HomeMy WebLinkAbout94-96 RESOLUTIONRESOLUTION NO. 94-96
A RESOLUTION APPROVING THE PROPOPSED REVISIONS
TO THE MINIMUM STREET STANDARDS.
BE IT RESOLVED BY THE CITY COUNCIL OF THE CITY OF
FAYETTEVILLE, ARKANSAS:
Section 1. That the City Council hereby approves the revisions proposed to the
Minimum Street Standards. A copy of the street standards are attached hereto marked Exhibit
• "A" and made a part hereof.
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PASSED AND APPROVED this 6th day of August , 1996.
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Traci Paul, City Clerk
APPROVED:
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ed Hanna, Mayor
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TABLE OF CONTENTS
ITEMS PAGE NO.
APPROVAL RESOLUTION i
SECTION 1, GENERAL REQUIREMENTS:
1. Requirement to Extend Streets 1
2. City Participation in Street Extension Costs 1
3. Required Street Right of Way 2
4. Permits 3
5. Approval of Plans and Specifications 3
6. Responsibilities of Owner/Developer 3
7. Engineering Services 4
8. Plan Submittal 5
9. Observation of Construction City 5
10. Acceptance by the City 5
11. Maintenance Warranty 6
12. Definitions 6
13. Need for Traffic Study 7
14. Subdivision Signs and Ornamental Structures 8
15. Sidewalks and/or Trails 8
16. Applicability 9
SECTION 2, DESIGN DATA AND PLAN SUBMISSION
1. General 1
2. Design Report 1
3. Horizontal and Vertical Datum 1
4. Plans 1
5. Specifications 2
6. As -Built Plans 3
SECTION 3, STREET DESIGN PRINCIPLES
1. General 1
2. Alignment 1
3. Intersections 1
4. Cross Sections and Right of Way Widths 2
5. Railroad Crossings 2
6. Minimum and Maximum Grades 3
7. Sight Distance Requirements and Design Speeds 3
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SECTION 4. PAVEMENT DESIGN
1. Pavement Types 1
2. Pavement Materials and Construction 1
3. Subgrade Material 1
4. Base Course 3
5. Surface Course 3
6. Curb and Gutter 3
7. Subsurface Drainage 3
8. Pavement Section Design Requirements 4
a) Geotechnical 4
b) Sampling and Testing 4
c) Soil Classification 5
d) Load Bearing Strength 5
SECTION 5, UTILITIES AND UTILITY CROSSINGS 1
SECTION 6, EROSION CONTROL
1. Requirement for Erosion Control 1
2. Permits Required 1
3. Permanent Erosion Control Measures 1
SECTION 7, INSPECTIONS AND TESTING
1. General 1
2. Inspections 1
3. Quality Control Testing 2
4. Construction Inspection Checklist 2
5. Additional Tests and Testing Frequency 4
APPENDIX "A", PAVEMENT DESIGN CRITERIA
APPENDIX "B", TYPICAL PAVEMENT DESIGNS
APPENDIX "C", ACKNOWLEDGEMENT LETTER FORM
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MINIMUM STREET STANDARDS
SECTION 1, GENERAL REQUIREMENTS
1-1 Requirement to Extend Streets:
Authority to require, street extensions and improvements are
included in the Subdivision Regulations of the City of Fayetteville
as interpreted by the City Staff and the Planning Commission of the
City of Fayetteville; and in the Master Street Plan as approved by
the City Planning Commission and as adopted by the Fayetteville
City Council.
All of the rules, regulations, and Standards contained herein
are promulgated under the authority given the City Engineer and
Planning Department of the City and are intended to conform to
above listed authorities.
All new development of any kind shall be required to extend,
at the expense of the Owner/Developer, streets within the
development in accordance with these standards and in accordance
with applicable ordinances and other rules and regulations
governing the extension of streets.
Streets adjacent to and leading to such developments may also
be required to be constructed or otherwise upgraded, at the expense
of the Owner/Developer, to meet the intent of these Standards.
Streets within developments shall be extended to the edge of
the property boundaries where required either to conform to the
Master Street Plan or to provide for the general circulation of
traffic within the neighborhood. Such extensions to property
boundaries shall be fully constructed complete with curb and gutter
and drainage. A temporary cul-de-sac may be required on such
streets and, depending on the timing of any extension, a permanent
cul-de-sac may be required.
1-2 City Participation in Street Extension Costs:
The City may participate in the construction of streets either
adjacent to a Development or on a street leading to a development
if the need for such improvement is not totally caused by the
Development in question. The appropriateness of any such cost
sharing between the Owner/Developer and the City shall be
determined by the Planning Commission based on City Ordinances
governing the cost sharing of streets.
In no case shall the City participate in Local or Residential
streets within Developments.
1- 1
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Where streets classified as Collector or higher are required
to be constructed as part of a Development, the Owner/Developer
shall be financially responsible for their share of the cost of the
higher classified street. The developer's share shall be that cost
which bears a rational nexus to the needs created by the
development. In no case shall the developer be responsible for less
than the cost of a standard 31 foot local street. In all cases,
regardless of the developer's cost share, the Owner/Developer shall
be responsible for the granting of all street right of way required
by the higher street classification
City participation in any cost sharing project shall be depend
on the availability of funds.
1-3 Required Street Right of Way:
Street right of ways in connection with required street
extensions and improvements shall be granted to the City by the
Owner/Developer either by virtue of a Final Plat or Easement Plat
filed at the County Court House or by a separate instrument. Such
rights of way shall be controlled by the City and shall be utilized
by the City for all purposes allowed by City and State law,
including, but not limited to the construction of streets,
extension and replacement of utility lines, drainage facilities,
and all related appurtenances, and by private utility companies and
TCA Cable for the placement and replacement of their lines.
Additional rights of way may be required in certain instances
where no street construction or improvements are anticipated either
for the eventual extension or improvement of the street or to bring
the existing right of way width into conformance with the Master
Street Plan.
Rights of way and pavement widths shall be as called for in
the City's Master Street Plan as adopted or as may be amended from
time to time. It is understood that the widths listed in the Master
Street Plan are minimum widths only. Additional right of way may be
required where the need for wider rights of way is dictated by the
topography or other feature of the property.
1- 2
1-4 Permits:
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All permits required to accomplish the work shall be the
responsibility of the Developer/Owner or the Engineer of Record.
Such permits may include but are not limited to permits for work
within Highway Department R/W, railroad crossing permits, "Notice
of Intent" for Erosion Control (ADPC&E), a Stormwater Construction
Permit, and a Grading Permit.
1-5 Plans and Specifications:
Detailed Plans and Specifications shall be required for all
new streets and street extensions and shall be prepared by a
Professional Engineer registered to do business in the State of
Arkansas.
The Standard Specifications for HIGHWAY CONSTRUCTION as
promulgated by the Arkansas State Highway and Transportation
Department, Edition of 1993 , and the STANDARD DRAWINGS of the
Arkansas Highway Department (11-11-92) shall be the basis for the
preparation of the Detailed Plans and Specifications and shall
apply in all cases except where these Standards are in direct
conflict with them.
Approval of the Detailed Plans and Specifications by the City
of Fayetteville does not constitute a warranty of the Plans and
Specifications and does not relieve the Engineer of Record of his
professional responsibility in the design of the facilities or in
the preparation of any engineering reports done in association with
the project.
1-6 Responsibilities of Developer/Owner
The Developer/Owner shall be responsible for installation of
streets, including all design and construction, and for all costs
associated therewith except in situations where cost sharing may be
appropriate as described in Section 1-2 (City Participation in
Street Extension Costs).
All formal agreements entered into by the City will be with
the Developer/Owner only. Such agreements will bind each principal
of the Developer/Owner regardless of the Developer/Owner's form of
organization.
The Developer/Owner shall provide all engineering services
required for planning, design, investigations, inspection, testing,
and related activities necessary for street development, and shall
be responsible for construction of street improvements in
accordance with the design approved by the City as satisfying the
requirements of these standards.
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The Developer shall post a letter which 1) guarantees that the
construction will conform to the plans and specifications approved
by the City, 2) acknowledges the conditions of the approval, and 3)
agrees to honor those conditions. This letter must be posted prior
to the beginning of construction and shall be of the form shown in
Appendix "C".
The Developer/Owner is hereby required to have contained
within the construction contract he executes with his Contractor a
requirement to obtain a Performance and Payment Bond for the entire
contract amount. The Developer/Owner shall assign said Performance
and Payment Bond to the City in a form approved by the City
Attorney. The Bond shall be issued by a company licensed to do
business in the State of Arkansas.
The Developer/Owner may, in lieu of assignment of the
Performance and Payment Bond to the City, post a cash deposit or an
irrevocable Letter of Credit with the City in the full amount of
the proposed improvements. If a Letter of Credit is issued as
assurance of construction, the City shall have the right of
approval of the financial institution involved and the terms of the
Letter of Credit.
The amount of security shall be the total estimated
construction cost associated with the street construction. That
amount may not be diminished or drawn down during construction. The
total shall remain intact until the job has been accepted.
The City shall have the right of access to sites during the
planning, design, and construction phases of street development.
The Developer shall schedule all activities to provide the City
with adequate notice and review time.
The Developer shall provide a Two (2) year Maintenance Bond to
the City as specified in Section I-11 of these Standards.
1-7 Engineering Services:
All engineering services, including but not limited to,
planning, design, investigations, inspection, and testing shall be
under the supervision of a Professional Engineer registered in the
State of Arkansas (Engineer of Record).
The design data, plans, specifications, and related
information shall bear the name of the Engineer of Record. The
registration seal of the Engineer of Record shall be placed on each
sheet of the Plans along with his/her signature.
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Soils investigations, materials testing, and quality control
testing shall be performed by a laboratory approved by the City
Engineer. All reports submitted shall bear the name of the Engineer
of Record.
Certification by the Engineer of Record that materials and
construction conform to the approved Plans and Specifications is
required. Inspection and testing requirements are outlined in
Section 7 of these Standards.
1-8 Plan Submittal:
Plans, Specifications, and all data submitted in conjunction
with the plans and specifications shall constitute a complete
design. Approval by the City will not be issued until all
requirements have been fulfilled. Approval of the Plans and
Specifications shall remain in effect for one (1) year from the
approval date. After that time a new set of Plans and
Specifications must be submitted and any regulations or rules
promulgated between the time of the original submittal and the new
submittal date must be followed.
All significant changes in the design or construction of a
project or development, including all significant changes in the
Plans and/or Specifications, shall be submitted to the City for
approval. The City shall be notified immediately of all significant
field changes in order that a timely approval may be issued.
1-9 Observation of Construction by the City:
The observation of street construction by the City will be
limited to general observations of the project at various stages as
outlined in Section 7 of the Standards. The City reserves the right
to observe the construction at all times.
1-10 Acceptance By The City:
After the Final Inspection and Acceptable Completion of the
street construction, the Developer/Owner shall provide a
Maintenance Warranty to the City which guarantees the maintenance,
repair, and/or reconstruction of the project in whole or in part
for a period of 24 months after the date the Maintenance Warranty.
The Maintenance Warranty shall be in the amount of 100 percent of
the cost of construction of the improvements.
Formal Acceptance of the project by the City will be made in
writing after the posting of the Maintenance Warranty. The date of
formal acceptance shall be the same date as given in the
Maintenance Warranty.
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1-11 Maintenance Warranty:
The Maintenance Warranty may be either:
a) A formal Maintenance Bond issued by a company
licensed to do business in the State of Arkansas.
The bond shall be for a two year period, said
period beginning with the date on the bond.
b) An extension of the Performance and Payment Bond
for the full two (2) year warranty period provided
all parties acknowledge and agree to accept the
extension and assignment.
c) A cash deposit or letter of credit to satisfy
the maintenance warranty requirements.
Regardless of the type of Maintenance Warranty selected the
terms, conditions, form, and content must be approved by the City
Attorney. Generally, the Maintenance Warranty must state the
specific project involved, the warranty amount, how and under what
conditions the City has the right to draw upon that Maintenance
Warranty.
1-12 Definitions:
Whenever the following terms, abbreviations, or acronyms are
used in these specifications the intent and meaning shall be
interpreted as follows:
a) CITY - The City of Fayetteville, Arkansas, and its
employees expressly authorized by the Mayor to accomplish the
specified task.
b) DEVELOPER/OWNER - The person, firm, partnership,
corporation or other entity planning, constructing, altering
or reconstructing a public street.
c) ENGINEER OF RECORD - The Arkansas Registered Professional
Engineer responsible for the design of the improvements,
usually engaged by the Developer/Owner.
d) AASHTO - American Association of State Highway and
Transportation Officials.
e) AHTD Arkansas State Highway and Transportation Department.
f) ASTM - American Society for Testing and Materials.
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g) CONTRACTOR - The licensed contracting company hired by the
Developer/Owner to construct the street improvements.
h) ACCEPTABLE COMPLETION - This term shall mean substantial
completion of the street construction as agreed upon by the
CITY and the ENGINEER OF RECORD.
i) FORMAL ACCEPTANCE - Acceptance of the street construction
in writing after a Maintenance Warranty has been submitted to
and approved by the CITY.
j) STREET CONSTRUCTION - Where this or similar terms are used,
it shall mean construction of the street, curb and gutter,
drainage (whether on the street or not), and all other
appurtenances normally associated with street construction and
approved as part of the street plans, whether on site or off-
site.
k) FINAL INSPECTION - The final inspection shall be the formal
inspection of the street construction by the CITY, the
ENGINEER OF RECORD, and the CONTRACTOR which results in a
declaration of acceptable completion.
1) MAINTENANCE WARRANTY - The security instrument which binds
the Owner/Developer to a two (2) year responsibility for
street construction repairs and/or reconstruction in the event
of street construction failure.
m) USGS - United States Geological survey.
n) CBR - California Bearing Ratio.
o) ESAL - Equivalent Single Axle Load
p) SIDEWALK - Where the term sidewalk is used, it shall mean
either a sidewalk or trail as defined .in the Master Street
Plan.
1-13 Need for Traffic Study:
A formal Traffic Study may be required in connection with a
development if, in the opinion of the City Engineer and/or Planning
Director, it is required to properly determine future street
loadings and\or to determine cost shares between the City and the
Owner/Developer. A Traffic Study may also be required as a
condition of development by the Planning Commission.
1- 7
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1-14 Subdivision Signs and Ornamental Structures:
Subdivision signs proposed for installation by the
Developer/Owner for the benefit of his development shall be shown
on the Plans and be sized and located to meet the provisions of the
City's Sign Ordinance.
The location and size of all ornamental structures constructed
by the Developer/Owner shall be approved by the City's Traffic
Superintendent and by the City Engineer. In addition, the need to
conform to zoning regulations shall be determined by the Planning
Department. Generally, all structures over 30 inches high must meet
applicable setback requirements.
Where a subdivision sign or ornamental structure is proposed
to be located on City right of way, the exact location and size
shall be approved by the Planning Commission. The maintenance of
such signs and structures shall be by a properly established
property owner's association and provision for maintenance shall be
included in the covenants of the subdivision.
Any relocation of such signs and structures necessitated by
street widening, utility installation, or any other authorized use
of the right of way shall be the financial responsibility of the
property owner's association and shall be done at the call of the
City.
All permanent street and traffic signs shall be furnished and
installed by the City at no cost to the Developer/Owner.
1-15 Sidewalks and/or Trails:
Sidewalks and/or trails, where required shall be engineered
and shown as part of the street plans and specifications to be
approved by the City Engineer. The sidewalks and/or trails shall
then be constructed as part of the development improvements as
required by City Ordinance.
The necessary grading and subgrade preparation for sidewalks
and/or trails shall be done as part of the street construction even
if the installation of the actual sidewalks and/or trails are
delayed. Sidewalks and/or trails are required in accordance with
the City's Master Street Plan as adopted or as may be amended from
time to time.
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The construction of sidewalks and trails shall be in
accordance with the specifications on sidewalk and trail
construction as developed by the City as a separate document. The
construction shall adhere to these general principles:
a) Sidewalks shall be continuous through driveways with a cold
joint or expansion joint at the edge of the sidewalk opposite
the street.
b) The sidewalk edge adjacent to the street shall have at
least a grooved joint mark to clearly define the sidewalk
through the driveway.
c) The sidewalk elevation shall be two percent above the top
of the curb, sloping two percent towards the curb. This
elevation shall be continuous through the driveway.
d) The area remaining between the sidewalk and the flowline of
the gutter, called the approach to the driveway, shall slope
up to the elevation of the sidewalk.
e) Wood shall not be acceptable in sidewalks for expansion
joints. The joint material shall be the same as approved for
street construction purposes.
1-16 Applicability:
The regulations and requirements contained in these Street
Standards shall be applicable to all land or parcels of land being
developed for commercial, industrial, or residential use.
Where private streets are constructed either under the Planned
Unit Development section of the Zoning Ordinance or otherwise
approved by the City, the subbase, base, and paving shall meet the
applicable requirements of these Minimum Street Standards.
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MINIMUM STREET STANDARDS
SECTION 2, DESIGN DATA AND PLAN SUBMISSION
2-1 General:
The submittal shall be complete with all necessary information
included for review of the project. The material required shall
include, but shall not be limited to the Design Report, the Plans,
the Specifications, and the Drainage Report. No review based on a
partial submittal will be made. The final review will be concurrent
with the review of all public improvements, including water, sewer,
drainage, and final tree preservation.
2-2 Design Report:
The Design Report shall be a separately bound document and
shall contain all information not normally shown on the plans or
given in the specifications, including design calculations, results
of soil borings, soil test results, and any other design data used
in the development of the Plans and Specifications.
2-3 Horizontal and Vertical Datum:
All elevations shall be based on the USGS Survey and all
horizontal controls shall tie to the State Plane Coordinate System.
Both vertical and horizontal controls shall be tied to monuments as
described in the City's GPS Survey Report.
2-4 Plans:
The Plans shall be submitted on 24" X 36" sheets. No other
size will be allowed unless specifically approved by the City.
Plans shall be submitted at the scale necessary to make the
plans easily read and interpreted. Plans shall be on a scale of not
less than 1 inch = 50 feet. The layout shall include, but shall not
be limited to the following information.
1) Street right of way, proposed and existing
2) Existing and proposed utility easements
3) Curve Data
4) Stationing
5) Location and size of existing and proposed
utilities
6) Location and size of existing and proposed drainage
facilities
7) Intersection Radii
8) Soil Boring Locations
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9) California Bearing Ratio (CBR) Test Locations
10) Elevations at the beginning, mid -point, and end of
the radius returns at all intersections
11) A legend showing typical symbols used in the plans
12) Existing and proposed property lines
13) North arrow
14) Street and Right of Way dimensions
15) Sidewalks and trails
Street profiles shall be shown on a horizontal scale to match
the layout with a vertical scale of not less than 1 inch = 5 feet.
Information to be shown with the profiles shall include, but shall
not be limited to:
1) Existing ground elevations
2) Proposed top of curb grades on each side of the
street
3) Vertical Curve Data
4) Proposed and existing drainage and utility line
crossings (size and location)
5) Proposed finished grades
6) Cross sections at a maximum spacing of 50 feet.
Additional cross sections shall be where needed for
clarification purposes
7) Sidewalks and trails
A typical street section shall be included in the Plans and
shall show the following:
1) Pavement type, width and thickness
2) Cross slope and crown
3) Location of profile grade
4) Curbs
5) Existing and proposed grades
6) Right of way width
7) Sidewalks or trails, if required
8) Landscaping, if required
Revisions to drawings shall be indicated above the title block
and shall show the nature of the revisions and the date made.
2-5 Specifications:
Technical specifications shall include material requirements
and methods of construction, quality control requirements,
sampling, and testing procedures and frequency as delineated in
other sections of these standards.
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2-6 As -Built Plans:
"As -Built" plans shall depict an accurate account of the
construction. Construction plans which are "rubber stamped" and
submitted for the purposes of "As -Built" Plans are not acceptable.
One set of "As -Built" Plans shall be required along with the
final costs associated with the Street Construction, and shall be
due prior to the filing of the Final Plat.
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MINIMUM STREET STANDARDS
SECTION 3, STREET DESIGN PRINCIPLES
3-1 General:
The principles governing the design of streets shall conform
to the requirements of these standards, to the standards that may
be referenced herein, and to appropriate City Ordinances.
General criteria with regard to street classification and
other characteristics shall be as stated in other sections of these
standards.
Parking, parking lots, driveways, stormwater drainage, and
erosion control requirements are specified in separate ordinances
and are not included in these standards.
3-2 Alignment:
Horizontal curves shall be circular curves with a minimum
centerline radii of not less than 150 feet for residential streets
and 200 feet for collector streets. Curves on streets with higher
classifications shall be designed on an individual basis. A tangent
of at least 100 feet shall separate reverse curves.
All vertical curves shall be parabolic type curves. Minimum
vertical curve lengths (L) shall depend on the design speed and
shall be equal to K times A where K equals the coefficient as shown
in the table below, and A equals the algebraic difference in grades
when the grades are expressed as a percentage.
Vertical Curve Coefficient (K)
3-3 Intersections:
Speed K Values
(mph) Crest Saq
25 20 30
30 30 40
35 40-50 50
Intersections shall be planned and designed to provide a safe
system for present and prospective traffic. Intersections shall be
graded to provide positive drainage and shall conform to the
alignment and grading requirements of these standards.
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The following standards shall
Design Consideration
Approach speed
Sight Distance (Minimum)
Grade Within 100 feet
Minimum Angle
Minimum Curb Radius
Local Streets
Collector Streets
Minimum Jogs
Local Streets
Collector Streets
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apply to intersection
Ordinary
25 mph
90 feet
0 %
75°
30 feet
50 feet
150 feet
200 feet
design:
It is understood that the sight distances
minimum and that longer sight distances may
topography will allow and/or when streets with
collector or higher are involved.
3-4 Cross Sections and Right of Way Widths:
Hilly
20 mph
70 feet
4 %
750
30 feet
50 feet
150 feet
200 feet
listed above are a
be required where
a classification of
Pavement cross sections shall conform to the details included
in these standards and are included in Appendix "D". Skewed street
sections will not be allowed without specific approval of the City
Engineer.
Pavement cross slopes for all streets shall be a minimum of 2
percent with a minimum crown height of 6 inches. Gutters shall be
sloped to match the street.
On the elevated side of a uniform cross slope or superelevated
street, the gutter may slope toward the street centerline provided
the gutter cross slope does not exceed the cross slope of the
adjacent lane. Transitions from normal crowns to uniform cross
slope or superelevated sections shall provide for minimum
longitudinal grades. Superelevated sections shall conform to the
AHTD Standard Drawings.
The minimum right of way shall be as called for in Section I-
3. Greater widths may be required if needed to accommodate a
particular street design.
3-5 Railroad Crossings:
Grade crossings at railroads shall provide for the same
minimum sight distances as street intersections. The ENGINEER OF
RECORD shall be responsible for all coordination with the railroad
company connected with approval of the crossing and shall work with
the City in obtaining a Joint Use Agreement with the railroad.
3-2
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3-6 Minimum and Maximum Grades:
The minimum grades shall be that grade required to provide
positive drainage for the street. The maximum allowable grade for
local streets shall be 10 percent with a provision for a 15 percent
grade for a maximum distance of 300 feet in the case of hilly
terrain. For collector streets the maximum grade shall be 8 percent
with a provision for 12 percent maximum grade for no more than 300
feet.
3-7 Sight Distance Requirements and Design Speeds:
Minimum sight distance for local and residential streets shall
be 250 feet under ordinary conditions and 200 feet for hilly
conditions. Collector streets shall have a minimum sight distance
of 150-350 feet, depending on the topography. The Arkansas Highway
and Transportation Department definition of site distance shall
apply. The design speed shall be 20 to 30 mph for local streets and
25 to 35 mph for collector streets.
3-3
4-1 Pavement Types:
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MINIMUM STREET STANDARDS
SECTION 4, PAVEMENT DESIGN
Street pavement sections shall be either flexible type with
an asphalt concrete surface or rigid type consisting of a
portland cement concrete section and surface. Curb and gutter
shall be portland cement concrete.
Flexible pavements may be composed of a crushed stone base
course with an asphaltic concrete surface or a full -depth asphalt
structure utilizing a bituminous course.
Rigid structures shall be full depth portland cement
concrete to the designed thickness with a crushed stone
drainage/leveling course of no less than 2 inches.
Pavement sections shall be designed in accordance with the
procedures and criteria of the AASHTO GUIDE FOR DESIGN OF
PAVEMENT STRUCTURES,latest edition, and the criteria contained
herein. Any conflicts shall be resolved in favor of the more
stringent criteria resulting in a stronger and deeper pavement
section.
References to various materials, testing and construction
shall refer to the latest editions of AASHTO, ASTM, and the
Standard Specifications of the Arkansas State Highway and
Transportation Department.
Typical design requirements are summarized in Appendices
nBn
IIAu
4-2 Pavement Materials and Construction:
All pavement materials, construction methods, standards,
time and temperature constraints, seasonal constraints, and
performance requirements shall be in accordance with the latest
edition of the AHTD STANDARD SPECIFICATIONS FOR HIGHWAY
CONSTRUCTION, and this set of requirements (SECTION 4, PAVEMENT
DESIGN) unless specifically approved otherwise in writing by the
CITY ENGINEER for a specific and individual exception. All
testing shall be in accordance with Section 7, Inspections and
Testing.
4-3 Subgrade Material:
Subgrade soils shall be all materials used for subgrade
including in-situ materials and fill materials. Subgrades for
pavement shall be stabilized by mechanical compaction or by other
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methods approved in writing by the City Engineer. Stabilization
methods such as fabrics and chemical stabilization may be
submitted for approval when supported by engineering data and
calculations to substantiate the adequacy of the stabilization
procedure.
The top 24 inches of the subgrade shall be a material not
susceptible to frost action unless modified with cement, lime or
another method approved specifically by the City Engineer to
resist frost action (Soils classified as A-4 and A-5, including
sandy silts, fine silty sand or lean clays are highly susceptible
to frost action).
Methods and procedures for establishing the total depth of
soil replacement and/or modification shall be specified by the
design engineer and included in the project plans and
specifications. The minimum depth of replacement shall be 24
inches in the absence of engineering data showing otherwise.
The adequacy of in-situ soils and fill material as pavement
subgrade shall be evaluated based upon the soils classifications,
liquid limit, plasticity limit and California Bearing Ratio (CBR)
values.
All soils with a liquid limit greater than 40, or a
plasticity index greater than 15, or a CBR value of less than
eight (8) shall be undercut and removed from the street section
or improved by a designed method of stabilization accepted by the
City Engineer.
Soils with a CBR of eight (8) or greater, and classified as
GM or GC soil, shall be accepted as "Hillside" material and no
further treatment or upgrade will be required.
Subgrade compaction requirements including the moisture -
density requirements shall be shown both on the plans and in the
specifications (minimum 95 percent modified proctor required).
Sampling and testing of subgrade materials shall be as set
forth in Paragraph 4.8 of these Standards.
Pavement designs which utilize a subbase course shall
include test data and specifications for the subbase material in
the calculations submitted to the City Engineer for review and
approval.
4-4 Base Course:
Base course material shall be crushed stone meeting the
requirements of AHTD class 7 aggregate base course as specified
4-2