1. A “principal driveway” is defined as a private road or driveway serving more than four units, exceeding a length of one hundred feet or exceeding an alternative length as may be determined by the fire chief under subsection (B)(1) of this section.

2. All principal driveways shall be designed with two traffic lanes over the entire length and shall be a loop, cul-de-sac, or hammerhead design, or have other provisions for turning vehicles, such as a garbage or fire truck as approved by the fire chief.

3. Where no on-street parking is permitted, principal driveways shall be a minimum of twenty feet wide curb to curb, or if gutters are required, lip-to-lip of gutters. Where parking is permitted on one side, the width shall be increased to twenty-eight feet curb to curb and with parking on both sides the width shall be increased to thirty-two feet curb to curb. The minimum centerline radius of curvature shall be twenty-five feet. The maximum grade shall be seven percent within twenty feet of a garage or carport and fifteen percent elsewhere. The maximum length of a cul-de-sac principal driveway shall be four hundred feet.

4. The structural section for principal driveways shall be designed on the basis of “R Value” of base soil and a calculated traffic index if not less than 4.5.

5. Principal driveways shall be bordered with a concrete curb or flush concrete edging on each side. Vertical concrete curbs and gutters or concrete valley gutters shall be used where stormwater runoff is involved. Alternates providing pavement edge protection and drainage conveyance structures will be considered by the public works department. Vertical curbs or alternatives may be required where necessary to protect landscaping or buildings from damage by vehicles.

6. Connections of principal driveways to public streets shall be designed to provide for safe and efficient movement of the expected traffic volumes. Driveway width, curb return radii, control of turning movement and similar features shall be subject to approval of the department of public works.

7. Backfill of all trenches in all principal driveways shall meet city public street standards for trench backfill.

1. A “minor driveway” is defined as a private road or driveway serving four or less units and not exceeding a length of one hundred feet, unless additional length approved by the fire chief.

2. A minor driveway shall be at least twelve feet wide from edge to edge and shall have a maximum grade of seven percent within twenty feet of a garage or carport and fifteen percent elsewhere. The minimum centerline radius of curvature shall be twenty-five feet. The structural section for minor driveways shall be designed on the basis of “R Value” of base soil and a calculated traffic index of not less than four.

3. Minor driveways shall be bordered with redwood or pressure-treated headers, concrete curbs or flush concrete edging.