| 4.2 Street Classifications and Street Types |
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The City of Seattle classifies streets according to different levels of emphasis on motor vehicle movement versus direct access to property. At one end of the hierarchy, a freeway emphasizes traffic movement, while restricting access to adjacent land. At the other end of the hierarchy, a local street provides easy access to adjacent residential, commercial, and industrial land uses. A description of Seattle’s street classifications is located in the Comprehensive Plan and further defined with maps if each classification in the Transportation Strategic Plan. Although street classifications do not change frequently, they are modified periodically. Any changes to traffic classifications are adopted by City Council Ordinance. Please confirm the classification of streets adjacent to a site with a plan review analyst.
Seattle ’s traffic classifications are based on the American Association of State Highway and Transportation Officials (AASHTO) standards that identify major functional classifications for all urbanized areas that have over 50,000 people.
The Traffic Classifications define the arterial network and include Interstate Freeways, Regional, Principal, Minor and Collector Arterial streets, Commercial and Residential Access Streets and Alleys. The arterial network is the “backbone” of the roadway system and accommodates the most trips for all modes. All arterial types require that sidewalks be constructed with new projects.
In addition to the traffic classifications, Seattle’s street classifications define networks of streets citywide that are designed to accommodate freight, transit, pedestrians and bicycles. A classification also exists to define Seattle’s boulevard system. They are as follows:
Major Truck Streets accommodate significant freight movement through the city and to and from major freight traffic generators including Port of Seattle Terminals, inter-modal rail facilities and the regional freeway network. The Major Truck Street network defines critical connections for freight movement throughout the City and these roadways need to maintain the function of, and capacity for truck movements. Major Truck Streets generally carry heavier loads and higher truck volumes.
Transit Classifications define a network of streets throughout the city that accommodate various levels of transit service.
Bicycle Classifications define an on and off street network of bicycle routes throughout the city.
Boulevard Classifications describe the existing system of boulevards, most of which are owned by the Seattle Parks and Recreation (SPR). Traffic is accommodated on every boulevard and design features must be approved by both SDOT and SPR. |
| 4.2.1 Street Types |
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Seattle ’s street classifications (refer to Comp Plan Policies T10-T15 and Transportation Strategic Plan strategies S3-3.5) define how a street should function to support movement of people, goods and services versus access to property. However, street classifications by themselves are not an adequate local planning and design tool. The design of a street--intersections, sidewalks, and transit stops should reflect the adjacent land uses because the type and intensity of the adjacent land use directly influences how the street is used. Street Types are not additional classifications, but provide a more specific definition of the design elements that support the street’s function and its adjacent land use.
Street Classifications and Street Types provide design guidance for anyone doing work in Seattle's street rights-of-way. Refer to the table below, Identifying Street Classifications and Street Types, to assist with identifying the Street Classification and Street Type that applies to a project. Sections 4.2.1a through 4.2.1h provide more information on design features that are compatible with each Street Type.
SDOT will review street designs and operational characteristics to ensure that a reasonable balance is achieved among competing uses. This role is critical in Seattle, where there is typically very limited space within the right-of-way to accommodate the needs of pedestrians, transit, bicyclists, freight, cars, landscaping, utilities, and parking.
Not all streets in Seattle currently have a designated Street Type. Refer to SDOT's Street Types map.
Street Types Definition
(Reprinted from the Transportation Strategic Plan)
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Name of Street Type
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Street Classification
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Adjacent Land Use
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Regional Connector
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Principal Arterial
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Industrial, Commercial, Residential |
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Commercial Connector
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Minor Arterial
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Commercial, Residential |
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Local Connector
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Collector Arterial
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Residential, Institutional
(community service) |
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Main Street
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Arterial—all |
Neighborhood commercial with
a pedestrian designation
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Mixed Use Street
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Arterial—all |
Neighborhood commercial |
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Industrial Access Street
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Arterial—all, non-arterials in commercial areas
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Industrial, Maritime
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Green Street
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Non-arterial in Downtown
Seattle
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Residential
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Neighborhood Green Street
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Non-arterial outside of
Downtown Seattle
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Residential
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Identifying Street Classifications and Street Types
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| 4.2.1a Regional Connector Streets |
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Regional Connector streets are principal arterials that link urban villages to each other and connect to regional destinations outside of the city. Although they must be accessible and attractive to all modes, they are designed to provide city-wide and regional access for transit, cars and truck trips. Regional Connectors also connect designated manufacturing and industrial centers to the local and regional freight network. They move high volumes of traffic through the city and between urban villages.
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Street Design Features
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Character |
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Curb bulbs
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With on-street parking, and in locations with frequent pedestrian crossings, curb bulbs may be appropriate if they are designed to accommodate the turning movements of trucks and transit vehicles.
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Bicycle routes
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Bicycle routes may occur on Regional Connectors if no feasible alternative route exists, Bicycle access on or parallel to Regional Connectors is important as they are often the most direct link between dense residential neighborhoods and employment centers.
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| Truck route signage |
Signage is encouraged that directs trucks to destinations such as Port facilities, inter-modal rail yards, the regional freeway network and to Seattle’s Manufacturing and Industrial Centers.
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Medians
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Use on streets with three or more lanes only. Medians can be continuous. Appropriate in locations where high volumes of pedestrian crossings occur and depending on left-turn movements. Medians are an access management tool and can also accomplish a variety of community goals such as limiting cut-through traffic, and environmental benefits from trees and landscaping. |
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Crossing islands
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Use on streets with three or more lanes only. Typically a crossing tool used at a crossing location not controlled by a traffic signal.
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Sidewalk width
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As wide as possible to accommodate pedestrians once vehicle access needs are addressed. Additional sidewalk width is encouraged in the vicinity of transit zones.
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Driveways
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Minimize the number of driveways that cross the sidewalk to support pedestrian safety and establish a continuous sidewalk.
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Street trees and landscaping
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A planting strip is encouraged to provide safety through separation between pedestrians and moving traffic. They also provide environmental and aesthetic benefits. Trees in transit zones should be located to be compatible with transit passenger loading areas and maintained so as not to interfere with transit vehicle access.
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Street furniture
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Bus shelters are appropriate in transit zones. Wayfinding signs and other street furnishings are appropriate where right-of-way width allows.
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Pedestrian scaled lighting
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Prioritize at pedestrian crossing locations, in transit zones, where there are concerns about personal security, and in where adjacent land uses support pedestrian activity.
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Decorative elements
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Decorative elements (including public art and special paving) may be appropriate if adequate right-of-way width exists and long term maintenance issues are addressed.
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Awnings or other weather protection
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Appropriate in locations where adjacent land uses support high pedestrian volumes, including transit zones.
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Refer to Figure 4-1: Regional Connector Street Type Section
Priority Design Features
• Sidewalks buffered from moving traffic by additional sidewalk width or planting strip
• Pedestrian facilities including weather protection and lighting at transit zones and in locations where adjacent land uses support pedestrian activity
• Bicycle access accommodated if parallel route is not feasible
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| 4.2.1b Commercial Connector Streets |
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Commercial Connector streets are minor arterials that provide connections between commercial areas of the city, such as neighborhood business districts. They also provide local access within urban villages.
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Street Design Features
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Character
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Curb bulb
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Curb bulbs may be appropriate in locations where there is on-street parking.
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Bus bulbs
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Appropriate in locations to support high transit ridership where on-street parking is a lower priority.and reliable transit service.
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On-street parking
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Prioritize short-term visitor and resident parking when adjacent to commercial and residential land uses respectively. On-street parking should be considered after transit service is accommodated, and may be restricted during peak commuter periods.
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Bicycle routes
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Sign and/or stripe bicycle lanes on designated bicycle routes. Prioritize those routes that are the most direct link between dense residential neighborhoods and employment centers.
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Truck route signage
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Signage to assist trucks is appropriate in locations that have key freight destinations such as Port facilities, the regional freeway network and to Seattle’s Manufacturing and Industrial Centers.
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Medians
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Use on streets with three or more lanes only. Medians can be continuous. Appropriate in locations where high volumes of pedestrian crossings occur and depending on left-turn movements. Medians are an access management tool and can also accomplish a variety of community goals such as limiting cut-through traffic, and environmental benefits from trees and landscaping. |
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Crossing islands
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Use on streets with three or more lanes only. Typically a crossing tool used at a crossing location not controlled by a traffic signal.
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Sidewalk width
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As wide as possible to accommodate pedestrians in balance with vehicle access needs. Additional sidewalk width is encouraged in the vicinity of transit zones.
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Street furniture
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Benches, bus shelters, bike parking, and wayfinding are appropriate if the right-of-way is sufficiently wide to accommodate street furniture and still meet the needs for sidewalk width and landscaping.
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Street trees and landscaping
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A planting strip is desirable and provides safety through separation between pedestrians and moving traffic. They also provide environmental and aesthetic benefits. Trees in transit zones should be located to be compatible with transit passenger loading areas and maintained so as not to interfere with transit vehicle access. |
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Driveways
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Minimize the number of driveways that cross the sidewalk to support pedestrian safety and establish a continuous sidewalk.
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Pedestrian scaled lighting
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Prioritize at pedestrian crossing locations, in transit zones, where there are concerns about personal security, and in where adjacent land uses support pedestrian activity.
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Decorative elements
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Decorative elements (including public art and special paving) may be appropriate if adequate right-of-way width exists and long term maintenance issues are addressed
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Awnings or other weather protection
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Appropriate in locations where adjacent land uses support high pedestrian volumes, including transit zones.
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Refer to Figure 4-2: Commercial Connector Street Type Section
Priority Design Features
• Wide sidewalks and planting strip buffer walking area from moving traffic
• Street trees and landscaping
• Bus shelters at transit zones
• Signed and/or striped bicycle lanes on designated bicycle routes
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| 4.2.1c Local Connector Streets |
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Local Connector streets are collector arterials that provide direct connections between pedestrian generators (e.g., residences, transit stops) and destinations (e.g., community centers, schools, neighborhood main streets). They are designed to emphasize walking, bicycling, and access over mobility and tend to be more pedestrian oriented than Commercial Connector Streets.
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Street Design Features
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Character
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Curb bulbs
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Use in locations with on-street parking.
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Bus bulbs
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Appropriate in locations with high transit ridership where on-street parking is a lower priority.
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Medians
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Crossing islands
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Use on streets with three or more lanes only. Typically a crossing tool used at a crossing location not controlled by a traffic signal.
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On-street parking
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Where sufficient right-of-way exists, on-street parking is encouraged and has benefits for residents, business districts and may provide some traffic calming effect. Should only be encouraged where transit service is not a priority.
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Bicycle lanes
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Sign and stripe bicycle lanes on designated bicycle routes.
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Sidewalk width
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Wide sidewalks support pedestrian activity and are a high priority.
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Street furniture
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Benches, bus shelters, bike parking, and wayfinding are appropriate if the right-of-way is sufficiently wide to accommodate street furniture and still meet the needs for sidewalk width and landscaping.
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Street trees and landscaping
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A planting strip is to provide safety through separation between pedestrians and moving traffic. They also provide environmental and aesthetic benefits. Trees in transit zones should be located to be compatible with transit passenger loading areas and maintained so as not to interfere with transit vehicle access.
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Driveways
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Minimize the number of driveways that cross the sidewalk to support pedestrian safety and establish a continuous sidewalk.
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Pedestrian scaled lighting
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Prioritize at pedestrian crossing locations, in transit zones, where there are concerns about personal security, and in where adjacent land uses support pedestrian activity.
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Awnings or other weather protection
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Appropriate in locations where adjacent land uses support high pedestrian volumes, including transit zones.
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Refer to Figure 4-3: Local Connector Street Type Section
Priority Design Features
• Wide sidewalks with planting strips
• Signed and/or striped bicycle lanes on all designated bicycle routes
• Street trees and landscaping
• Traffic calming may be appropriate
• Bus shelters at transit stops
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| 4.2.1d Main Streets |
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Main Streets are arterial streets located within the most pedestrian-oriented sections of neighborhood business districts. These arterial streets and adjacent properties have a “pedestrian designation” in the Seattle Municipal Code that requires new development to have pedestrian-friendly features.
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Street Design Features
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Character
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Curb bulbs
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Use in combination with on-street parking to support pedestrian activity at corners and shorten crossing distances.
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Bus bulbs
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Appropriate in locations with high transit ridership. Impacts to on-street parking should be considered.
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On-street parking
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Appropriate in business districts consistent with the goals of the neighborhood, the City and in locations after transit service is accommodated. When on-street parking exists, it is actively managed for passenger and truck loading, and short-term customer access.
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Bicycle routes
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Stripe and/or sign designated bicycle routes.
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Medians
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Crossing islands
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Use on streets with three or more lanes only. Typically a crossing tool used at a crossing location not controlled by a traffic signal.
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Sidewalks
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Wide sidewalks support pedestrian activity and are a high priority.
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Street trees and landscaping
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Wide planting strip with mature street trees and landscaping significantly enhance the street for pedestrians. Trees in transit zones should be located to be compatible with transit passenger loading areas and maintained so as not to interfere with transit vehicle access.
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Pedestrian scaled lighting
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Pedestrian scaled lighting lights the sidewalk and provide a consistent vertical design element to the streetscape. Prioritize at pedestrian crossing locations, in transit zones, where there are concerns about personal security, and in where adjacent land uses support pedestrian activity.
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Street furniture
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Benches, bus shelters, bicycle parking and signs and maps (wayfinding) are all encouraged to support pedestrian activity and comfort. Consistent design among street furniture elements can enhance the streetscape and should be considered.
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Driveways
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Minimize the number of driveways that cross the sidewalk to support pedestrian safety and establish a continuous sidewalk.
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Awnings and weather protection
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Encouraged, especially in locations where adjacent land uses support high pedestrian volumes, including transit zones.
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Priority Design Features
• Wide sidewalks and planting strip
• Curb bulbs in locations where there is on-street parking
• Street trees and landscaping
• Pedestrian scaled lighting
• Street furniture
• Awnings and weather protection
• Signed and/or striped bicycle lanes on designated bicycle routes
• Bike parking in business districts
• Short-term, on-street parking
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| 4.2.1e Mixed Use Streets |
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Mixed Use Streets are arterials located in neighborhood commercial areas that do not have a pedestrian land use designation. They typically connect to Main Streets and have adjacent land uses that are fairly dense and mixed use. Mixed Use Streets accommodate all modes of travel with particular emphasis on supporting pedestrian, bicycle and transit activity.
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Street Design Features
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Character
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Curb bulbs
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Use in combination with on-street parking to support pedestrian activity at corners, shorten crossing distances and slow speeds for turning vehicles.
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Bus bulbs
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Appropriate in locations with high transit ridership. Impacts to on-street parking should be considered.
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Medians
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Crossing islands
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Use on streets with three or more lanes only. Typically a crossing tool used at a crossing location not controlled by a traffic signal.
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On-street parking
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Appropriate in business districts consistent with the goals of the neighborhood, the City and in locations after transit service is accommodated. When on-street parking exists, it is actively managed for passenger and truck loading, and short-term customer access.
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Bicycle routes
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Stripe and/or sign designated bicycle routes.
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Medians or crossing islands
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Medians or crossing islands are encouraged, where right-of-way width allows, to manage traffic, improve the aesthetics of the right-of-way and improve pedestrian crossing conditions.
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Sidewalks
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Wide sidewalks support pedestrian activity and are a high priority.
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Street trees and landscaping
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Wide planting strip with mature street trees and landscaping significantly enhance the street for pedestrians. . Trees in transit zones should be located to be compatible with transit passenger loading areas and maintained so as not to interfere with transit vehicle access.
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Pedestrian scaled lighting
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Pedestrian scaled lighting lights the sidewalk and provide a consistent vertical design element to the streetscape. Prioritize at pedestrian crossing locations, in transit zones, where there are concerns about personal security, and in where adjacent land uses support pedestrian activity.
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Pedestrian scaled lighting
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Pedestrian scaled lighting lights the sidewalk and provide a consistent vertical design element to the streetscape. Prioritize at pedestrian crossing locations, in transit zones, where there are concerns about personal security, and in where adjacent land uses support pedestrian activity.
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Street furniture
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Benches, bus shelters, bicycle parking and signs and maps (wayfinding) are all encouraged to support pedestrian activity and comfort.
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Driveways
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Minimize the number of driveways that cross the sidewalk to support pedestrian safety and establish a continuous sidewalk.
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Awnings and weather protection
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Encouraged, especially in locations where adjacent land uses support high pedestrian volumes, including transit zones.
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Refer to Figure 4-5: Mixed Use Street Type Section
Priority Design Features
• Wide sidewalks and planting strips
• Curb bulbs in locations where there is on-street parking
• Street trees and landscaping
• Pedestrian scaled lighting
• Awnings and weather protection
• Signed and/or striped bicycle lanes on designated bicycle routes
• Bike parking in business districts
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| 4.2.1f Industrial Access Streets |
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Industrial Access Streets are arterials and non-arterials that are adjacent to industrial and manufacturing land uses. They are designed to accommodate significant volumes of large vehicles such as trucks, trailers, and other delivery vehicles.
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Street Design Features
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Character
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On-street parking
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Load zones in locations to accommodate truck delivery.
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Truck route signage
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Signage is encouraged that directs trucks to destinations such as Port facilities, inter-modal rail yards, the regional freeway network and to Seattle ’s Manufacturing and Industrial Centers.
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Sidewalk width
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Sidewalk width must meet minimum requirements and may be wider if sufficient right-of-way exists once vehicle access needs are addressed. Additional sidewalk width is encouraged in the vicinity of transit zones.
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Street trees and landscaping |
A planting strip with
low landscaping or high branching trees
is encouraged to support freight mobility
and to provide separation between moving
traffic and pedestrians. Tree limbs should
not interfere with truck movements. |
Bicycle lanes |
Parallel facility recommended
to accommodate bicycle connections. |
Refer to Figure 4-6: Industrial Access Street Type Section
Priority Design Features
• Truck route signage
• Load zones to support delivery activities
• Low landscaping or high branching trees in planting strips
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| 4.2.1g Green Streets |
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Green Streets are designated on a number of non-arterial streets within Downtown Seattle. Landscaping, historic character elements, traffic calming, and other unique features distinguish Green Streets from other Street Types. Refer to Chapter 6.2 Green Streets for a complete description of right-of-way improvements on Green Streets.
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Street Design Feature
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Character
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Curb bulbs
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Use in combination with on-street parking to support pedestrian activity at corners, shorten crossing distances and slow speeds for turning vehicles.
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Bus bulbs
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Appropriate in locations with high transit ridership. Impacts to on-street parking should be considered.
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On-street parking
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On-street parking may be appropriate to support short-term customer access, but should be limited to allow for pedestrian facilities.
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Bicycle routes
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Bicycles share the road with motor vehicles on these slow speed, non-arterial streets.
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Sidewalks
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Wide sidewalks support pedestrian activity and are a high priority.
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Street trees and landscaping
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Wide planting strip or double rows of street trees with mature street trees and landscaping enhance the street for pedestrians, while maintaining adequate and comfortable sidewalk width.
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Pedestrian scaled lighting
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Pedestrian scaled lighting that lights the sidewalk and provide a consistent vertical design element to the streetscape.
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Street furniture
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Benches, bus shelters, bicycle parking and signs and maps (wayfinding) are all encouraged to support pedestrian activity and comfort. Consistent design among street furniture elements can enhance the streetscape and should be considered.
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Driveways
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Driveways that cross the sidewalk are not encouraged.
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Awnings or other weather protection
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Appropriate in locations where adjacent land uses support high pedestrian volumes, including transit zones.
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Refer to Figure 4.7: Green Street Type Section
Priority Design Features
• Wide sidewalks and planting strip
• Tight curb radii (and curb bulbs when there is on-street parking)
• Curb bulbs in locations where there is on-street parking
• Street trees and landscaping
• Driveways not encouraged in order to create a continuous sidewalk
• Pedestrian scaled lighting
• Street furniture
• Awnings and weather protection
• Bike route shared with motor vehicles
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| 4.2.1h Neighborhood Green Streets |
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Neighborhood Green Streets may be any non-arterial street outside of Downtown Seattle. Similar to Green Streets, Neighborhood Green Streets emphasize pedestrian facilities, landscaping, historic character elements, traffic calming, and other unique features. Refer to Chapter 6.2 Green Streets for a more complete description of right-of-way improvements on Neighborhood Green Streets.
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Street Design Feature
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Character
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On-street parking
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On-street parking may be appropriate to support short-term customer access, but should be limited to allow for pedestrian facilities.
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Bicycle routes
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Bicycles share the road with motor vehicles on these slow speed, non-arterial streets.
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Sidewalks
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Wide sidewalks or walkways in areas without curbs support pedestrian activity and are a high priority.
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Street trees and landscaping
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Wide planting strip or double rows of street trees with mature street trees and landscaping enhance the street for pedestrians.
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Drainage
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Natural drainage systems are encouraged in creek watersheds. Refer to Chapter 6.4 Natural Drainage Systems for more detail.
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Pedestrian scaled lighting
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Pedestrian scaled lighting that lights the sidewalk and provide a consistent vertical design element to the streetscape.
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Street lighting
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Pedestrian scaled lighting that lights the sidewalk, especially on streets leading to schools, community centers or transit stops.
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Street furniture
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Benches, bus shelters, bicycle parking and signs and maps (wayfinding) are all encouraged to support pedestrian activity and comfort. Consistent design among street furniture elements can enhance the streetscape and should be considered.
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Driveways
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Driveways that cross the sidewalk are not encouraged.
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Awnings or other weather protection
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Appropriate in locations where adjacent land uses support high pedestrian volumes, including transit zones.
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Refer to Figure 4-8: Neighborhood Green Street Type Section—without Curb
Refer to Figure 4-9: Neighborhood Green Street Type Section—with Curb
Priority Design Features
• Walkways and planting strip
• Street trees and landscaping
• Driveways not encouraged in order to create a continuous sidewalk
• Natural drainage encouraged
• Pedestrian scaled lighting
• Street furniture
• Awnings and weather protection
• Bike route shared with motor vehicles
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