Roadway Standards Section 230 – Residential, Agricultural & Logging Driveway Design

230.1 General

The following standards shall apply to the design of residential, agricultural and logging driveways approaching public or private roadways.  County Code Section 7.030.240 provides some exceptions to the requirements below.  The Entrance Permit Matrix provides additional requirements. 

230.2 Standard Drawings

Driveways that intersect with a proposed or existing sidewalk or other pedestrian facility shall meet ADA accessibility requirements and should be constructed in conformance with the applicable standards depicted in the most recent versions of Oregon Standard Drawings RD725, RD730, RD735, RD740, RD745, or RD750.  Residential, agricultural and logging driveways shall be constructed in conformance with the applicable standards depicted in Standard Drawings D250 through D700. The County shall determine the specific driveway detail, based upon the existing and planned improvements.

230.3 Provisions for ADA Accessibility of Driveways

1. All new or altered driveways required to meet ADA accessibility standards shall meet the PROWAG standards for a Pedestrian Access Route whether or not the driveway is connected to sidewalk or path.
2. The driveway shall provide a connection on both sides to existing or planned sidewalk or path, at a location identified by DTD.
3. The pedestrian access route across the driveway shall be at least 5 feet wide perpendicular to the direction of pedestrian travel with a cross slope of no more than 2% and a grade in the direction of pedestrian travel that does not exceed the grade of the adjacent street.
4. The edge of the pedestrian access route on the driveway shall be flush with the adjacent sidewalk or path with a vertical surface discontinuity of no more than ¼ inch.
5. If it is necessary to provide ramp(s) connecting the driveway pedestrian access route to the adjacent sidewalk or path, the ramp shall have a running slope in the direction of pedestrian travel no more than 8.33%, ramp length not to exceed 15 feet, and cross slope no more than 2%.
6. If the driveway serves commercial uses and is 50 feet or more wide, or stop controlled, or both, truncated dome texture contrast shall be provided perpendicular to the direction of pedestrian travel on the sidewalk on the transition from the adjacent sidewalk or path to the driveway on both sides. The truncated dome texture contrast shall extend 2 feet in the direction of pedestrian travel and completely across the sidewalk.

230.4 Driveway Vertical Geometry

1. For residential driveways, the average driveway grade shall not exceed 12%, and no grade shall exceed 15% for gravel driveways or 20% for paved driveways. 
2. All grades in excess of 12% shall be approved by the fire district. 
3. The grade break for all driveways shall be a maximum of 9%.  Grade breaks in excess of 9% shall require vertical curves with a minimum K value of one (1). 
4. Vertical transitions shall be designed for the design vehicle to not "bottom out" at minimum.  The functionality of the intersecting roadways shall be considered to ensure that vehicles on major roadways are not excessively slowed or endangered by driveway operations. 
5. For residential driveways, vertical clearance shall not be less than 13.5 feet.
6. Steep, uphill driveways having greater than a ten percent grade shall be constructed with diagonal water bars (berms) to assure that water from uphill properties is directed into the ditch line.  In drainage situations which will not be remedied by valley gutters or water bars, it is the responsibility of the owner to construct ditches, etc., to prevent damage to the roadway or danger to the traveling public. 

230.5 Driveway Horizontal Geometry

1. Standard driveway throat widths for agricultural and logging driveways and residential driveways vary from a minimum of 12 feet to a maximum of 35 feet at their intersections with public roadways.  Driveway widths should be minimized.  A truck turning analysis should accompany any design modification requests.
2. Horizontal clearance shall not be less than 20 feet for driveways subject to fire access requirements.
3. Minimum centerline curve radius shall be 50 feet for driveways subject to fire access requirements.
4. Turnaround geometrics shall conform to Standard Drawing C350 or C300, as applicable. 

230.6 Driveway Structural Capacity

For driveways subject to fire access requirements, roadway base, bridges, and culverts shall be capable of supporting a 75,000 pound fire truck.  See Chapter 5 regarding requirements associated with structures such as walls, bridges and other structures.

230.7 Emergency Services

1. All residential and agricultural driveways longer than 150 feet in length shall be designed to provide for fire access and shall be provided with an emergency vehicle turnaround area at or near the driveway termination. 
2. Residential and agricultural driveways with a travel surface less than 20 feet wide and in excess of 400 feet in length shall have a turnout every 400 feet per Standard Drawing C350 at locations approved by the fire district.
3. Gates shall be placed a minimum of 30 feet from back of sidewalk or edge of pavement.  If queues are likely to extend into the travel lane of the nearest roadway, then a queuing analysis shall be provided per Section 295.  Gates may require the approval of the fire district. 
4. Exceptions to these standards are illustrated in the Entrance Permit Matrix.

230.8 Driveway Surface Water

1. Surface water runoff shall not be allowed to flow along or across an access or entrance from private property onto the travel surface of the roadway.
2. Driveways and buildings that increase impervious surface by the thresholds described in Chapter 4 are subject to stormwater management requirements.
3. Requirements for erosion control shall be addressed per Chapter 4.

230.9 Driveway Culverts

1. All driveways on non-curbed roadways shall have culverts for proper road drainage unless Engineering determines that they are not required. 
2. Culvert installations are typically not required on paved and curbed roads.  The installation of driveway culverts to control surface runoff shall be required as deemed necessary by Engineering.
3. Driveway culverts shall provide a minimum 12 inch inside diameter.  Larger culverts are required based upon the design calculations and under the following conditions:
4. Culverts shall be designed to convey storm water from the contributing basin for the 25 year storm at full build-out of the basin.
5. When the existing storm sewer culverts above and below the proposed driveway entry are a larger diameter than l2-inches;
6. When there is evidence that erosion has occurred in the roadside ditch;
7. When there is other evidence to show that a larger diameter would be appropriate.
8. Bedding requirements for concrete and metal culvert pipe shall never be below the Class C bedding specification contained in the Oregon Standard Specifications for Construction.
9. Storm sewer culvert shall have enough aggregate and/or pavement cover to support HS-20 loading per Standard Drawing D250.
10. Notwithstanding the requirements of this subsection, ORS 368.251 to 368.281 shall govern storm sewer culverts and the accompanying entry structure.
11. Culverts shall be maintained in good condition so the flow of storm water is not impeded.

230.10 Intersection Angle

Comply with requirements of Section 250.8.2.

230.11 Permit Requirements

An Entrance Permit or Development Permit, whichever is applicable, shall be obtained from Engineering.

230.12 Inspection Requirements

Comply with requirements of Section 180.

230.13 Intersection Sight Distance Requirements

Comply with requirements of Section 240.

230.14 Maintenance Requirements

The maintenance of existing driveway entries within the right-of-way, including culverts, aggregate, and driving surface, shall be the responsibility of the owner of the property being served by the driveway.  Maintenance must be performed so that the entry does not become a hazard including the responsibility of ongoing management of private property and the right-of-way to maintain sight distance per Section 240.  Additional requirements are provided in County Code Section 7.03.