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Chapter 4
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Design Criteria
4.5 Design Cross Section

The design cross section defines the location of the standard right-of-way elements (existing and proposed) for a project location. The standard elements are illustrated in Figure 4-1: Standard Design Cross Section and include but are not limited to: right-of-way line and width, roadway width, planting strip and shoulder, catch line, existing and new grade, slope line, sidewalks, street tree, curb, gutter, crown, depression line, thickened edge, pavement, water main, sanitary sewer and storm drain.

4.5.1 Links to Standard Plans and Specification

030 Desirable Locations for Utilities (Residential Street)
400 Half Section Grade
401 Residential Pavement Section
402 Commercial Arterial Section
403 Roadway Cement Concrete Alley Pavements

4.5.2 Design Criteria

Required Cross Sections for Street Improvement Plans: SDOT requires that street improvement plans include a typical dimensioned cross section. Proposed street and alley improvements require dimensioned cross sections as follows:

  • at all driveways; and
  • at all building entrances located within 10 feet of the property line.

In addition, if a new curb, street widening, roadway alignment, or roadway profile changes are being proposed, cross sections shall be provided for every 25 feet along the length of the improvement.

All cross sections shall be stamped and signed by the Project Design Engineer.

Description of Required Elements : The design cross sections shall describe the following:

  • existing and proposed grades, with spot elevations provided at the centerline;
  • existing edge of pavement;
  • gutter line or flow line;
  • top of curb or thickened paved edge;
  • back of sidewalk;
  • property lines;
  • catch lines; and
  • any retaining walls or rock facing.

Elevations: Existing elevations shall be based on current survey data.

Cross Slopes: The standard cross slopes are identified in the table below.












Sidewalk and
Planting Strip






In areas where the pavement width is being added to an existing street or must vary to accommodate existing infrastructure, the slopes may vary within the minimum and maximums provided above.   When an alley is part of an ADA accessible route, a portion or the entire the cross slope may need to be adjusted to meet current ADA standards.

4.5.3 Design Considerations

Whenever possible, street improvements shall conform to the standard right-of-way cross section described in Figure 4-1: Standard Design Cross Section.

continue to section 4.6»   
Latest Online Manual
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

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 Culdesacs 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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