Chapter IV. Design & Construction Standards
Sec. 104-1 Alignment Criteria for Streets
104-1.01 Minimum centerline radius of horizontal curvature shall be as follows:
- Arterial/Collector Streets – 2000 feet.
- Local or Industrial Streets – 500 feet.
- Limited exceptions to the above minimums may be approved by the Director when topography or other conditions warrant within the following limits:
- Arterial and Collector Streets not less than 300 feet.
-
In mountainous areas, minimum local streets radii may be reduced to 100 feet or as approved by the Director. Curve widening to provide adequate sight distance shall be determined by the Director.
104-1.02 Intersections
-
Streets shall intersect at right angles where practicable. When topography or other physical feature makes this requirement impracticable, a Limited Exception may be granted by the Director. In general, the maximum deviation which may be granted shall not exceed 15o skew beginning at the ultimate curb line from a right-angle intersection. A knuckle shall be considered an intersection for skew angles, along with roundabouts, see Section 104-1.04.
- Curb return radii shall be:
- Residential and commercial = 30 feet
- Industrial = 50 feet
Wheel path plots of the design vehicle shall be provided to verify the curb return radii as required by the Traffic Engineer.
- Property line cut off at intersections shall be in accordance with Plate No. R-41.
- Where the angle of intersection is acute, or where a sight distance problem may be anticipated, an increased property line cutoff may be required by the Director.
- All streets entering upon any given street shall have their center lines directly opposite each other or separated by at least 150 feet, see Plate Nos. R-48 thru R-50.
- Tangent distance between end of horizontal curve and intersection centerline shall be a minimum of 150 feet.
104-1.03 Dead-end streets in excess of 150 feet in length shall be constructed to permit vehicles to turn around at the end. The Director may increase the length to 200' providing no access is provided by the road. The maximum length of a dead-end street, including all dead-end streets accessed from that dead-end street shall not exceed the following cumulative lengths, regardless of the number of parcels or tracts served:
- Zoned for less than one acre 800 feet
- Zoned for 1 acre to 4.99 acres 1320 feet
- Zoned for 5 acres to 19.99 acres 2640 feet
- Zoned for 20 acres or larger 5280 feet
Where a dead-end street serves areas in which several different length limits could apply because of several different parcel sizes, the shortest allowable length shall apply.
104-2.01 Roundabouts
Roundabouts generally have the following characteristics:
-
A circular travel lane operating in a counter-clockwise direction for collecting and distributing traffic
- A raised center island
- Mountable apron
- Channelized approaches
- Yield control at all approaches
- Tapered approaches to encourage entering vehicles to travel in the correct direction through the circular travel lane
The use of roundabouts is primarily constrained by traffic volumes and by geometrics, therefore roundabout design shall be in accordance with the National Cooperative Research Program (NCHRP) Report 672, current edition and the California Department of Transportation (CALTRANS) Highway Design Manual (HDM), Section 405.10 (ROUNDABOUTS), current edition and Plate R-57. It is understood that roundabouts are not appropriate for all traffic conditions and intersection volumes, therefore requests for roundabouts will be processed through the Traffic Engineer with final approval given by the Director.
When constructed in appropriate locations based on criteria contained herein, roundabouts can provide increased efficiency of operation, enhanced safety, cost savings, enhanced aesthetics, and diminished impacts on surrounding property and the elimination of conflict points.
Sec. 104-2 Gradient
104-2.01 Minimum grade on any street or alley shall be 0.5%. Where concrete curb and gutter or gutter in the case of an alley, is constructed, minimum grade shall be 0.2%.
104-2.02 The maximum grade on any street or alley shall be as follows:
- Arterial and Collector Streets - 6%.
- Local Streets and Residential Cul-de-sac Streets (including street turning area) - 8%.
- All classes of Industrial and Commercial streets - 8%.
- Alleys - 8%.
Exceptions to the maximum or minimum grades may be granted by the Director as follows:
- Arterial and Collector Streets - 8% maximum.
- Local and Cul-de-sac Streets (excluding street turning area) - 15% maximum.
- All classes of Industrial or Commercial Streets - 8% maximum. (No exceptions allowed).
- Alleys - 15% maximum.
104-2.03 Superelevation shall be provided for all streets where required by the Director.
104-2.04 Vertical curves shall be as follows:
- Residential and Industrial streets shall be designed to provide a minimum stopping sight-distance corresponding to a design speed of 25 MPH.
-
Arterial and Collector streets shall be designed to accommodate minimum vehicle speeds of 65 MPH. An exception may be granted by the Director to reduce the vertical curve design speed.
- Vertical curves shall be used when change in grade exceeds 0.50% and shall have a minimum length of 50 feet.
- Alleys shall be designed for 20 MPH stopping sight distance.
- The sight distance to be used for all streets and highways, including vertical curves, shall be in accordance with the current edition of California Department of Transportation Highway Design Manual.
104-2.05 The maximum grade for cul-de-sac street turning area shall be 8%.
104-2.06 The maximum grade through any intersection of two streets shall be 8% within the intersection (P.I. to P.I.).
104-2.07 When any road is extended to a subdivision boundary for the purpose of providing a future connection to adjoining property, the subdivider shall submit an alignment and profile demonstrating the feasibility of such future extension. (Minimum distance beyond tract line shall be 100 feet, 200 feet in mountains).
104-2.08 The minimum grade for any cross gutter shall be 0.35% measured from BCR to ECR.
Sec. 104-3 Grading
104-3.01 Roadways shall be graded by the developer to full width as shown on the standard typical cross-sections.
104-3.02 The maximum grade tolerance in roadway sections for aggregate base, aggregate subbase and original ground shall be 0.05 of a foot high.
104-3.03 Grading beyond the right-of-way may be required by the Director to provide for safe sight-distance, stability and to control drainage.
104-3.04 All grading or excavating in an existing county road, city street, or state highway shall be first authorized by a valid encroachment permit.
104-3.05 Where improvements are required outside of the right-of-way as part of the development improvements, the subdivider shall provide satisfactory easements to allow construction and/or maintenance of the improvements. The easements shall conform to all subdivision requirements including, but not limited to, free and clear dedication, removal of obstructions and guarantee of title.
Sec. 104-4 Pavement, Structural Sections
All streets shall be surfaced by the developer in accordance with the following specifications:
104-4.01 Streets shall be designed in accordance with Chapter III "Street Improvement Requirements" of these standards and the following sections.
104-4.02 Road surfacing on all classes of streets and alleys shall be of asphalt concrete, except as hereinafter provided.
- Road-Mixed Asphalt Surfacing (RMAS) may be used, in lieu of asphalt concrete, in those areas of the County more than 50 miles along the shortest practical route from a commercial asphalt concrete plant.
- RMAS shall conform to design mix approved by the Director.
- Minimum thickness of a road-mixed asphalt surfacing shall be 0.25 foot.
- Alleys: Surfacing shall be of asphalt concrete or RMAS, whichever is used in the streets of the development.
- The minimum thickness of aggregate base or aggregate subbase shall be 0.35 foot.
104-4.03 Aggregate Bases - In addition to the specified R-Value for aggregate bases, the R-Value at 150 psi exudation pressure shall be 90% of the R-Value at 300 psi exudation pressure.
Sec. 104-5 Utility Placement Within Streets
Underground utilities including services to be installed in streets shall be installed prior to surfacing of the streets.
The minimum cover of any underground utility within a street right-of-way shall be 30 inches.
Sec. 104-6 Street Lights
All street lights installed shall be light emitting diode (LED).
Unless otherwise approved by the Director, street lighting to be designed in conformance with these specifications, RP-8, “American National Standards Practice for Roadway Lighting, Illuminating Engineering Society of North America, Kern County Zoning Ordinance and/or other approved design guidelines.
All material and work shall conform to the requirements of the California Electrical Code, National Electrical Code, and other pertinent codes and regulations.
104-6.01 Residential Areas - Street lights shall be located at intersections, at midblock with blocks greater than 600 feet between intersections, at ends of cul-de-sacs greater than 150 feet in length, and on curved streets as required by the Director. Street lights on arterial and collector streets or intersections with an arterial street shall be 9,500 lumens. Street lights on local streets shall be 5,800 lumens. Lumen output and light sources may vary depending on new technology. Street lights shall have an acceptable maintenance entity formed and be energized prior to acceptance of the improvements. Street light construction shall be in accordance with Plate No. R-75 unless approved otherwise by the Director.
104-6.02 Commercial and Industrial Areas - Street lights shall be located at intersections and ends of cul-de-sacs greater than 150 feet in length. Luminaires shall be as provided in the above paragraph.
On all streets, the pull box shall be installed, and the light wired from the pull box at the pole per Plate No. R-76. Electrical service shall be provided to the street light from the adjacent parcel (on either side of the street) as it is developed. Electrical service easements shall be granted as required. Street lights shall be installed per Plate No. R-75.
104-6.03 Additional street lights - In commercial, industrial, or residential areas, additional street lights shall be installed as required by the Director.
104-6.04 Street light shall be installed at post office approved community mailboxes.
104-6.05 Street light shall be installed at all passenger bus loading/unloading zones.
104-6.06 All County Service Area maintained street lights shall be Rate Schedule LS2 “PG&E – owned street and Highway Lighting”. Rate and Ownership of street lights shall be verified by the Public Works Department. Luminaires shall be full cutoff optics.
104-6.07 Street light location plan and general plan details shall be submitted for review and approval by the engineer. The plans shall show and identify all street lights to be installed, distance between poles, height of poles, wattage of lamps, lumens, type of luminaire, irrigation pedestals and all other pertinent information. Also, all existing street lights within 400 feet of the project shall be clearly identified and shown on the plans.