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Chapter 4
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Design Criteria
4.23 Turn arounds and Cul-de-Sacs

When an existing right-of-way is not platted through from street to street, or when topography or other conditions preclude a street from being improved to its full street-to-street length, a cul-de-sac or other vehicular turnaround shall be provided. Cul-de-sacs are required at all street dead ends, and turnarounds are required at private access easement dead ends.

4.23.1 Links to Standard Plans and Specifications

N/A

4.23.2 Design Criteria

Determination of through street: DPD, in consultation with SDOT, shall determine when a street does or does not have the potential to become a through street. When a street does not have the potential to go through a cul de sac or turnaround is required.  Dedication of additional right-of-way width may be required to accommodate the turnaround.

Cul-de-sac and turnaround design: Refer to Figure 4-25: Cul-de-sacs for passenger vehicle cul-de-sac designs and Figure 4-26: Alley and Easement Turnarounds for turnaround designs approved by the SDOT Traffic Engineer.  

Turnarounds for non-residential zones: Shall be designed to accommodate the types of vehicles using the street, alley, or easement. Maximum longitudinal slope permitted for a cul-de-sac or turnaround is 8%.

Alley turns and turnarounds: Turnarounds are required at alley dead ends when the connecting street is an arterial. Figure 4-26: Alley and Easement Turnarounds and Figure 4-25: Cul-de-sacs illustrate alley turns that are approved by the SDOT Director for SF, L1, and L2 zones. All other zones will need individual review. The turn shall be designed to accommodate the types of vehicles using the alley.  Alternate designs may be proposed, and are subject to approval by SDOT. 

The Fire Department may require additional criteria for cul-de-sacs or turnarounds and alley turns or turnarounds when needed for adequate fire access.
continue to section 4.24 »   
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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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