Graphics header for Chapter 8: Streetside Design Guidelines with images of sidewalks, pedestrians and schematics behind the text

Purpose

This chapter provides principles and guidance for the design of a thoroughfare's streetside and the specific elements that comprise the streetside. It addresses how the design of the streetside varies with changes in context. The guidance in this chapter is used in conjunction with the guidance for the other two thoroughfare components葉he traveled way (Chapter 9) and intersections (Chapter 10).

Objectives

This chapter:

1. Defines and discusses four distinct zones that comprise the streetside: edge, furnishings, throughway and frontage;

2. Describes the uses and activities that are typically accommodated within the streetside in urban areas;

3. Describes fundamental design principles of the streetside as they relate to intersection sight distance, speed and clear zones and lateral clearance;

4. Describes the role and placement of streetside facilities, public spaces and public art; and

5. Provides principles, considerations and design guidance for streetside width and functional requirements.

Introduction

The streetside is the portion of the thoroughfare that accommodates nonvehicular activity謡alking as well as the business and social activities熔f the street. It extends from the face of the buildings or edge of the private property to the face of the curb. A well-designed streetside is important to the thoroughfare's function as a "public place." Thoroughfares are the most extensively used civic spaces or in our communities.

Streetside Zones and Buffering

This chapter addresses the design of sidewalks and the buffers between sidewalks, moving traffic, parking and/or other traveled-way elements. The streetside consists of the following four distinct functional zones:

1. Edge zone葉he area between the face of curb and the furnishing zone that provides the minimum necessary separation between objects and activities in the streetside and vehicles in the traveled way;

2. Furnishings zone葉he area of the streetside that provides a buffer between pedestrians and vehicles, which contains landscaping, public street furniture, transit stops, public signage, utilities and so forth;

3. Throughway zone葉he walking zone that must remain clear, both horizontally and vertically, for the movement of pedestrians. The Americans with Disabilities Act (ADA) establishes a minimum width for the throughway zone; and

4. Frontage zone葉he distance between the throughway and the building front or private property line that is used to buffer pedestrians from window shoppers, appurtenances and doorways. It contains private street furniture, private signage, merchandise displays and so forth and can also be used for street cafes. This zone is sometimes referred to as the "shy" zone.

Figure 8.1 illustrates the four zones using the example of a streetside in a commercial area. Guidance is provided for each of these zones, with the width varying in relation to thoroughfare type and function, context zone and specific land use characteristics.

Urban Design Elements

The streetside can contain a variety of urban design elements, ranging from large-scale elements such as plazas, seating areas, transit stops and other public spaces to the details of street furniture, street trees, public art and materials used for constructing sidewalks, walls and so forth.

Diagram depicting streetside zones. It includes an edge zone, furnishings zone, throughway zone and frontage zone.

Figure 8.1 Streetside zones. Source: Concept by Community, Design + Architecture, illustration by Digital Media Productions.

 

Technical Considerations

There is a broad range of technical and engineering considerations that need to be coordinated with the design of the streetside, including the requirements of Americans with Disabilities Act Accessibility Guidelines (ADAAG) and Public Rights-of-Way Accessibility Guidelines (PROWAG) (www.access-board.gov/), need for utilities (including lighting for both the traveled way and streetside), provision of signage for traffic and pedestrians and evaluation of multimodal accessibility. This chapter provides guidance for how these technical issues can be addressed in coordination with the other elements of urban thoroughfares.

The Urban Streetside: Uses and Activities

The basic functions of the streetside in any context are the accommodation of pedestrians, access to adjoining buildings and properties and the provision of clear zones and space for utilities and other streetside appurtenances. In urban contexts these basic functions are shared with the activities generated by the adjacent land use and general civic functions, which can include aesthetics (such as street trees and public art), sidewalk cafes, plazas and seating areas, transit amenities (such as benches, shelters, trash receptacles and waiting areas), merchandise display and occasional public activities (such as farmers' markets or art shows).

Streetside functions vary by context zone and predominant ground floor land use. The width of certain elements of the streetside (for example, the furnishings zone functions as a traffic buffer) will vary by thoroughfare type depending on the existence or lack of on-street parking and the speed and volume of vehicular traffic on the thoroughfare. Variations in the width of the streetside are addressed in the design guidelines in the section on streetside width and functional requirements.

Design Principles

Safety

When designing the streetside, the practitioner is concerned about the safety of all users of the thoroughfare. Streetside safety concerns in urban contexts are different than those in rural contexts, where speeds are higher and most travel is by vehicle. In designing the streetside for traditional walkable urban areas, the practitioner is concerned about the safety of a wider range of users, including pedestrians on the sidewalk, motorists, motorcyclists and bicyclists using the traveled way. The practitioner should consider the context of the thoroughfare, including competing demands within limited right of way and time when the space may be needed.

Streetside safety in urban areas is achieved by separating modes of different speeds and vulnerabilities to the extent possible by both space and time (bicyclists from pedestrians and pedestrians from vehicles), informing all users of the presence and mix of travel modes and through provision of adequate sight distance. The difficulty for the practitioner lies in developing solutions to resolve the inherent conflicts where modes of travel cross paths. Design guidelines for improving pedestrian safety at intersections are discussed in Chapter 10.

Streetside safety for the users of the traveled way in traditional urban areas focuses on meeting user expectations, providing uniform and predictable designs and traffic control, removing clearly hazardous streetside obstacles and establishing an appropriate target speed, which in turn controls the speed-related geometric design elements of the thoroughfare. The practitioner should be familiar with the concepts and guidance provided in AASHTO's Roadside Design Guide (2002).

Relationship of Speed to Streetside Design

A person's decision to walk is influenced by many factors, including distance, perceived safety and comfort, convenience and visual interest of the route (AASHTO 2004b). In the streetside, pedestrians feel exposed and vulnerable when walking directly adjacent to a high-speed travel lane. Vehicle noise, exhaust and the sensation of passing vehicles reduce pedestrian comfort. Factors that improve pedestrian comfort include a separation from moving traffic and a reduction in speed. In walkable urban environments, a buffer zone that improves pedestrian comfort can be achieved with the width of the edge and furnishings zones, landscaping and on-street parking.

Clear Zones

The application of a clear zone is most critical on high-speed roadways and is usually not implemented on low-speed urban thoroughfares with right-of-way constraints. In many cases the hazard of streetside obstacles is substantially less in urban areas because of lower speeds or parked vehicles.

Public Space

Civic and community functions on the streetside may require additional space to complement adjacent civic or retail land uses or to accommodate the high pedestrian flows of adjacent uses or transit facilities. Public spaces in the streetside are often used for these functions and are an important complement to the thoroughfare as a public place. Public spaces include public plazas, squares, outdoor dining, transit stops and open spaces. Transit stops and some plazas are generally within the streetside. Design considerations should account for the context of the public space within the thoroughfare and the surrounding land use context. Public spaces should be designed to serve functions that enhance the surrounding context, such as public gatherings, special events, farmers' markets, quiet contemplation, lunch time breaks and so forth (Figure 8.2). General principles for the design of public spaces include the following:

Placement of Streetside Facilities

Following the division of the streetside into edge, furnishings, throughway and frontage zones, the placement of streetside facilities (such as kiosks and retail stands, trash receptacles, water fountains, re-strooms, public art and small ancillary structures) should occur in the furnishings and frontage zones as well as in curb extensions. In no case should the placement of features reduce the width of the clear pedestrian throughway to less than 5 feet or reduce vertical clearance below 80 inches. All placements should be compliant with the most recent U.S. Access Board and PROWAG requirements and FHWA PROWAAC guidelines: Special Report: Accessible Public Rights-of-Way: Planning and Designing for Alterations.

Photos of retail/dining/shops areas - Public space adjacent to the pedestrian realm should relate to the activities on the thoroughfare

Figure 8.2 Public space adjacent to the pedestrian realm should relate to the activities on the thoroughfare. Source: Kimley-Horn and Associates, Inc.

 

Other considerations regarding streetside facilities are as follows:

1. Place facilities in locations where their use will produce pedestrian activity levels similar to a main street or where an activity focus is desired. Features such as public art should be located in highly visible areas, including the center islands of low-speed roundabouts (ensuring sight triangles are maintained and placement does not constitute a streetside hazard).

2. Select the type, design and materials of street-side facilities to reflect the local character of the context and streetside. This will maximize the facility's contribution to creating a sense of community identity.

3. Coordinate design elements (street furniture, light fixtures and poles, tree grates and so forth) to fit into a desired theme or unified style for a given thoroughfare. This can be best achieved through the preparation of a streetscape improvement plan.

4. Streetside facilities are particularly well suited for placement on very wide sidewalks or large curb extensions. Locate facilities at street corners in a manner that maintains clear sight triangles. (For more information, review the discussions on sight triangles and curb extensions in Chapter 10.)

5. Consider vehicle overhangs and door swings of parked vehicles.

6. Facilities should never obstruct the clear pedestrian throughway, curb ramps, or any accessible element of the streetside.

7. Place vertical elements so they provide the required lateral clearance to the face of the curb and satisfactory shoulder clearance from the clear pedestrian throughway zone.

Photo showing an image of public art in the walking route in front of a building. Public art adds interest to a walking route.

Figure 8.3 Public art adds interest to a walking route. Source: Kimley-Horn and Associates, Inc.

Context Zones

The placement of streetside facilities should be focused in urban center (C-5) or urban core (C-6) context zones with predominantly retail- and entertainment-related ground floor uses with a main street level of pedestrian activity. The need for and benefits from facilities such as kiosks, restrooms, or small-scale retail stands is typically highest in C-5 and C-6 zones.

Facilities in the general urban (C-4) or suburban (C-3) context zones should be located at nodes of increased intensity of ground floor retail and entertainment uses that produce high levels of pedestrian activity. The provision of facilities at public transit transfer centers should be considered in all context zones.

Public Art

Pedestrian improvements create an opportunity to implement public art (Figure 8.3). On a large scale, public art has the ability to identify a district or contribute to a design theme. It can be an effective means of encouraging pedestrian travel by adding interest to the route and creating community identity. The redesign of thoroughfares creates opportunities for the implementation of public art as part of an urban design or streetscape plan. This includes, but is not limited to artistically designed paving; design of furnishings, light fixtures, railings, or low walls; and sculptural objects, murals or other surface treatments. Placement of public art and monuments should not obstruct the driver's view of traffic control devices, be a distraction, or be located in a manner that could create a streetside hazard to motorists.

Design Guidance

Design guidance for the streetside elements of the thoroughfare is provided in the following sections. Specifically, design guidance is provided for streetside width and functional requirements, pedestrian buffers and edge and furnishings zone elements (trees and parkways, sidewalk crossings of driveways and alleys, utilities, street furniture and landscaping).

Streetside Width and Functional Requirements

Related Thoroughfare Design Elements

Photo of a sidewalk/streetside in front of shops. This is a streetside with well defined zones.

Figure 8.4 A streetside with well defined zones. Source: Community, Design + Architecture.

Background and Purpose

The streetside, including the sidewalk, provides for the mobility of people and is an important social space where people interact and walk together, wait for transit, window shop, access adjoining uses, or have a cup of coffee at a street cafe. The streetside must be wide enough to accommodate movement as well as the important social functions related to the land uses located along the thoroughfare. The width and function of the streetside influence safety and help achieve accessibility. The optimal streetside width varies with the expected streetside activities, character of adjacent land uses and speed and volume of vehicular traffic in the thoroughfare.

General Principles and Considerations

General principles in the selection of appropriate streetside width include the following:

Edge Zone Principles and Considerations

The edge zone, which is sometimes referred to as the "curb zone," is the interface between the traveled way and the furnishing zone and provides an operational offset to:

Streetside Zones

A Avenue, Lake Oswego, OR

A Avenue is classified as a major arterial thoroughfare located in a general urban context zone (C-4) in Lake Oswego's downtown central business district and civic center area. Downtown land uses consist of low to medium density commercial mixed use (office over retail/service) with low to medium density residential located one block from A Avenue. The ground floor uses are primarily commercial with a mix of retail, services and restaurants.

Although the streetside on A Avenue is narrow, it contains distinct zones for edge, furnishing, clear through-way and frontage. The edge zone is about 18 inches, allowing an operational clearance for opening car doors.

The furnishings zone (4-5 feet) contains street trees in wells with decorative grates, light standards, shrubs in moveable planters, seating and a collection of public art.

Underground utilities and vaults are also located in this zone. The clear throughway ranges from 5-8 feet and the frontage zone (about 2-3 feet) contains planters, window shopping areas and seating for outdoor cafes.

Photo from sidebar of Streetside Zones - A Avenue, Lake Oswego, OR. This image is a photo that depicts a commercial/retail area with shops, sidewalk and various furnishings such as shrubs, decorative plants and in some cases even public art. See description in Streetside Zones sidebar text above.Photo from sidebar of Streetside Zones - A Avenue, Lake Oswego, OR. This image is a photo that depicts a commercial/retail area with shops, sidewalk and various furnishings such as shrubs, decorative plants and in some cases even public art. See description in Streetside Zones sidebar text above.Photo from sidebar of Streetside Zones - A Avenue, Lake Oswego, OR. This image is a photo that depicts a commercial/retail area with shops, sidewalk and various furnishings such as shrubs, decorative plants and in some cases even public art. See description in Streetside Zones sidebar text above.

Other principles and considerations include:

Photo of pedestriam throughway with bus stop, trees and other furnishings. Utility poles and other fixtures should not interfere with the pedestrian throughway.

Figure 8.5 Utility poles and other fixtures should not interfere with the pedestrian throughway. This example shows a bus shelter and other street furniture properly located in the furnishings zone. Source: Kimley-Horn and Associates, Inc.

Furnishings Zone Principles and Considerations

The furnishings zone is the key buffer component between the active pedestrian walking area (throughway zone) and the thoroughfare traveled way. Principles and considerations concerning furnishings zones include the following:

Throughway Zone Principles and Considerations

Principles and considerations concerning throughway zones include the following:

Frontage Zone Principles and Considerations

The frontage zone is the area adjacent to the property line that may be defined by a building facade, landscaping, fence, or screened parking area. Principles and considerations concerning frontage zones include the following:

Table 8.1 Recommended Streetside Zone Dimensions

  Sidewalk Zone [1] C-6 and C-5 C-4 w/ Predominantly Commercial Ground Floor Use C-4 w/ Predominantly Residential Frontage C-3 w/ Predominantly Commercial Ground Floor Use C-3 w/ Predominantly Residential Frontage
Boulevard Edge 1.5 feet 2.5 feet at diagonal parking 1.5 feet 2.5 feet at diagonal parking 1.5 feet 1.5 feet 2.5 feet at diagonal parking 1.5 feet
Furnishings 7 feet (trees in tree wells) 21.5 foot (recommended) 12 foot (constrained) 7 feet (trees in tree wells) 19 foot (recommended) 12 foot (constrained) 8 feet (landscape strip w/ trees and grasses or groundcovers) 17.5 foot (recommended) 9 foot (constrained) 7 feet (trees in tree wells) 16 foot (recommended) 12 foot (constrained) 8 feet (landscape strip w/ trees and grasses, or groundcovers) 15.5 foot (recommended) 9 foot (constrained)
Throughway 10 feet 8 feet 8 feet 6 feet 6 feet
Frontage 3 feet 2.5 feet 0 feet along lawn and
groundcover
1 foot along low walls, fences and hedges
1.5 feet along facades, tall walls and fences
1.5 feet 0 feet along lawn and
groundcover
1 foot along low walls, fences and hedges
1.5 feet along facades, tall walls and fences
Avenue Edge 1.5 feet 2.5 feet at diagonal parking 1.5 feet 2.5 feet at diagonal parking 1.5 feet 1.5 feet 2.5 feet at diagonal parking 1.5 feet
Furnishings 6 feet (trees in tree wells) 19.5 foot (recommended) 12.0 foot (constrained) 6 feet (trees in tree wells) 16 foot (recommended) 12 foot (constrained) 8 feet (landscape strip w/ trees and grasses or groundcovers) 15.5 foot (recommended) 9 foot (constrained) 6 feet (trees in tree wells) 16 foot (recommended) 12 foot (constrained) 8 feet (landscape strip w/ trees and grasses or groundcovers) 15.5 foot (recommended) 9 foot (constrained)
Throughway 9 feet 6 feet 6 feet 6 feet 6 feet
Frontage 3 feet 2.5 feet 0 feet along lawn and
groundcover
1 foot along low walls, fences and hedges
1.5 feet along facades, tall walls and fences
2.5 feet 0 feet along lawn and
groundcover
1 foot along low walls, fences and hedges
1.5 feet along facades, tall walls and fences
Street Edge 1.5 feet 2.5 feet at diagonal parking 1.5 feet 2.5 feet at diagonal parking 1.5 feet 1.5 feet 2.5 feet at diagonal parking 1.5 feet
Furnishings 6 feet (trees in tree wells) 16 foot (recommended) 12.0 foot (constrained) 6 feet (trees in tree wells) 16 foot (recommended) 12 foot (constrained) 6 feet (landscape strip w/ trees and grasses or groundcovers) 13.5 foot (recommended) 9 foot (constrained) 6 feet (trees in tree wells) 15 foot (recommended) 12 foot (constrained) 5 feet (landscape strip w/ trees and grasses or groundcovers) 12.5 foot (recommended) 9 foot (constrained)
Throughway 6 feet 6 feet 6 feet 6 feet 6 feet
Frontage 2.5 feet 2.5 feet 0 feet along lawn and
groundcover
1 foot along low walls, fences and hedges
1.5 feet along facades, tall walls and fences
1.5 feet 0 feet along lawn and
groundcover
1 foot along low walls, fences and hedges
1.5 feet along facades, tall walls and fences

Notes: Recommended dimensions for the throughway zone may be wider in active commercial areas.

See Table 5.2 in Chapter 5 for discussion of minimum streetside zone widths in constrained conditions.

1 In AASHTO's Guide for the Planning, Design, and Operation of Pedestrian Facilities, the furnishing zone is termed the "buffer" zone, and the frontage zone is termed the "shy distance."

Diagram for Preferred accessible designs for driveway and alley crossings. This shows an arrow straight across the driveway, above the slanted gradated entrance.

Diagram for Preferred accessible designs for driveway and alley crossings. This shows an arrow that curves around a gradated driveway entrance, accommodating the sidewalk that is closer to the curb.

Diagram for Preferred accessible designs for driveway and alley crossings. This shows an arrow going straight across a wider sidewalk that has the gradated entrance inside the sidewalk area.

Figure 8.6 Preferred accessible designs for driveway and alley crossings. Source: based on Designing Sidewalks and Trails for Access. Illustration by Digital Media Productions.

Table 4.1 in Chapter 4 includes a discussion of context zones and frontage types.

Driveway Crossing Principles and Considerations

Principles and considerations concerning driveway crossings include the following: Appearance of the sidewalk (scoring pattern or special paving) should be maintained across driveway and alley access points to indicate that, although a vehicle may cross, the area traversed by a vehicle remains part of the pedestrian travel way.

Recommended Practice

Table 8.1 provides an overview of recommended width for each of the streetside zones described in this chapter. The table provides the recommended width of each of the zones by context zone, thoroughfare type and under varying predominant ground floor use conditions. Table 8.1 also provides the total width of the streetside for a constrained condition.

Additional Guidelines

Driveway Crossings

When a driveway is one way only, a maximum width of 14 feet should be considered.

Utilities

Refer to AASHTO's A Guide to Accommodating Utilities Within Highway Right-of-Way (2005) for additional information on the design and placement of utilities.

Street Furniture

Street furniture placed along a sidewalk is an amenity that encourages walking. Street furniture耀uch as public telephones, seating, trash receptacles and drinking fountains用rovides both a functional service to pedestrians and visual detail and interest. Street furniture also conveys to other users of the thoroughfare that pedestrians are likely to be present. Guidelines include the following:

Landscaping

Landscaping is typically located in the furnishings zone of the streetside. Vegetation, especially trees, adds soft textures and bright colors to the concrete and asphalt surfaces of the thoroughfare and thereby increases comfort and distinguishes an area's identity. Landscaping also offers important ecological benefits. Trees are frequently the most visibly significant improvement, if properly selected, planted and maintained. They provide shade from the sun, intercept stormwater and buffer pedestrians from passing vehicle traffic. Guidelines include the following:

Photo of street with sidewalk in front of shops with cars parked out front, parallel to sidewalk near trees that extended into parking lane. Street tree planted in curb extension in parking lane.

Figure 8.7 Street tree planted in curb extension in parking lane. Source: Kimley-Horn and Associates, Inc.

 

Utilities and Street Trees

Both overhead and underground utilities can pose conflicts with street trees.

Mature trees' branches may interfere with overhead wires and lead to "topping" by utility providers. This practice is unattractive and can be detrimental to the tree's branching structure. To avoid this situation, consider under-grounding utility lines or select shorter trees whose branches will remain below the utility lines.

When planning for street tree planting, identify and avoid any underground utilities that could be damaged during the installation process or tree roots.

Plan to "train" newly planted trees in the first years of growth to guide branch development and vertical clearance.

To avoid damage to utilities, sidewalks and pavement, encourage deep roots with use of watering tubes that allow water to seep into the soil below the roots.

Consider "root barriers," underground barriers enclosing roots, where there is potential for root damage.

Photo of roadside depicting A combination of on-street parking, furnishings zone and wide pedestrian throughway provides ample buffer from moving traffic.

Figure 8.8 A combination of on-street parking, furnishings zone and wide pedestrian throughway provides ample buffer from moving traffic. Source: Kimley-Horn and Associates, Inc.

 

Pedestrian Buffer

The buffering of the streetside from vehicle traffic in the traveled way is one of the most important factors in providing pedestrian comfort along urban thoroughfares. The effectiveness of buffers is largely dependent on width (see the section in this chapter on streetside width and functional requirements) and the contributing buffer elements, such as street furniture and landscaping, that can create a visual and sound barrier between the pedestrian and moving traffic (Figure 8.8). On-street parking and edge and furnishings zones combine to provide buffering from traffic. Guidelines include: On-street parking should provide a buffer between pedestrians on the sidewalk and moving traffic; especially in areas with ground floor commercial uses and/or where high volumes of pedestrian activity are expected. Texturing parking lanes or bays with the same material as the sidewalk can visually reduce the width of the roadway when the parking lane is empty;

Justification

Although the recommendations in this chapter are generally consistent with the guidelines contained in the AASHTO Guide for the Planning, Design and Operation of Pedestrian Facilities (2004b), the recommendations for buffer widths in this chapter are wider than those recommended in the AASHTO guide.

Recommendations related to street furniture and landscaping in this chapter are based on recently published best practices, specifically the Santa Clara Valley (California) Transportation Authority's Pedestrian Technical Guidelines (2003), which describes the principles behind the use of street furniture and landscaping to encourage pedestrian activity.

The effect of on-street parking as a pedestrian buffer is generally recognized by practitioners as one factor in creating a comfortable pedestrian environment. Some pedestrian level of service methodologies place significant weight on the presence of on-street parking as a buffer for passing traffic.

Works Cited

American Association of State Highway and Transportation Officials. 1999. Guide for the Development of Bicycle Facilities. Washington, DC: AASHTO.

American Association of State Highway and Transportation Officials. 2002. Roadside Design Guide. Washington, DC: AASHTO.

American Association of State Highway and Transportation Officials. 2004a. Policy on Geometric Design of Streets and Highways, Fifth Edition. Washington, DC: AASHTO.

American Association of State Highway and Transportation Officials. 2004b. Guide for the Planning, Design and Operation of Pedestrian Facilities. Washington, DC: AASHTO.

American Association of State Highway and Transportation Officials. 2004c. A Guide for Achieving Flexibility in Highway Design. Washington, DC: AASHTO.

American Association of State Highway and Transportation Officials. 2005. Accommodating Utilities Within Highway Right-of-Way. Washington, DC: AASHTO.

Santa Clara Valley Transportation Authority. 2003. Pedestrian Technical Guidelines. San Jose, California: Santa Clara Valley Transportation Authority.

U.S. Access Board. 2005. Public Rights-of-Way Accessibility Guide. Public Rights-of-Way Access Advisory Committee (PROWAAC). Special Report: Accessible Public Rights-of-Way: Planning and Designing for Alterations. Washington, DC: U.S. Access Board.

Sources of Additional Information

City of Portland. 1998. Pedestrian Design Guide. Portland, OR: City of Portland, Oregon..

Transect Codeware Company. 2002. Smart Code. Duany Plater-Zyberk & Company. Version 2.6. Miami, FL: Transect Codeware Company.