Memorandum to Commission

Subject:       Supplemental Information On New Thinking In Residential Street Design

Date: October 1, 2004

Staff:            Linda M. Finger, Planning Director

When considering changes that could be beneficial to residential street design, it is important to not endorse one concept, such as narrow streets or a return to a grid pattern of streets, before fully investigating the options available. Over the last decade, professional organizations such as Urban Land Institute, Institute for Transportation Engineers, the Local Government Commission, and the American Planning Association have been studying how neighborhood design and development can evolve to address the challenge inherent in New Urbanism and SmartGrowth development, which is to return to the basic building block of town development, cohesive neighborhoods.  Professional engineers, architects, landscape architects and planners are discussing how to change the design components of neighborhoods to respond to this challenge. Many of these concepts involve the rethinking of how residential streets are designed.  Although narrow street design or linear grid designs have received much attention of late, there is another concept I would like the commission to consider.

Residential street design is evolving in other countries in a non-linear patter. It has developed out of a concept of shared usage.   The concept of shared streets is simple – “to integrate pedestrian and vehicular movement on one shared surface.”  This concept reverses the typical priority system given to street design in America. In Michael Southworth and Eran Ben-Joseph’s book, Streets and the shaping of Towns and Cities, the design characteristics of shared streets is explained as an approach where the “street has first and foremost the functions of a residence, a playground, and a meeting area.  It has the additional functions of carrying access traffic and providing parking spaces, but is not designed for intentional through traffic.”  Design characteristics that have evolved as typical of shared streets [based on their existing form in other countries], are described as:

o it is a residential, public space

o through traffic is discouraged

o paved space is shared by pedestrians and cars with pedestrians having the priority

o walking and parking are allowed everywhere

o the street form can be a single street, a loop or square, or a combination of streets

o entrances are clearly marked

o there are no conventional, straight stretches of streets with raised curves and sidewalks are not clearly demarked from the vehicular pavement surface [Where curbs are needed for drainage, the same paving material is used to cover the entire area.]

o car speeds and movement are restricted by physical barriers [deviations, bends and undulations]

o residents have automobile access to the dwelling fronts

o there are street furnishings and extensive landscaping

The authors indicate the intent of no curbs and lack of a separate sidewalk has a powerful effect on drivers. “Without the familiar two-curb lines and an asphalt roadway, drivers tend to slow down.”  In some designs parking spaces on streets are clearly defined, in others the use of physical elements such as planting beds, street furniture, and trees are used to define the spaces where cars can fit.  Visually, the street is perceived as one coherent space, and the introduction of the other physical elements control the driver’s conduct in moving along the street or in parking.  In 1977, shared street standards were adopted by the British Dept. of Environment and the Dept. of Transportation and more recently, Japan and Israel have incorporated the “unified street” concept in town design.  Social and safety benefits have been cited for the use of this design concept.  Rather than tying new street design to linear regularity (or grid patterns) it has opened up to designers a freedom to do more spatial patterns that promote clustering of residences.  A cautionary note: Shared streets do not adhere to prescriptive standards, they require a more receptive and flexible design approval procedure.