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Chapter 4
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Design Criteria
4.21 Clearances

Clearances are the minimum distances between elements in, under and above the street right-of-way. Clearance requirements are a key factor in how space within the right-of-way and on private property adjacent to the right-of-way can be used. Maintaining appropriate clear distances between certain elements in the right-of-way and on private property is necessary for a variety of reasons. Safety is a key consideration—for the traveling public, the property owner and for operations and maintenance crews who must access elements in the right-of-way for routine maintenance or repair. Appropriate clearances also enable the proper growth and development of trees and landscaping, and help protect and maintain both overhead and underground utilities.

This section describes required lateral and vertical clearances as well as special circumstances where additional clearance requirements may apply. The minimum clearances defined in this section are requirements. When minimum clearances cannot be met due to site condition constraints, the City staff will work with the applicant to determine an acceptable solution. Deviations from the standard clearances in this section are considered on a case by case basis and are evaluated by SDOT, SPU and other departments as needed.
4.21.1 Links to Standard Plans and Specifications
Standard Plan 030: Standard Location for Utilities (Residential Street)
4.21.2 Design Criteria


Lateral Clearances

From

To

Standard Clearance

Curb face

Closest part of any fixed object (excluding traffic control signs and parking meter posts)

3 feet

Edge of sidewalk

Closest part of any fixed object (excluding traffic control signs and parking meter posts)

1 feet

Textured surface of wheel chair ramp

Closest part of any fixed object (excluding traffic control signs and parking meter posts)

1 feet

Edge of sidewalk

Stair riser

2 feet

Pole face, fire hydrant

Closest part of any fixed object (excluding traffic control signs and parking meter posts)

5 feet

Stop sign

Nearest parking space

30 feet

Obstruction in sidewalk

Closest part of any fixed object (excluding traffic control signs and parking meter posts)

6 feet

Multi-use trail, edge of pavement

Closest part of any fixed object (excluding traffic control signs and parking meter posts)

2 feet (3 feet preferred)

Vertical Clearances

From

To

Standard Clearance

Roadway surfaces

Any horizontal projection over named surface

20 feet

Sidewalk surfaces

Any horizontal projection over named surface

8 feet

Roadway surfaces Tree limbs 14 feet

Roadway surfaces

Bottom of bridge

16.5 feet

Alley surfaces

Any horizontal projection over named surface

26 feet

Bicycle path surfaces

Any horizontal projection over named surface

10 feet

Trees : For more information about clearances and trees, including conditions for deviating from the standard clearance listed below due to site constraints; refer to Section 4.14.2 Clearances from Street Trees. Factors to consider for a deviation from the standard required clearances between street trees and utilities may include the depth and age of the pipeline, the possible use of root barriers, the nature of the plantings, fire code requirements, and other factors.

Clearances from Trees

From

To

Standard Clearance

Centerline of Tree

Face of curb

3.5 feet

 

Sidewalk or sidewalk landing

2 feet

 

Driveway (measured from edge of driveway at sidewalk)

7.5 feet

 

Edge streetlight poles

20 feet

 

Edge of fire hydrants

5 feet

 

Edge of utility poles

10 feet

 

Extension of cross street curb at an intersection

30 feet

 

Underground utilities

5 feet (except ducts and gas pipes as shown on Seattle Standard Plan 030 for residential streets)

 

Roadway edge, where no curb exists

10 feet

Railroad clearances: Certain requirements apply if a project is in the on, over, under, or in the vicinity of land or facilities owned and/or operated by railroad operators. There are three reference points for determining clearances: 1) the franchise agreement for a particular piece of railroad in the right-of-way; 2) state requirements; and 3) federal requirements. Whether state or federal (or both) requirements apply depends on the track classification and function.

Clearances from Railroad Facilities

From

To

Standard Clearance

Centerline of railroad track

Any obstruction 6” or more in height

Minimum lateral clearance of 8.5 feet (10 feet desired). This clearance shall be increased 1.5 inches for every degree of track curvature

 

Sidewalk or sidewalk landing

2 feet

 

Driveway (measured from edge of driveway at sidewalk)

7.5 feet

Other clearances pertaining to railroads shall conform to Clearance Rules and Regulations Governing Common Carrier Railroads prescribed by the Washington Utilities and Transportation Commission. Minimum clear distance above a railroad track shall be 23 feet.

If your project is on or adjacent to property owned by railroad operators, contact the operator for information about required clearances or additional permit requirements.

Bicycle parking clearances: In addition to the clearances defined in the table below, bicycle parking facilities must not encroach upon a minimum of 6 feet of clear sidewalk space. Narrow racks such as the inverted-U rack, must have a total minimum combined clearance of 6’ around the rack, measured from any point on the rack.

Standard Clearances from Bicycle Parking

From

To

Standard Clearance

Bicycle parking

Curb when adjacent to parking

3 feet

 

Curb when adjacent to vehicle travel lane

2 feet

 

Street trees and street furniture for the rail-type rack

1 foot

Electrical utility clearance requirements: Applicants who are developing a new project must pay attention to the potential conflicts between existing electrical facilities in the public right-of-way and their new building during project planning, design, demolition and construction. The following criteria applies:

Minimum horizontal and vertical clearances between overhead power distribution and buildings or other structures: The Seattle City Light (SCL) Overhead Power Distribution requires a minimum horizontal and vertical clearance from buildings and structures. The purpose of this clearance is to keep the general public and workers without high voltage electrical expertise out of harms way.

Clearances also provide adequate space for qualified electrical workers to operate safely and efficiently during construction and long term operations and maintenance activities. Additional clearances are required to allow for regular building maintenance such as window washing activities.

Zero lot line developments: Zero lot line developments often encounter clearance problems with high voltage overhead and underground electrical facilities and wires. Land use setback requirements alone, for example when minimal front yard setbacks are allowed, are likely not adequate to account for required clearances from overhead electric utilities. Note that clearances are also required where electrical facilities are located in alleys. Thus proposed buildings may need to be located further back from property lines to accomplish required clearances.

Permit applicants must adhere to electric utility clearance requirements. Please contact Seattle City Light to arrange a meeting as early as possible in your design process. We recognize that each proposed development location, adjacent utilities, streetscape, and development request is unique. Even if poles and wires are not immediately adjacent to your property at this time, it is best to assume clearances are needed until you meet with Seattle City Light and verify otherwise. Additional and relocated infrastructure will be needed to serve the demand for growth.

Refer to Figure 4-23: Seattle City Light Utility Clearance.
Refer to Electrical Utility Clearances Notes.

4.21.3 Design Considerations

The applicant is advised to document the existing site conditions early in the design phase to identify any elements that may have a required clearance to help avoid possible costly site modifications during permitting.

continue to section 4.22 »   
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Detailed Table of Contents
Chapter 4
Design Criteria
4.1 Introduction
4.2 Street Classifications and Street Types
4.3 Design Criteria General Notes
4.4 Grading
4.5 Design Cross Section
4.6 Roadway Width
4.7

Roadway Pavement

4.8 Intersections
4.9 Driveways
4.10 Curbs
4.11 Sidewalks
4.12 Crosswalks
4.13 Bicycle Facilities
4.14 Street Trees and Landscape Architectural Standards
4.15 Introduction to Utilities Design Criteria
4.16 Street Lighting
4.17 Street Drainage, Storm Drains and Sewers
4.18 Water Mains
4.19 Fire Protection
4.20 Seattle City Light
4.21 Clearances
4.22 Structures in the Right-of-Way
4.23 Cul–de–sacs and Turnarounds
4.24 Traffic Operations
4.25 Transit Zones
4.26 Street Furniture, Public Art and Unique Objects in the Public Right-of-Way
4.27 Access Easements
4.28 Contact Information
   
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