Appendix 302. PUBLIC STREETS

302.1

Street Construction

Public streets shall be constructed in accordance with the typical cross section shown in Appendix 1.

302.1.1

Grading

Before grading is started, the areas between the proposed slopes shall be cleared of all trees, stumps, roots, weeds, logs, heavy vegetation, and other objectionable matter, and shall be grubbed to a depth below the proposed grade in cuts and the natural ground in fills so as to expose suitable subgrade. The objectionable matter shall be removed from within the right-of-way limits and disposed of in such a manner that it will not become incorporated within the fills, nor in any manner hinder proper operation of the storm drainage system.

All suitable material may be used in the construction of embankments or at any other place needed. If rock is encountered, it shall be removed to a depth of not less than 12" below the subgrade of the road bed. Where boulders are encountered, they shall be removed 6" below the proposed subgrade.

Prior to road construction, all underground work that is to be within the roadway shall be completed. This includes all drainage, sewerage, water, telephone, electrical, and other utility mains to the end that the completed roadway will not be disturbed for the installation of any utility main. All utilities under paved areas are to be backfilled with stone.

302.1.2

Subgrade

The subgrade shall be prepared to the lines and grades as designed and staked by the Subdivision surveyor or engineer/surveyor to correspond to the cross section of the bottom of the base as indicated on the typical cross section approved by the Governmental Engineer.

After the subgrade has been appropriately prepared and shaped, it shall be thoroughly rolled and then clipped with a grader until final lines and grades are obtained. Water shall be added to the subgrade if the material is dry and will not readily compact under the roller. All material so determined by the Governmental Engineer to be unacceptable and all soft yielding material that does not readily compact under the roller shall be removed. All holes or depressions caused by the removal of this material shall be replaced with suitable material and rolled under until compacted to the satisfaction of the Governmental Engineer. The subgrade shall be compacted to 95% standard proctor to conform with the accepted cross section and grade.

302.1.3

Embankments

Any street, upon which an embankment is to be constructed, having more than a 3 to 1 slope, shall be plowed or scarified completely and rolled thoroughly with a sheep-foot roller, if applicable. Each layer of embankment formation shall be compacted before the formation of the next layer is begun.

Each layer of embankment is to be constructed with a thickness not to exceed 8", and shall be compacted at optimum moisture content to 95% standard proctor.

If, in the event any section of embankment appears not satisfactory in respect to compaction, the developer or contractor will be required to have a compaction analysis performed by a recognized authority and the repair work carried out as directed by this analysis.

302.1.4

Base

Before the base operation is begun, the Governmental Engineer will make an inspection of the subgrade. Approval of the subgrade is required prior to the placing of any base material. The base shall be constructed of crushed stone 33 p (T.B.R.), or pug mill mix.

The crushed stone shall be applied at the rate of 110 pounds per square yard per inch of thickness. Compaction shall be attained with a pneumatic roller, sheep's-foot roller or other similar compacting equipment. The minimum thickness shall be 6" compacted, where, in the opinion of the Governmental Engineer, the subgrade is sufficient to use this amount.

Weight tickets shall be furnished to the Governmental Engineer. The crushed stone shall be placed with approved spreader box or approved method at the discretion of the Governmental Engineer. Then the stone shall be laid out to the lines and grades of the roadway and thoroughly rolled until a bond has formed and the excess moisture is gone. Alternate clipping with the grader and rolling shall be performed until true lines and grades are attained.

302.1.5

Prime

After the base course has been thoroughly compacted and worked to the lines and grades as shown on the typical cross section, it shall be dampened if necessary.

Prime alternates are as follows:

Type and Grade	Application Temperature
R. C. -1	90—110
R. C. -2	120—150
A. E. -1	100—125

 

The type and grade of prime material shall depend on the condition of the base course and shall be designated by the Governmental Engineer.

Rate of application shall be 0.25 to 0.35 gallons per square yard.

If RT-1 or -2 is used, there shall be a curing period before the surface treatment is begun. The length of curing period shall depend on the season of the year and weather conditions. The Governmental Engineer shall determine when the prime is cured and the surface treatment can be started.

Immediately after the prime material has been applied, mineral aggregate (size 15 or 16) shall be spread at the rate of 25 to 30 pounds per square yard. Then a steel wheel roller shall roll the aggregate into the prime material. Seasonal limitations on prime are from March 1 to December 1.

302.1.6

Surface

A minimum of six (6) inches thick asphaltic concrete pavement shall be applied over the prime.

A.

The asphalt and mineral aggregate for the surface course shall be a minimum of two (2) inches in thickness (after compaction) and shall conform to the Tennessee Department of Highways Specification, Item 411E, Traffic Bound Surface Course.

B.

The asphalt and mineral aggregate for the binder course shall be a minimum of four (4) inches in thickness (after compaction) and shall confirm to the Tennessee Department of Highways Specification, Item 307B, Binder Course.

302.1.7

Seasonal Limitations of Asphalt

The outside temperature away from artificial heat and in the shade shall be 40°F. and rising for plant mix. Plant mix road will be 220 pounds per square yard. Weight tickets shall be furnished to the Governmental Engineer.

302.1.8

Record Street Design

The developer or surveyor/engineer shall submit to the City Engineer's Office acceptable record street design plans including detailed design of entrance islands, right-of-way islands, split roads, cul-de-sac islands, drainage pipes and other drainage facilities in roads and curb to curb paving width. The City Engineer may require bond in an amount and form sufficient to complete these record plans if they have not been submitted and approved when the transparent plastic film copy and other copies of the final plat to be recorded are signed.

302.2

Street Classification, Right-of-Way Widths, and Pavement Width

302.2.1

Classification

Streets are classified as major streets, collector streets, local streets, short cul-de-sacs and split streets, (See Article 6, Definitions)

302.2.2

Right-of-Way

The right-of-way for a street is the area between facing lots and offered to the local government for use by the public.

302.2.3

Pavement Width

The pavement width shall be measured from the inside face of the curb to the inside face of the curb.

302.2.4

All streets proposed by the developer shall be built at least to the standards specified in the chart below.

Classification	Right-of-Way Width in Feet	Pavement Width in Feet
Principal Arterials	100	80 (two 33 foot roadways with six lanes of 11 feet, with a 14 foot median/turn lane)
Minor Arterials	80	58 (two 22 feet roadways with four lanes of 11 feet each with a 14 foot median/turn lane)
Collector Street	60	with no driveway - 30 with driveways on one side - 36 with driveways on both sides - 44
Local Streets	50	26
Short Cul-de-sacs	40	22
Split Streets	Varies	18 each level
(Sec. 660.9 App. A-1)	(60 min.)

 

302.2.5

Cul-de-Sacs

302.2.5.1

Cul-de-Sac turnarounds (See App. 6)

Cul-de-sac turnarounds shall be designed and built according to at least the following standards:

Cul-de-sacs without a planted median:

Description	Right-of-Way radius in feet	Pavement radius in feet
Regular Cul-de-Sacs	50	40
Cul-de-Sacs where school buses must turn around	60	50
Short Cul-de-Sacs	40	30

 

302.2.5.2

Cul-de-sacs with a planted median : ^[**]

Description	Maximum radius for planted median in feet	Pavement width on all sides of median in feet	Width of ROW beyond edge of pavement in feet	ROW radius in feet
Regular Cul-de-Sacs	20	20	10	50
Cul-de-Sacs where school buses must turn around	22	28	10	60

 

302.2.5.3

If a cul-de-sac is of a temporary nature and a further extension into adjacent land (owned by the developer) is planned, then the roadway of the turnaround outside of the normal paving width may be gravel, and the property in the turnaround right-of-way outside of the normal right-of-way width shall be a temporary dedication to abutting property owners when the cul-de-sac is extended into the adjacent land and accepted by the local government. When the temporary cul-de-sac turn-around is extended, the developer shall repair any broken pavement, install the required curbs and gutters on the regular paving width of the street and restore the shoulder (front yard).

302.2.6

Widths of existing streets

On existing streets, property lines shall be located with iron pins at the corners of all lots, at least 25 feet from the center line of roadway unless the Governmental Engineer or City Manager permits a narrower right-of-way.

302.2.6.1

If the subdivision is located on both sides of the existing street, fifty (50) feet shall be dedicated and the drainage facilities in the street shall be improved to the point that the increased runoff water caused by the development of the subdivision will be accommodated to the satisfaction of the Governmental Engineer.

This dedication requirement may be waived by the Governmental Engineer or City Manager if he deems a narrower right-of-way to be acceptable by signing a "Transparent plastic film" showing such a narrower right-of-way.

302.2.6.2

If the subdivision is located on only one side of an existing street, twenty-five (25) feet measured from the center line of the existing right-of-way shall be dedicated and the drainage facilities in the street shall be improved to the point that the increased runoff water caused by the development of the subdivision will be accommodated to the satisfaction of the Governmental Engineer.

This dedication may be waived by the Governmental Engineer or City Manager if he deems a narrower right-of-way to be acceptable by signing a "Transparent plastic film" showing such a narrower right-of-way.

302.3

Street Extensions

302.3.1

Extensions of Existing Platted Streets

The arrangements of streets in new subdivisions shall provide for the continuation of existing, proposed, or platted streets in adjoining areas, where feasible, as determined by the Planning Commission.

302.3.2

Future or Proposed Street Right-of-Way

Street right-of-way marked "future street," "future right-of-way," "proposed street," or "proposed right-of-way," etc., shall not be considered to be dedicated to the government. Ownership of these "right-of-way's" is retained by the developer. The developer of adjacent land who wishes to gain access through a future or proposed street shall negotiate to purchase the proposed street or right-of-way from the current property owner and shall construct said street.

302.3.3

Half Streets

Dedication of one-half (½) of the rights-of-way (half streets) for streets proposed along the boundaries of a subdivision shall be prohibited.

302.4

Curves and Sight Distances

302.4.1

Horizontal Curves

Where a deflection angle in the alignment of a road occurs, a curve shall be introduced. On major streets the center line radius of curvature shall not be less than seven-hundred (700) feet; on collector streets, not less than three-hundred (300) feet; and on local and short cul-de-sac streets, not less than one-hundred (100) feet.

302.4.2

Vertical Curves

Every change in grade shall be connected by a vertical curve. In general no sight distance of less than 200 ft. on vertical curves shall be allowed.

302.5

Street Intersections

302.5.1

Angle of Intersection

The center line of all streets shall intersect at as nearly a ninety-degree angle as possible, but the angle of intersection shall not be less than seventy-five (75) degrees nor greater than one hundred five (105) degrees, unless approved by the Planning Commission in accordance with the recommendation of the Governmental Engineer.

302.5.2

Centerline Offset of Adjacent Intersections

The use of four-way intersections of local streets with local streets shall be discouraged where possible, and the use of T-intersections shall be encouraged. Regardless of the type intersections employed, however, the centerlines shall be aligned (four-way intersection) or offset up to ten (10) feet or more than one hundred twenty-five (125) feet.

302.5.3

Corner Radii

Curb radii at street intersections shall not be less than fifteen (15) feet. Right-of-way radii at street intersections shall not be less than twenty-five (25) feet. If, because of exceptional conditions, a modification is granted permitting an angle of intersection, less or greater than the standards of Section 302.5.19 then the minimum radii shall be increased or decreased to afford good design and safety.

302.5.4

Grades Approaching Intersections

Street grades approaching intersections shall not exceed four (4) percent for a distance not less than that shown in the following table, measured from the edge of pavement of the intersecting street:

Types of Intersecting Streets	Distance in Feet
On local at local, includes all other street types not given below	30
On local at collector	35
On local at major	35
On collector at local	35
On collector at collector	60
On collector at major	60

 

302.5.5

Sight Distance at Intersections

In general, sight distances of less than 200 feet shall not be permitted at any street intersection including street intersections in the subdivision and the intersection of a subdivision street with any existing street.

302.6

Street Grades

In general, roads shall be planned to conform to existing topographic conditions. Grades on major roads shall not exceed 12 percent. Grades on other roads may exceed 12 percent for a distance up to 400'; but not over 15 percent. In extreme topographic conditions, grades above 15 percent may be allowed by the Planning Commission prior to construction. If necessary, a letter requesting road grade variances shall be submitted to the Planning Commission staff with the preliminary plat. The letter shall conform to the requirements for a variance letter listed in Article 1, Section 111.

302.7

Street Pattern

All subdivisions shall provide for convenient access and circulation. No lot in each unit or phase of a subdivision may be more than one-thousand three hundred (1300) feet from a potential school bus route that does not require school buses to back up. This shall be accomplished by one or more of the following:

(a)

looped street patterns

(b)

turn-around designed for school buses at "midpoints" in long cul-de-sacs, or

(c)

cul-de-sac turn-around designed for school buses.(see 302.3.5)

302.8

Street Names

302.8.1

Continuation of Streets

New streets that are in, or essentially in, alignment with an existing street shall be given the name of the existing street.

302.8.2

Duplication

The name of a new street shall not duplicate or approximate, by means of spelling, pronunciation, or by use of alternate suffixes or prefixes (such as North, South, Lane, Way, Drive, Court, Avenue, or Street) any existing or platted street name in Hamilton County.

302.8.3

Approval of Street Names

No street names shall be used unless approved by the Planning Commission.

302.9

Street Signs

Street and Name Signs must be of a type approved by the City Manager or Governmental Engineer, and signs shall be installed by the developer.

302.10

Curbs

302.10.1

Asphalt Curbs

Asphalt curbs are prohibited

302.10.2

Concrete Curbs

Concrete curbs shall be installed by the developer in accordance with the specifications in Appendix 2 or 3.

302.10.3

Back Fill

The developer shall have back fill on both sides of the street to the top of the curb.

302.10.4

The homebuilder shall be responsible for repair of any damage to streets, roads, gutters, curbs, and drainage easements to the satisfaction of the Governmental Engineer when the damage was caused during construction of the building.

302.11

Sidewalks and Pedestrian Ways

302.11.1

In residential and non-residential subdivisions, sidewalks or pedestrian ways are not required. In the event the developer desires to install sidewalks or pedestrian ways, they shall meet the following requirements:

302.11.2

In residential areas, sidewalks for pedestrian ways shall be Portland cement concrete, six (6) inches thick and four (4) feet wide.

302.11.3

In commercial areas, sidewalks shall be concrete, six (6) inches thick and six (6) feet wide.