§ 21.5-123. Streets.

(1)

Pavement design. All streets shall be designed to provide a hard surface course, base course and subgrade or subbase course. The pavement design section shall be based on an accepted method of engineering analysis which considers subgrade conditions reflected in a California Bearing Ratio (CBR) test(s), the projected traffic load, and minimum axle load for the type street under consideration.

(2)

Design axle loads. All streets shall be designed to accommodate the following minimum single axle loads based on the type street under consideration:

Street Type	Minimum Single Axle Design Load (pounds)
Arterial,	to be determined based on projected traffic counts
Collector	18,000
Local	12,000
Cul-de-Sac	12,000

 

(3)

Design life. All roadway pavements shall be designed for a twenty (20) year design life.

(4)

Minimum lane and shoulder width. All streets shall have a minimum of two (2) driving lanes to accommodate bidirectional flow traffic. The following minimum lane and shoulder widths shall apply to all streets:

Street Type	Minimum Width of Each Driving Lane (feet)	Minimum Shoulder Width (feet)
Arterial	12	8
Collector	11	5
Local	10	5
Cul-de-Sac	10	5

 

(5)

Surface course. All subdivision streets shall be constructed with a hard surface course consisting of asphalt, Portland cement concrete or asphaltic concrete of a thickness established by the pavement design analysis.

(a)

The minimum thickness for an asphalt or asphaltic concrete street shall be two (2) inches.

(b)

The minimum thickness for a nonreinforced Portland cement concrete street shall be six (6) inches.

(6)

Base course. All subdivision streets shall be constructed with an authorized base course of a minimum thickness established by the pavement design analysis as follows:

(a)

Asphalt streets. Base course shall be stabilized cement, sand-clay-gravel, or crushed stone with a minimum thickness of eight (8) inches.

(b)

Concrete streets. Base course shall be washed sand, asphalt, stabilized cement, or crushed stone with a minimum thickness of four (4) inches.

(7)

Subgrade or subbase course. All streets shall be supported on a subgrade consisting of stable soil or on a subbase course consisting of asphalt, stabilized cement or a select fill material.

(8)

Curbs and gutters. At the option of the developer, concrete curbs and gutters may be provided in lieu of shoulders and open roadway ditches. If provided, concrete curb and gutter sections shall not be considered a part of the required driving lane and shall be one of the following types as approved by the director of public works:

(a)

Roll-over curb and gutter. Shall be of a mountable curb design as specified in the public works manual with a width of two (2) feet.

(b)

Barrier curb and gutter. Shall be of a barrier curb design as specified in the public works manual with a width of one (1) foot six (6) inches.

(9)

Maximum street grade. Street grades shall conform in general to the terrain and shall be sufficient for adequate surface drainage. No street grade shall be greater than eight and five-tenths (85/10) per cent.

(10)

Open roadway ditches. All open roadway ditches shall be constructed with a "V" bottom or flat bottom and shall run parallel with the adjacent street. The maximum ditch foreslope shall be 3:1, the maximum ditch backslope shall be 2:1.

(11)

Turnaround pavement. All turnarounds shall be of the same design and construction as the adjoining roadway. Curb and gutter turnarounds shall have a minimum forty (40) foot radius to the back of the curb. Open roadway ditch turnarounds shall have a minimum thirty-eight (38) foot radius to the edge of the driving lane pavement.

(12)

Pavement return radius. The minimum return radius for all pavement at street intersections shall be twenty-five (25) feet to the outside edge of pavement or driving lane.

(Ord. No. 7985, 11-11-85; Ord. No. 8022, § 6, 6-16-86; Ord. No. 8385, 3-13-95)