The purpose of this chapter is to give the standards to which
all streets should be designed and built.
All streets shall conform to the applicable geometric, cross-section,
and intersection standards outlined in the Subdivision Regulations
and standard drawings, including the design criteria for right of
way width, design speed, pavement width, minimum and maximum grades,
horizontal and vertical sight distance, cross slope and sidewalk width.
Where design criteria are not specified in any locally adopted document,
the design standards contained in the AASHTO "Green Book" (A Policy
on the Geometric Design of Highways and Streets, 2011 version) shall
apply. All newly constructed streets in or adjacent to areas of special
flood hazard shall be constructed above the base flood elevation.
All embankments, excavation, grading, stripping, topsoiling,
etc., shall be done in accordance with the following specifications.
3.2.1.
GENERAL. Only materials acceptable to the Engineer shall be used
in embankment formation. No frozen material, stumps, logs, roots or
other perishable or organic materials shall be placed in any embankment.
No stone or masonry fragment greater than 4 inches in any dimension
shall be placed within 12 inches of the finished grade elevation.
All excavation, embankment construction, grading and topsoiling
shall be accomplished at such places as are indicated on the plans
and to the lines, grades and elevations shown on the plans, in the
specifications or as directed by the Engineer.
3.2.2.
EMBANKMENT CONSTRUCTION METHODS. Before embankment placement is begun,
all vegetation and rubbish shall be removed from the area within the
limits of the embankment. This material shall be disposed of in a
method approved by the Engineer.
Embankments shall not be constructed upon frozen areas. All
snow and ice shall be removed from the area to be covered prior to
placement of embankment material.
Earth embankment shall be formed by distributing the material
in successive uniform horizontal layers not exceeding 12 inches in
thickness, loose depth, to the full width of the cross section. Each
layer of the embankment shall be thoroughly compacted as hereinafter
specified. The embankment shall be properly drained at all times.
a.
Clearing and Grubbing. The developer shall accomplish all clearing
and grubbing within the limits designated on the plans or as directed
by the Engineer, or as required for the construction of the work involved
and shall satisfactorily dispose of all materials so removed.
The work under this paragraph shall consist of cutting and removing
all trees, stumps, brush, logs, removal of fences, or other loose
or projecting material within the designated areas. Unless otherwise
specified, it shall also include the grubbing of stumps, roots, and
other natural obstructions which, in the opinion of the Engineer,
must be removed to properly prosecute the construction work and properly
operate the facility upon completion of construction. Disposal shall
be by burning or other methods satisfactory to the Engineer. Trees
which are designated to remain shall be properly protected.
b.
Excavation. This work shall consist of the removal and satisfactory
disposal of all materials taken from between the original ground line
and the excavation limits approved by the Engineer as shown on the
final cross-sections.
All materials encountered, of whatever nature, within the limits
designated shall be removed and disposed of as directed. During the
process of excavation, the grade shall be maintained in such condition
that it will be well drained at all times. When directed, temporary
drains and/or drainage ditches shall be installed at the Developer's
expense to intercept or divert surface water which may affect the
prosecution or condition of the work. If at any time it is not possible
to place excavated material in its final location in the permanent
construction, it shall be stockpiled in approved areas for later use.
Where rock, shale, clay, hardpan or other unsatisfactory subgrade
material is encountered, it shall be excavated to a depth of at least
12 inches, or to such greater depth as the Engineer may direct. The
portion so excavated shall be refilled and compacted as set out herein
or as specified by the Engineer.
c.
Embankment Compaction. Place the soil layers to a uniform density
not less than 95 percent of maximum density as determined by the Method
of ASTM D1557 Modified Proctor.
Should the subgrade lose its density for any reason, it shall
be recompacted or replaced as directed by the Engineer. Any area in
the subgrade which has yielding or unsuitable material shall be excavated
and backfilled with approved material properly compacted as directed
by the Engineer.
Breakage and undercutting, including slides in that portion
of any material displaced or loosened beyond the limits of the finished
work, shall be removed by the developer and disposed of as directed
by the Engineer.
3.2.3.
Grading. Consists of the preparation, shaping, and compaction of
that portion of the roadbed upon which aggregate or pavement, including
shoulders is to be placed.
a.
Subgrade Preparation. Shape subgrade to the lines, grades and typical
sections shown on the plans. Where the Engineer directs that areas
of the subgrade are to be stabilized, the subgrade surface in such
areas shall be left uniformly below grade to provide for the addition
of stabilizer aggregate. Geotextile, filter fabric, or similar products
may also be installed if shown on the plans or required by the Engineer.
Material excavated in preparing the subgrade shall be stored
or stockpiled in such manner as to not interfere with proper drainage
or any of the subsequent operations of placing base or pavement.
Compaction of subgrade shall be accomplished as set out in the
section on "Embankments". The developer shall dry or add moisture
to the subgrade to achieve a uniformly compacted and acceptable subgrade
and to achieve the specified compaction at or near optimum moisture
content as determined by ASTM D 1557 Modified Proctor.
A tolerance of plus or minus 3/4 inch from the established grade
will be permitted in the graded, compacted subgrade. No base or pavement
construction shall begin on subgrade which has not been inspected
and approved by the Engineer.
b.
Subgrade Drainage. Perforated pipe underdrains shall be required
when subgrade conditions warrant, at the discretion of the Engineer.
Perforated pipe shall conform to the requirements of Section 704 of
the KYTC Standard Specifications. Pipe bedding and backfill shall
consist of No. 78, 8 or 9M Coarse aggregate. Perforated pipe shall
be a minimum of four inches (4") diameter. Minimum trench width shall
be eighteen inches (18"). Provide outlet headwalls or connections
to drainage structures conforming to KYTC requirements. See Exhibit
3-2.[1]
When backfilling, place geotextile fabric in the trench and
shape to the sides and bottom of the trench without stretching the
fabric. Ensure that the geotextile fabric does not pull down into
the trench when placing the backfill material. Do not damage the geotextile
fabric when placing the filter aggregate. Fold the fabric over the
backfilled trench and secure it with steel pins at intervals of 5
feet to produce a double thickness of fabric over the top of the trench.
[1]
Editor's Note: The Exhibits are included as an attachment to this chapter.
c.
Stabilized Shoulder. Where stabilized shoulder is required (rural-type
typical sections without curb and gutter) it shall consist of crushed
stone or dense graded aggregate courses equal in depth to the total
depth of the adjacent pavement section. Design details shall be as
specified by the Engineer, and shall consider traffic and zoning classification
of the area.
Base course shall be of Dense Graded Aggregate (DGA) as per
the KYTC Standard Specifications, and shall be a minimum of six (6)
inches thick after compaction for bituminous concrete pavements. Additional
DGA thickness may be required as shown on approved plans.
Number 610 crushed stone or crushed (recycled) concrete may
be used in lieu of DGA where permitted by the Engineer. Crushed concrete
used as base shall meet grading requirements set by the Engineer,
and shall be reasonably free from metal and other deleterious material.
The DGA shall be placed on the prepared subgrade, shaped and
compacted to the lines, grades and cross sections shown on the plans
or approved by the engineer. It shall have no more than plus or minus
1/2 inch deviation from the typical section after compaction. The
base material shall be placed in a manner that produces uniform grades
and cross sections satisfactory to the Engineer.
The DGA base shall be compacted to a density of not less than
90% of solid volume throughout the layer. The density determination
will be based on the oven-dry bulk specific gravity, ASTM C-127 and
the dry weight of the aggregate from the test hole. The in-place density
will be determined by the Method of Test for Density of Soil in place
by the Rubber-Balloon Method, ASTM D-2167.
All bituminous concrete shall be hot-mixed and hot-laid on a
prepared subgrade, old surface or underlying course. The pavement
on new construction shall consist of not less than:
Three (3) inches of KYTC Class 2 Asphalt Base, 0.38D PG64-22;
and
One (1) inch of KYTC Class 2 Asphalt Surface, 0.38D PG64-22.
3.4.1.
SPREADING AND FINISHING. All bituminous concrete shall be laid using
self-propelled pavers which are capable of spreading and screeding
all courses to the indicated widths and depths, true to line, grade
and cross section as shown on the plans or directed by the Engineer,
with a smooth finish uniform in density and texture. The screed shall
be preheated uniformly throughout its length. The paver shall be equipped
with hopper and distributing screws of the reversing type that will
place the material evenly in front of the screed. Mechanical or electronic
devices shall be provided to confine the edge to true line and to
adjust the gradeline so than minor changes in subgrade elevation will
not be reflected in the finished surface.
A string line shall be used for the first lane of each layer
of mixture placed to provide alignment control for the paver, except
that a string line will not be required when the first layer is placed
adjacent to a curb section.
Pavers shall be equipped with quick and efficient steering mechanism
and shall operate at variable speeds consistent with proper placement
of materials, but shall not exceed a speed of 50 feet per minute.
When placing adjacent lanes of the same course, pavers shall be equipped
with a joint matching device which will automatically provide control
of the depth of the mixture being placed so that, when compacted,
it will match the depth of the existing lane. All paving machines
shall be kept in first class mechanical condition.
All bituminous concrete shall be placed at a temperature of
not less than 225 degrees F and not more than 300 degrees F. After
screeding and before rolling, the surface of each course shall be
checked for irregularities and corrected as necessary. In areas where
machine paving is impractical, hand spreading is allowed. The material
shall be uniformly distributed, without segregation, to the depth
necessary to provide the required compacted depth. Rakes may be used,
but the final leveling and surface adjustment shall be done with mechanical
or manually operated screeds or lutes.
Where new bituminous pavement abuts old, an edge key or other
milling may be required by the Engineer to insure a smooth transition
between surfaces.
3.4.2.
COMPACTION. Roll each course as soon as the mixture has cooled sufficiently
to bear the weight of the roller without undue displacement. Each
paving operation shall have a minimum of the following rollers:
For initial or breakdown rolling on bituminous base course,
one tandem steel-wheeled roller weighing not less than ten (10) tons
and having a compressive capability at the rear wheels of at least
325 pounds per lineal inch of wheel width.
Provide intermediate rolling of at least 3 complete coverages
with a tandem roller weighing at least ten (10) tons. Pneumatic tired
rollers may be used when approved by the Engineer.
These rollers shall be in good condition, capable or reversing
without backlash. The steel-wheel rollers shall be equipped with wetting
devices to prevent the mixture from sticking to the roller wheels.
Perform final rolling of the uppermost layer or surface course
with a tandem roller. Operate the roller, at all times, parallel to
the centerline. Begin rolling at the sides and progress to the center
on crowned surfaces. Begin rolling at the low side and progress to
the high side on superelevated sections. Operate the rollers parallel
to the centerline, and lap successive trips of each roller uniformly
to the previous trip. End alternate trips of the rollers on transverse
lines at least 3 feet apart. Regulate starting and stopping of the
rollers to avoid distorting the surface.
In areas inaccessible to equipment, the mixture shall be thoroughly
compacted by the use of hand tampers or hand operated mechanical tampers.
3.4.3.
SURFACE TOLERANCE. Final surface shall show no deviation greater
than 1/4 inch from a ten (10) foot straight edge placed parallel to
the centerline of the street, nor more than 1/4 inch from the typical
cross-section.
3.4.4.
MINIMUM CONSTRUCTION LENGTH. Minimum construction length of street
which will be approved to receive bituminous paving shall be 500 feet
or the distance between street intersections unless otherwise approved
by the Engineer.
Except for streets stubbed out to adjacent property, the subgrade
shall be prepared to elevations as shown on the plans for a minimum
of 25 feet beyond the end of the base aggregate.
The bituminous base shall be placed no closer than 10 feet from
the end of an aggregate base and the bituminous surface no closer
than 5 feet from the end of the bituminous base.
3.4.5.
JOINTS. When the laying of the mixture is to be suspended long enough
to permit the mixture to become cool, cut back a distance of one foot
(1') or to full-depth asphalt, whichever is greater, to allow correct
tie-in to the cold joint. Such joints shall be vertical and in a straight
line perpendicular to the course.
At the end of the day construct a sloped wedge ahead of the
end of the full depth pavement to provide for proper compaction and
protection of the full depth pavement.
When multi-lane, multi-layer construction is required, the width
of paving spreads shall be adjusted so as to provide for off-setting
of longitudinal joints in the base and surface courses.
3.4.6.
Weather and seasonal limitations. No bituminous concrete shall be
laid when the air temperature is below 40 degrees F, nor when the
underlying course is wet, nor when other weather conditions are unsuitable.
No hot-mix bituminous concrete shall be laid between December
1 and April 1, without prior written approval by the Engineer.
Shall consist of a single course, having a minimum depth of
at least six (6) inches and shall be constructed on a prepared base
in close conformity with the lines, grades and cross-sections shown
on the plans, in accordance with the specifications contained herein.
DGA base shall not be required under cement concrete pavement
unless warranted by subgrade conditions as deemed necessary by the
Engineer. Number 610 crushed stone or crushed (recycled) concrete
may be used in lieu of DGA where permitted by the Engineer. Crushed
concrete used as base shall meet grading requirements set by the Engineer.
The pavement shall include longitudinal and transverse joints
as shown on the plans in accordance with the specifications contained
herein. The concrete pavement shall be at least six inches (6") thick
and shall consist of Type "P" 4000 psi, air entrained concrete in
accordance with the KYTC Standard Specifications.
Perforated pipe underdrains shall be installed parallel to the
centerline of the street as shown on the plans in accordance with
these specifications.
3.5.1.
PREPARATION AND CONTROL OF CONCRETE MIXES. Shall be made in accordance
with the following specifications and shall meet the approval of the
Engineer.
a.
Batching may be performed at a batch plant, central mix plant, or
in truck mixers as approved by the Engineer. All such plants or mixers
shall have bins, weighing hoppers, and scales which meet the approval
of the Engineer.
b.
Proportioning. The Engineer shall approve the proportions for the
aggregates and water to obtain a satisfactory mix with the required
cement content, and no subsequent changes will be permitted except
as directed by the Engineer. The concrete mix shall be designed to
a six (6) bag mix of cement for each cubic yard produced.
The quantity of fine aggregate shall not be less than 35% nor
more than 38% of the total combined solid volumes of the fine and
coarse aggregate in a saturated surface dry condition, used in the
proportions per bag of cement. The aggregates shall be proportioned
to use the maximum percentage of coarse aggregate and the minimum
percentage of fine aggregate which will produce a plastic workable
mix. When the aggregates are drier than a saturated-surface-dry condition,
or when the aggregates contain free moisture, proper adjustments shall
be made for aggregate batch weights to compensate for any such conditions.
The maximum free water content in the mix, including the surface
moisture in the aggregates, shall not exceed 5.75 gallons per bag
of cement.
c.
Consistency of Concrete. The mixture shall contain no more water
than is necessary to produce a workable plastic concrete. The consistency
of the concrete shall be continuously uniform and shall be measured
in accordance with the "Slump Test" ASTM C-143.
The slump shall not be less than 1-1/2 inches nor more than
2 inches for concrete to be placed without vibration. The slump shall
not be more than 1-1/2 inches when the concrete is to be vibrated
during placement.
d.
Air Entrainment. Unless otherwise specified, the required air content
of the concrete shall be 6, plus or minus 2, percent by volume. The
entrainment of air shall be accomplished by approved methods.
e.
Strength of Concrete. The minimum strength of concrete pavements
at 28 days shall be 4,000 pounds per square inch compressive strength
and 500 pounds per square inch modulus of rupture when tested in accordance
with methods ASTM C-39 and ASTM C-78, respectively. The Engineer may
direct the removal and replacement of sections of the pavement from
which the concrete specimens consistently test at low strength. Obtain
sample of fresh concrete in accordance with ASTM C-172. Test cylinders
for all classes of concrete shall be taken in sets of two, six inch
diameter by twelve inch height (6" x 12") cylinders from a composite
sample of concrete placed. Cylinders are tested and the average is
treated as a single test. Developer shall pay the costs of all applicable
testing.
f.
Hauling Equipment. The concrete shall be transported in truck mixers
approved by the Engineer.
g.
Weather Limitations. Conform to limitations on maximum and minimum
mixture and ambient temperatures as per the KYTC Standard Specifications.
3.5.2.
SUBGRADE AND BASE PREPARATION. Subgrade for Portland cement concrete
pavement shall be constructed in accordance with the requirements
of Section 3.2.3(a) using an approved machine to produce final subgrade
and base surfaces meeting the lines, grades and cross-sections required
by the plans.
The surface of the base shall be damp at the time the concrete
is placed. The developer shall satisfactorily correct all soft areas
in the subgrade or base prior to placing concrete.
Proper protection measures should be taken to prevent disturbance
to the subgrade due to hauling over subgrade.
Subgrade underdrains conforming to the requirements of Section
3.2.3 above may be required as directed by the Engineer.
3.5.3.
FORMING. Forms shall be of such section and design that they will
adequately support the concrete and the construction equipment.
All forms shall be inspected and approved by the Engineer or
his authorized representative, prior to placement of concrete. Forms
shall be straight, free from warp, smooth faced, and of sufficient
strength to support the concrete during construction.
The top face of the form shall not vary from a true plane more
than 1/8 inch in ten feet. All forms shall be thoroughly oiled before
any concrete is placed. Forms shall be set a sufficient distance in
advance of the point where the concrete is being placed to provide
for a continuous operation in placing the concrete and for proper
inspection of line and grade.
Forms shall not be removed from freshly placed concrete until
it has hardened sufficiently to resist spalling, cracking or any other
damage, but in no case until at least 12 hours after the concrete
has been placed. Any honey-combed areas along the sides or edges of
the slab shall be repaired by filling with mortar immediately after
the forms have been removed. The mortar shall consist of one part
cement and two parts fine aggregate.
3.5.4.
CONCRETE PLACEMENT. Concrete shall be handled in such a manner as
to prevent segregation and kept free from mud, soil or any other foreign
matter.
Paving operations shall not be undertaken or shall be discontinued
when any of the following conditions exist:
a.
When a descending air temperature in the shade and away from artificial
heat reaches 40 degrees F.
b.
When the subgrade or base course is frozen.
c.
When aggregates to be used in the mix contain frozen particles.
The mixer and hauling equipment shall not be operated on any
new pavement until at least 10 curing days have elapsed. When the
mixer is operated on new pavement, the developer shall utilize wood
matting or other approved material which will prevent the marking
of the pavement and will distribute the load uniformly over the area.
3.5.5.
SPECIAL DESIGN. Special designs may be required by the Engineer if
subsoil condition is not adequate for heavily traveled and industrial
roads.
3.5.6.
SPREADING AND VIBRATING CONCRETE. The concrete shall be spread over
the entire area between the forms without segregation. Spreading shall
be done with appropriate spreading equipment. After the concrete has
been placed, it shall be uniformly vibrated. This vibrating shall
be accomplished by approved methods.
3.5.7.
CONCRETE FINISHING. Finish concrete with approved equipment. Hand
finishing will be permitted when the use of mechanical finishing equipment
is impractical. The concrete shall be screeded and float finished
to the required cross-section and then shall be checked by the use
of hand-held, 10 foot straightedges for longitudinal surface uniformity.
The final finishing of the pavement shall be accomplished by burlap
dragging, brooming or other acceptable methods which produce a similar
surface texture. Finish the outside edges and edges of expansion joints
with an edging tool having a radius of 1/8 inch.
3.5.8.
JOINTS.
Shall be constructed according to the plans. Joint details shall follow
the requirements of the KYTC Standard Specifications and Standard
Drawings, with the exception that deformed tie bars shall be required
only on transverse joints on collector and arterial streets.
a.
Transverse
Contraction Joints. Shall be formed by an approved joint tool or by
sawing with an approved concrete saw.
Where transverse contraction joints are to be sawed, approved
joint filler shall be placed at intervals to control random cracking.
Sawing shall be done as soon as the concrete has hardened sufficiently
to be sawed without spalling and raveling, usually 6 to 24 hours after
placing and before shrinkage cracking occurs.
Transverse contraction joints shall be constructed at 20 foot
intervals unless otherwise shown on the plans. Where the pavement
is constructed adjacent to an existing concrete pavement, joints shall
be placed to match the existing joints.
b.
Longitudinal
Contraction Joints. Shall be constructed in all pavements wider than
20 feet in accordance with the details and dimensions shown on the
plans, and shall be formed by an approved joint insert or by an approved
concrete saw.
When a joint insert is used, the alignment of the finished joint
shall be parallel with the center line of the pavement and shall be
free from local irregularities in alignment.
Where longitudinal contraction joints are sawed, sawing shall
be done as soon as the concrete has hardened sufficiently to be sawed
without spalling and raveling, but not more than two (2) days after
the concrete is placed.
c.
Transverse
Construction Joints. Shall be constructed at the end of each day's
operation (planned joint) or whenever the placing of concrete is suspended
for more than 30 minutes (emergency joint). The joints shall be formed
by placing an approved header shaped to fit the pavement typical section
which forms a vertical face on the end of the pavement, and perpendicular
to the pavement section.
Reinforcing steel tie bars shall be required at transverse construction
joints on collector streets and arterials, and shall be epoxy coated.
The header shall be designed to permit the placement of tie or dowel
bars, where required, and shall hold such bars in their correct locations,
in accordance with the joint detail drawings contained in the approved
plans.
Planned transverse construction joints shall be located at the
same spacing required for transverse contraction joints.
The spacing of contraction joints shall not be changed due to
emergency construction joints and the emergency construction joint
shall not be located within three (3) feet of a contraction joint.
d.
Longitudinal
Construction Joints. Where necessary, shall be constructed in accordance
with the joint detail drawings contained in the approved plans.
e.
Transverse
Expansion Joints. Shall be constructed in accordance with the joint
detail drawings contained in the approved plans.
f.
Sealing
of Joints. The concrete shall be at least three (3) days old before
the joint is sealed. Joints shall be sealed as soon after this three
day period as possible, and before any traffic is allowed on the pavement.
The joint shall be thoroughly cleaned and dry before sealing.
When the joints have dried, they shall be filled to within approximately
1/8 inch of the surface of the pavement with joint sealer. Care shall
be taken in handling the nozzle of the application equipment so that
the joint will be filled from the bottom up. Any sealer spilled on
the surface of the concrete shall be removed immediately.
A pre-molded insert may be used to seal joints where shown on
the plans.
3.5.9.
CURING CONCRETE. Immediately after finishing operations have been
completed and surface water has disappeared, all exposed surfaces
of the pavement shall be cured by one of the following methods.
The total curing period shall be a minimum of three (3) days
for all methods.
a.
Liquid Membrane Curing Compounds. The minimum rate of application
shall be one (1) gallon per 200 square feet when the application equipment
is mechanically operated or one (1) gallon per 150 square feet when
the application equipment is hand operated.
b.
Polyethylene Film. The sections of the film shall be spread in such
a manner which will prevent damage to the finished pavement surface.
Lap joints of the sections will be at least 12 inches wide and suitable
precaution shall be taken to prevent the circulation of air beneath
the film.
c.
Burlap. The sections of the burlap shall be spread in such a manner
which will prevent damage to the finished pavement surface. Lap joints
will be at least 6 inches wide.
The burlap shall be thoroughly saturated prior to placing on
the concrete and shall be kept thoroughly wet throughout the curing
period.
3.5.10.
PROTECTION FROM COLD WEATHER AND RAIN. Concrete less than 72
hours old, which may be subject to damage by freezing, shall be adequately
protected by insulation or heating until the concrete reaches an age
of 72 hours. Concrete damaged as a result of freezing shall be removed
and replaced at the expense of the developer.
Protective coverings which will protect the surface of freshly
placed pavement from rain shall be readily available at the site of
the work. An adequate quantity of other materials shall be stored
at the paving train. Concrete damaged as a result of failure on the
part of the developer to adequately protect the concrete from rain
shall be repaired or removed and replaced at the expense of the developer.
3.5.11.
FINAL SURFACE TESTING. As soon as the concrete has set sufficiently
to permit walking on it without marring the surface, it shall be tested
by the contractor in the presence of the Engineer along the center
point and the quarter points of the pavement with a rolling straightedge
furnished by the contractor.
The rolling straightedge (profilograph) shall be 10 feet in
length between the centers of the wheels. It shall be so designed,
constructed and adjusted so that it will adequately indicate and mark
all pavement areas which deviate from a plan surface by more than
1/4 inch in 10 feet. The rolling straightedge shall be of a design
approved by the engineer.
All deviations more than 1/4 inch in 10 feet marked by the straightedge
shall be corrected to within this tolerance by being rubbed or ground
down and refinished, or shall be replaced if directed by the Engineer.
