greater than 3500 ADT.
Class II Roads and Streets - roads and streets designed as a two-lane
facility with structural design traffic greater than 1000 ADT and all one-way
streets with a structural design traffic less than 3500 ADT.
Class III Roads and Streets - roads and streets with structural design
traffic of 1000 ADT or less.
Structural Design Period - the number of years that a pavement is
to carry a specific traffic volume and retain a serviceability level at or
above a designated minimum value.
Structural Design Traffic - the average daily traffic esr_mated ?or
the year representing one half of the deeign period.
Design Lane - the lane carrying the greatest number of single and
multiple units.
- iv-
INTRODUCTION
Since the completion of the AASHO Road Test Project, the Illinois
Division of Highways has been Studying the results and doing research directed
towards developing practical applications of the findings. The findings of
the rigid pavement research conducted on the test/Project, research studies
conducted by the Division together with its e4erience and judgement, and
recommendations of the AASHO Committee on Design have culminated in the
development of "An Interim Policy on Structural Design of Portland Cement
Concrete Pavements in Illinois."
This Manual for the "Structural Design of Portland Cement Concrete
Pavements in Illinois" has been prepared from the information contained in
the "Interim Policy." The procedures presented in the Manual establish a
means of determining the structural design of a portland cement concrete pave-
ment so that it will be capable of carrying a specific volume and composition
of mixed passenger car and truck traffic at or above a designated minimum level
of service for a specified period of time.
The Manual covers the factors that must be considered in developing
the structural design. These factors include the volume and composition of
traffic, the length of time the pavement is to carry the traffic, and the
strength characteristics of the roadbed soils. The procedures presented in
this Manual are applicable to developing the structural design of both standard
reinforced and continuously reinforced Portland cement concrete pavements in
Illinois.
The AASHO Road Test Rigid Pavement Performance Equation serves as
the basis of this design procedure. The equation explains performance of the
test sections as related to pavement design, the magnitude and configuration
of the axle load, and the number of axle load applications. This equation is
necessarily limited to the physical environment of the project; to the materials
used in the test pavements; to the range in pavement thicknesses included in the
- 1 -
experiment; to the axle loads, number of axle load applications, and the
specific times and rates of application of the test traffic; to the con-
struction techniques employed; and to the climatic cycles experienced during
construction and testing of the experimental facility.
To apply the equatibn in the design of regular highway pavements,
it is necessary to make certain assumptions and extrapolations based on
experience and engineering judgement. In developing the design procedure,
modifications were made in the rigid pavement performance equation to reflect
the'effect of the following variations on pavement performance.
(1) Mixed traffic and passenger car traffic axle loadings
when compared with controlled traffic axle loadings on
the road test.
(2) Pavements subjected to traffic over long periods of time
when compared to the two years of traffic on the road
test.
(3) Variations in the support strengths of the roadbed soils.
Variations in climatic conditions as they exist from one part of the State to
another and particularly between the extreme northern'and extreme southern
portions undoubtedly affect pavement performance. The relative effects of
these variations on pavement performance however, are not sufficiently dis-
tinguishable at the present time to be taken into account in pavement struc-
tural design. Therefore, in developing the structural design procedure in
this Manual, climatic effects were considered only on a State-wide basis.
As additional knowledge is gained through further research and
experience, the precision of these assumptions and extrapolations should
become sharpened. Therefore, the design procedure in this Manual is pro-
visional in nature, and is subject to modification based on additional ex-
perience and research.
- 2 -
DEVELOPMENT OF DESIGN PROCEDURE
The design of a pavement structure requires the compilation of
many factors. Following is a brief description of the factors included in
the development of the design procedure. Detailed information on the develop-
ment may be found in "An Interim Policy on the Structural Design of Portland
Cement Pavements in Illinois", dated May, 1964.
Structural Design Traffic
The structural design traffic is the estimated average daily traffic
for the year representing 1/2 of the structural design period. The structural
design period for all Portland cement concrete pavements is 20 years. For
example, when the anticipated construction date of a highway is 1965, the
structural design traffic will be an estimate of the average daily traffic
projected to the year 1975.
The structural design traffic is estimated from current traffic
classification count data obtained from traffic maps published by the Illinois
Division of Highways, or by visual classification counts if traffic maps are not
available on traffic maps for Class III roads and streets, an estimate of these
volumes may be made by using the following percentages of total ADT; passenger
cars 80, single units 19, and multiple units 1.
While the structural design traffic represents an estimate of the
projected average daily traffic that will be carried by the highway facility,
the pavement structural design will be based on that lane carrying the greatest
number of single and multiple units (design lane). The number of vehicles per day
in the design lane may be estimated by multiplying the structural design traffic
by the appropriate distribution factor from the table on Page 4.
These distribution factors are based on traffic placement studies
of average conditions. In some cases unusual traffic controls or design
features will influence lane usage and special placement studies will be
MW
required. Examples of such cases would be the restriction of commercial
vehicles to 4 .lanes of a 6 -lane facility or close interchange ramp spacing.
No. Lanes in
Pavement
Facility
STRUCTURAL DESIGN TRAFFIC
Per Cent of Single and Multiple Per Cent of Passenger
Units in Design Lane
Cars in Design Lane
2 or 3*
50
-, 50
4
45
32
6 or more
40
20
* One-way streets
Mixed Traffic Axle Loadings
To evaluate the effects of mixed traffic axle loadings on pavement
performance, a system was developed to convert these loadings into a "traffic.
factor." The traffic factor is the total number of equivalent 18 kip (18,000
pound) single axle load applications, expressed in millions, that a given
pavement may be expected to carry throughout its entire service life.
In developing this system, use was made of "equivalency factors"
for various groupings of single and tandem axle loadings determined from the
road test equation and State-wide loadometer survey data and classification
counts at loadometer stations dating back to 1936, and as recent as 1962.
The equivalency factor for any given single or tandem axle load expresses the
number of 18 kip single axle load applications that is equivalent in effect
upon pavement performance to one application of the given axle load.
- 4 -
In determining the number of 18 kip equivalent single axle loads
which represent one application of each of the three classes of vehicles,
consideration must be given to the differences in average axle weights of
both single unit and multiple unit trucks operating on the various highways
ranging from high volume major highways, with heavy commercial truck traffic,
to low ,volume farm to market highways. Highways were divided into three
generalclassifications to reflect these differences in average axle loads.
The 18 kip single axle load application per vehicle classification determined
for Class I, Class II, and Class III roads and streets are as follows:
ROAD AND STREET 18 -KIP EQUIVALENT S.A.L. APPLICATIONS PER VEHICLE
CLASSIFICATION Passenger Cars Single Units Multiple Units
Class
I
0.0004
0.123
1.155
Class
II
0.0004
0.123
1.134
Class
III
0.0004
0.123
1.134
These values were used to develop the traffic factor equations
contained in Table 2.
Roadbed Soils
An A-6 (9-13) type of roadbed soil was used throughout the entire
embankment of the AASHO Road Test Project. Since only one soil type was
taken into consideration in the AASHO Test, it was necessary to modify the
road test equation so that pavement thicknesses could be developed for other
types,of,soil. The modification makes use of the California Bearing Ratio
(CBR) 'value of the soil which is the only soil support value normally deter-
mined by theIllinoisDivision of Highways. Other soil strength test pro-
cedures can be used provided that test results can be correlated with those
obtained by the CBR test procedure used by the Illinois Division of Highways.
The soils support CBR values selected for use by the designer should
represent a minimum value for the soil to be used. Preferably laboratory tests
- 5 -
should be made on four-day soaked samples of.the soils to be used in con-
struction. It is recommended that a soil survey be made prior to all con-
struction; however, when test data are not available, the following values
are suggested:
Soil Classification CBR Value
A-1 20
A-2-4, A-2-5 15
A-2-6, A-2-7 12
A-3 10
A-4, A-5, A-6 3
A-7-5, A-7-6 2
Time -Traffic Exposure Factor
Studies of the performance of existing Illinois pavements serving
over long,periods of time indicated that the Road Test equation, which was
based on short-term tests, needed to be modified to be more representative of
the performance of pavements in regular service. To modify the Road Test
equation, a numerical factor known as the Time -Traffic Exposure factor is
applied to the slab thickness. This modification is incorporated in the type
and thickness scale shown on Charts 1 and 2.
Structural Design
Graphic presentations of the AASHO Road Test rigid pavement equation
as modified for Illinois use are shown as nomographs in Charts 1 and 2. The
nomographs include a scale of traffic factors representing total 18 -kip equi-
valent single axle -load applications, a soil support scale, and pavement type
and thickness scales for different classifications of roads and streets.
The pavement thickness scales in Charts 1 and 2 include both standard
reinforced and continuously reinforced portland cement concrete pavements. A
correlation of the thicknesses of the two types of pavement was developed
through a study of the performance data from Illinois pavements.
The pavement thickness is determined from Charts 1 or 2 by the
following procedure; (1) pass a line through the estimated traffic factor
(18 -kip single axle -load applications), Scale a, and the CBR value of the
roadbed soil, Scale b, (2) read the pavement thickness and type ar the point
of intsrse'ction with Scale c, and (3) when the analysis indicates a slab
thickness 0.3 inch or less over an even inch, the design thickness shall be
the even inch; when the analysis indicates a slab thickness more than 0.3 inch
over an even inch, the next higher full inch shall be used (e.g., for 8.3 inches
use 8.0 inches, and for 8.4 inches use 9.0 inches).
General
LIMITATIONS AND REQUIREMENTS
The structural design method described herein enables the designer
to determine the type and thickness of a portland cement concrete pavement
required to give satisfactory performance while carrying a given volume of
mixed traffic. There are certain limitations and requirements, however, which
must be"followed to assure the adequacy of the design under the traffic it is
intendedi to carry.
The material requirements, concrdte-mix�esign, and construction
procedures and controls are to be in accordance with the current specifications
and practices of the Illinois Division of Highways. In order to assure satis-
factory performance, the minimum strengths for the roadbed soils and the pave-
ment structure determined for the design must be obtained during construction.
The design period may or may not be the actual service life of the
pavement. The actual service life may be longer or shorter than the design
period depending upon the conditions under which the pavement actually serves
and conditions given for the design. Highly significant are the differences
between the structural design traffic and the actual traffic carried by the
pavement, and the difference between the design terminal serviceability level
and the actual serviceability level at which the pavement is retired from
service. -
The structural design as determined by the described method is
capable of carrying the structural design traffic for the selected design
period. At the end of the design period, the serviceability level of the
pavement can be expected to have been reduced to a value of 2.5 for Class I
roads and streets and to 2.0 for Class II and Class III roads and streets, and
the pavement should be considered eligible for retirement.
The terminal serviceability level of 2.0 is the average level at
which pavements are being retired throughout the nation. This level was
determined by a survey conducted in 1961 by the Bureau of Public Roads in
cooperation with the State Highway Departments at the request of the AASHO
Committee on Highway Transport. A study of the terminal serviceability level
of highway pavements in Illinois has fairly well substantiated this as an
average value. However, pavements of four -lane divided expressways are being
retired at serviceability levels above 2.0 and generally in the range of 2.5
to 3.0. For these reasons, the design requirements have been based on a
terminal serviceability level of 2.5 for Class I roads and streets, and 2.0 for
Classes II and III.
Traffic and Loads
The equations used for converting structural design traffic into
equivalent 18 -kip single axle=load applications are based on a State-wide
average distribution of vehicle types and axle loadings, and are directly
applicable to most roads and streets. However, cases will arise in which
these equations cannot be used, and a special analysis will be necessary.
One such case would be that involving a highway adjacent to an industrial site
where the commercial vehicles entering and leaving the site generally travel
empty in one direction and fully loaded in the other. Such a case should be
referred to the Bureau of Design and the Bureau of Research and Development
for special analysis. It will be necessary for the Districts to furnish these
- 8 -
Bureaus with the structural design traffic and loadometer and classification
count data in sufficient detail to permit a determination of the distribution
of commercial vehicle types and the single enu cnnaem axle loadings within
each type.
Roadbed Soils
The performance of a portland cement concrete pavement is directly
related to the physical properties and supporting power of the roadbed soils.
Some soils have a detrimentalleffect on performance that cannot always be
overcome by increasing slab thickness. The problems that can arise as a
result of the various properties of roadbed soils, such as permanent deforma-
tion, excessive deflection and rebound, excessive volume changes, and frost
susceptibility need to be recognized in the design stage.
In some instances "pockets" of soil may be encountered which are
suitable for roadbeds but which have a CBR value less than that used to
determine the pavement thickness. Since the pavement thickness is "rounded"
to the even inch, the design may be adequate when the disparity in soil support
is slight. This may be determined by using the reduced CBR value and solving
for pavement thickness from Chart 1 or 2. When the soil has a support value
that is inadequate for the design thickness, it shall be replaced by a
material having a satisfactory CBR value. Provisions for the solution of
these problems must be included in the plans and specifications.
Structural Design
Sub -base Type and Thickness - The sub -base of a portland cement
concrete pavement shall consist of a compacted layer of stabilized material
placed between the subgrade and the slab for the prime purpose of minimizing
pumping of the roadbed soils.
Sub -base thickness was excluded as a variable in the AASHO Road Test
performance equation. An analysis of the results of the test demonstrated
that variations of between 3 and 9 inches in sub -base thickness had no signi-
ficant effect on the performance of the test pavements. The performance of
MM
sections of pavement having a subbase, however, was superior to that of
sections having the same slab thickness without a subbase.
Subbase thickness has not been included as a design variable in
this policy. However, the design procedure has been developed on the basis
of an asgiimption that a subbase will be used beneath all portland cement
concrete slabs. The only unconditional exception to the assumption includes
those streets with curbs and gutters and storm sewer systems that are to serve
only residential traffic, for which the subbase may be omitted at the option
of the designer. There are two conditional exceptions. They are (1) those
designs proposed for streets that have curbs and gutters and storm sewer
systems and are to be constructed on an existing roadbed that is not to be
appreciably disturbed during the new construction, and (2) those proposed
designs for Class II or Class III roads and streets at locations having roadbed
soils that are of a quality equal to the standard granular subbase require-
ments.
The minimum requirements for type and thickness of subbase are
given,in Table 1. To provide a subbase that will be less susceptible to
pumping, it is specified that only stabilized granular materials be used.
Pavement Type and Thickness - The type and thickness needed to carry
the structural design traffic for the selected design period are obtained
directly from either Chart 1 or Chart 2. However, the minimum requirements
given in Table 1 for type and thickness of pavement must not be violated. To
insure against impractical and inadequate designs, the following basic rules
have been established as a guide for the designer while using Charts 1 and 2;
(1) when the analysis indicates a design that is less than the minimum -require -
menta given in Table 1, the structural design shall be based on the minimum
requirements, (2) when the analysis indicates a slab thickness greater than
nine,inchea'for standard reinforced portland cement concrete, the selected
design shall be based on the use of continuously reinforced portland cement
concrete.
- 10 -
Occasional analyses will show that, for Class III roads and streets,
a thickness of pavement less than the established eight -inch minimum will be
adequate for the axle loadings anticipated to be carried by the pavement. The
ninimucr.?recuirement has been set to cover the unpredictable usage of th=
pavement�by drivers of heavy commercial vehicles on their erroneous assumption
that all concrete pavements are constructed for heavy-duty service, regardless
of location.
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Table 2 - Traffic Factor Equations
Class I Roads and Streets - roads and streets designed as a four- or
more -lane facility, or as part of a future four- or more -lane facility, and
one-way streets with a structural design traffic greater than 3500 ADT.
TF - 20(0.146 x Up x PC + 44.895 x US x SU + 421.575 x UM x MU)
1,000,000
Class II Roads and Streets - roads and streets designed as a two-lane
facility with structural design traffic greater than 1000 ADT and all one-way
streets with a structural design traffic less than 3500 ADT.
o:
Class III Roads and Streets - roads and streets with structural design
traffic of 1000 ADT or less
TF - 20(0.146 x Up x PC + 44.895 x US x SU + 413.910 x UM x MU)
1,000,000
where: PC - average daily pass6nger car traffic
SU - average daily single unit traffic
MU - average daily multiple unit traffic
Up - percent passenger cars in design lane
US percent single units in design lane
UM - percent multiple units in design lane
- 13 -
CHART-
PORTLAND CEMENT CONCRETE PAVEMENTS
CLASS I ROADS a STREETS
40
30
20
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
(a)
0
- 14 -
(c)
z
U)
7 a7
w
z
Y
U_
F-
F -
z
8 w
2
w
U
9
z
W7
Y
U_ _
F-
F- 8
w
050
K500
W
d
>>
a7 20
23o
2`00
a
10
O
�g0
N 9
2
N
(bl
- 14 -
(c)
z
U)
7 a7
w
z
Y
U_
F-
F -
z
8 w
2
w
U
9
CHART --2
PORTLAND CEMENT CONCRETE PAVEMENTS
CLASS II &III ROADS AND STREETS
40L— 6—t
3
20
10
9
8
7
6
5
U
ZMLI
LL.
LL.
d 2
H
0.3
(a)
� �gR
K
a0- 50 5p0
N 20 2.000
JY 1 ) 14$
N 2 107 0
(b)
- 15 -
Co
cf) 7
w
z
Y
U_
H
z
8
w
w
o: 9
+.:
7 w
z
Y
E-
r
APPLICATION OF DESIGN METHOD
The design method enables the designer to determine the type and
thickness of pavement required to carry a specific volume of mixed traffic
fdr a designated period of time and retain a Serviceability level at or above
a designated minimum value.
The application of the method involves the following determinations
and procedures.
1. Determine the following volumes pro}acted to 10
l�
years beyond the date of construction.
a. Average daily passenger car traffic - PC.
b. Average daily single unit traffic - SU.
c. Average daily multiple unit traffic - MU.
2. Determine the percent of structural design traffic
to be carried by the design lane using the percentage
distribution factors from Page 4 or placement studies.
a. Percent passenger cars in design lane - Up.
b. Percent single units in design lane . US.
c. Percent multiple units in design lane a UM.
3. Determine classification of road or street - See
Table 2
4. Calculate traffic factor (TF) using pertinent formula
from Table 2.
5. Determine California Bearing Ratio (CBR) of roadbed
soil.
6. Using the TF and the CBR find pavement type and thickness
(D) from Chart 1 for Class I roads and streets, or Chart 2
for Class II or III roads and streets. When D is 0.3 inch
- W-
or less over an even inch, use the even inch. When D is
more than 0.3inch over an even inch, use the next higher
full inch.
Compare the thickness determined from Chart 1 or 2 with the
minimum structural requirements contained in Table 1, and
use the larger of the two thickness values for design pur-
poses.
8. Provide subbase in accordance with Table 1.
Design Examples
1. Problem - Determine the type and thickness of a pavement that will satisfy
the following conditions:
A. 4 -lane rural highway
B. 22,300 total average daily traffic 10 years from date
of construction.
Traffic comprised of:
1. 20,000 passenger cars
2. 1,000 single units
3. 1,300 multiple units
C. Soil Support CBR value - 3.0
solution
A. Determine percent of structural design -•-":ic in design
lane. From the table on Page 4, it is found that, for a
rural 4 -lane highway, 45 percent of the single and multiple
units and 32 percent of the passenger cars will be in the
design lane. Therefore:
1. Up . 0.32
2. Us . 0.45
3. UM . 0.45
- 17 -
B. Determine the Traffic Factor using the equation for
Class I Roads and Streets from Table 2.
TF m 20(0.146 x 0.32 x 20,000 + 44.895 x 0.45 x 1000 + 421.575 x 0.45 x 1300)
1,000,000
5_4
C. Determine slab type and thickness from Chart 1. Enter chart
at .5.4 on Traffic Factor Scale and project a straight line
through CBR - 3.0 on the soil support scale to intersect the
thickness scale. The point of intersection shows that a
7.2 -inch continuously reinforced concrete pavement is required.
This value will be rounded to 7 inches and a 7 -inch continuously
reinforced pavement will be used.
D. The minimum structural design requirements for Class I Roads
and Streets contained in Table 1 show that the determined
thicknesses are satisfactory.
2. Problem - Determine the type and thickness of a pavement that will
satisfy the following conditions:
A. 2 -lane, two-way, urban street
B. 8,500 total average daily traffic 10 years beyond date
of construction comprised of:
1. 7,900 passenger care
2. 450 single units
3. 150 multiple units
- 18 -.
C. Soil Support value - 3.5.
Solution
A. 50 percent of the structural design traffic will be in the
design lane. Therefora:
1. Up - 0.50
2. US - 0.50
31. UM - 0.50
B. Determine the Traffic Factor using the equation for Class II
Roads and Streets from Table 2.
TF - 20(0.146 x 0.50 x 7.900 + 44.895 x 0.50 x 450 + 413.910 x 0.50 x 150)
1,000,000
- 0.83
C. Determine slab type and thickness from Chart 2 using TF - 0.83
and CBR = 3.5. The point of intersection on the thickness scale
shows that a 7.25 -inch standard reinforced pavement is required.
The 7.25 chart thickness is rounded to 7 inches.
D. Since the 7 -inch "rounded" thickness value is less than the
8 -inch minimum value for Class II Roads and Streets from
Table 1, use the 8 -inch thickness for design purposes.
3. Problem - Determine the type and thickness of a pavement that
will sat-isfy the following conditions:
A. 6 -lane urban expressway
B. 45,000 total average daily traffic 10 years from date
of construction comprised of:
1. 40,000 passenger cars
2. 2,800 single units
3. 2,200 multiple units
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C. Placement studies indicate that, due to the close
spacing of interchange ramps on such facilities, 43 .
percent of the single and multiple units, and 25 percent
of the passenger care will be in the design lane.
D.. The soil support CBR value - 10.0. Scattered pockets
of soil are encountered which have a CBR value of 2.0.
Solution
A. As determined by the placement studies:
1. Up - 0.25
2. US - 0.43
3. UM - 0.43
B. The Traffic Factor determined from the equation in Table 2 for
Class I Roads and Streets is:
TF - 20(0.146 x 0.25 x 40,000 + 44.895 x 0.43 x 2,800 + 421.575 x 0.43 x 2,200)
1,000,000
- 9.1
C. Determine slab type and thickness from Chart 1 using TF - 9.1
and CBR - 10.0. The point of intersection on the thickness scale
shows a continuously reinforced pavement to be required. The chart
thickness is 7.45 inches which is rounded to 8 inches
D. Since the 8 -inch thickness value is greater than the minimum
requirement for Class I Roads and Streets from Table 1, it will
be used for design purposes.
E. Determine if the soil "pockets" having a CBR value of 2.0 will be
adequate for the design thickness. Enter Chart 1 with
TF - 9.1 and CBR - 2.0
The point of intersection shows that a thickness of 7.85 inches is
required. Since this value is less than the 8 -inch design thick-
neas, it will not be necessary to replace the soil.
- 20-
Y
Determination of Equivalent Flexible Pavements
Since it is necessary to compare a rigid pavement with a flexible
pavement structurally to determine the most economical design, it is necessary
to relate the traffic factors for rigid and flexible pavements as they are not
equal. ttTables 3, 4, and 5 were developed to facilitate converting the rigid
traffic'factor to the corresponding flexible traffic factor. In the development
of the'iables, the effect of passenger cars has been omitted since their effect
in the traffic factor equations is negligible. Interpolations can be made in the
tables because of the straight line form of the equations. It must be noted that
comparisons can be made only if the design periods and class of road are the same.
The application of determining structurally equivalent design of rigid
and flexible pavements is as follows:
1. The total average daily traffic, comprised of average
daily passenger cars, single units and multiple units,
projected to one-half of the design period must be
known.
2. The California Bearing Ratio (CBR) of .the roadbed soil
must be known.
3. Calculate the rigid traffic factor using pertinent
formula from Table 2.
4. Using the rigid traffic factor and the CBR determine
the pavement type and thickness for the appropriate'
class of road. i
5. From the determined rigid pavement thickness find the
maximum rigid traffic factor that the pavement thickness
can support in the following manner: From Chart 1 or 2,
as appropriate, pass a line through the maximum range for
the determined thickness (0.3 inch over the even inch) on
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the thickness scale, through the CBR value on the
soil support scale and read the maximum traffic factor
that the pavement thickness can support on the traffic
factor scale.
u
6. Determine the percent of multiple uni- `of the commercial
traffic.
7. From Table 3, 4, or 5, depending on the class of road,
convert the maximum rigid traffic factor that the rigid
pavement can support to the equivalent flexible traffic
factor.
8. From the "Manuallfor the Structural Design of Bituminous
Pavements in Illinois" the equivalent flexible pavement
structural number is determined based on the equivalent
flexible traffic factor determined in Step 7.
9. The equivalent flexible pavement is then designed from
the determined structural number.
22 _
A
K
Table 3
Class I
TRAFFIC FACTOR -RIGID
Table for converting Traffic. Factor -Rigid to Traffic Factor -Flexible for various
percentages of multiple units (MU)
Note: For converting TF -Rigid to TF•Flexible, the design periods must be equal
TFR 42.705(1-m) + 345.655m Where m MU
Chart based on equation TF
F MU + SU
44.895(1-m) + m -
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1
2
3
4
5
6
7
8
9
10
5-
0.9078
1.816
2.723
3.631
4.539
5.447 j
6,355
7.262
8.170
9.07
10
0.8842
1.768
2.653
3.537
4.421
5.305
6.189
7.074
7.958
8.84
15
0.8693
1.739
2.608
3.477
4.347
5.216
6.085
6.954
7.824
8.69
20
0.8591
1.718
2.577
3.436
4.296
5.155
6.014
6.873
7.732
8.59
25
0.8517
1.703
2.555
3.407
4.259
5.110
5.962
6.814
7.665
8.51
30
0.8461
1.692
2.538
3.384
4.231
5.077
5.923
6.769
7.615
8.46
35
0.8435
1.687
2.531
3.374
4.218
5.061
5.905
6.748
7.592
8.43
40
0.8380
1.676
2.514
3.352
4.190
5.028
5.866
6.704
7.542
8.38
45
0.8350
1.670
2.505
3.340
4.175
5.010
5.845
6.680
7.515
8.35
50
0.8322'
1.664
2.497
3.329
4.161
4.993
5.825
6.658
7.490
8.32
60
0.8286
1.657
2.486
3.314
4.143
4.972
5.800
6.629
7.457
8.28
70
0.8256
1.651
2.477
3.302
4.128
4.954
5.779
6.605
7.430
8.25
80
0.8231
1.646
2.469
3.292
4.116
4.939
5.762
6.585
7.408
8.23
Table for converting Traffic. Factor -Rigid to Traffic Factor -Flexible for various
percentages of multiple units (MU)
Note: For converting TF -Rigid to TF•Flexible, the design periods must be equal
TFR 42.705(1-m) + 345.655m Where m MU
Chart based on equation TF
F MU + SU
44.895(1-m) + m -
- 23-