Urban Design Principles for Livable Corridors: The Structuring and Restructuring of Arterial Streets for Livability

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Urban Design Principles for Livable
CorridorsThe Structuring and Restructuring of
Arterial Streets for Livability

• Gregory Tung, Principal
• Freedman Tung Bottomley
• Westside Cities
• Livable Boulevards Symposium
• October 6, 2006

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Corridor as a unit the street space between
the frontage buildings and the frontage buildings
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• Westside arterials range in character and
  intensity from conventional low- to medium-
  density strips (or strip segments) with a high
  proportion of automobile-accessed uses (with
  set-back buildings, driveways, and surface
  parking dominating individual site frontages) -

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• - to higher-density corridors of contiguous,
  zero-setback developments with ground-floor
  retail and commercial use akin to main streets
  on arterials.

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• These differing conditions of corridors and/or
  segments represent different stages of urban
  evolution or intensification. Among American
  cities developed primarily in the age of the
  automobile, the Westside has arguably gone the
  furthest and leads the way for better and worse.

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• Historically, investment form (and thus
  development form) on Westside corridors has been
  innovated by developers, architects and builders
  dealing with building sites on private land all
  taking place during the automobile age.

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• Scholars and planner/observers have noted the
  various innovations in Westside arterial building
  and site development form from the early auto age
  prototypes for car-accessed retail and the
  two-level pedestrian scale/auto scale building
  forms of early arterials, to contemporary formats
  of multistory corner strip malls and other
  typological innovations.

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• In nearly all cases, however, the role and
  definition of the street design itself has been
  largely conventional in terms of the wide
  asphalt motorway, edges of curbside parking
  (expendable where traffic growth has forced the
  issue) and a standard (and often too narrow)
  integral curb/gutter/sidewalk.

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• If we think of the corridor as a unit (or perhaps
  a shotgun marriage) between the development type
  and street type, we see a coupling of private
  site maximization (deployment of a repertoire of
  building types, sometimes innovative, but mostly
  from central casting) and a conventional street
  type (occasionally decorated with better jewelry)

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Corridor as a unit the street space between
the frontage buildings and the frontage buildings
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• As long as the intensity level remained below
  certain thresholds (ADT, street width, and lane
  quantities low enough relative to 1 and 2 story
  development of single uses or simple use
  combinations resulting in the arterial not
  feeling overcrowded and conflicted), the
  marriage could work.

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1. CONVENTIONAL ARTERIAL STREET DESIGN
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• But as corridor densities and use complexities
  have increased and have pressured the arterial
  corridor, this marriage is breaking down
  congestion is unpleasant for drivers, and the
  space and place of the street environment is
  neither attractive nor livable, particularly for
  housing.

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• Different relationship models are needed. While
  both partners have changes to make in order to
  save this relationship, the street space
  component of livable boulevard corridors contain
  largely untapped opportunities to achieve much
  more livability and place distinctiveness than
  what might otherwise be thought possible. High
  quality public realm can help to achieve place
  distinctiveness, neighborhood revitalization, and
  vital open space resources to supplant the
  Westsides already heavily-used parks and plazas.

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1. CONVENTIONAL ARTERIAL STREET DESIGN
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1. CONVENTIONAL ARTERIAL STREET DESIGN
Fragmentation of corridor design and operation by
departmental jurisdictions and stakeholder groups
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Roadside zoning is somewhat helpful in thinking
about street design for pedestrians, but is also
potentially cookbook-like in its conceptual
limitations on street design.
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1. CONVENTIONAL ARTERIAL STREET DESIGN
Auto-dominated space
Ped S/W
Ped S/W
L I G H T T O M E D I U M T R A F F I C
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1. CONVENTIONAL ARTERIAL STREET DESIGN
Auto-dominated space
H E A V I E R T R A F F I C
Building architecture armors itself - becomes
less permeable, more inward-focused - in response
to the unpleasant setting
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1. CONVENTIONAL ARTERIAL STREET DESIGN
Auto-dominated space
Sparse street tree planting has limited buffering
effect
H E A V I E R T R A F F I C
Building architecture armors itself - becomes
less permeable, more inward-focused - in response
to unpleasant setting
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2. STREET TYPE MODIFICATION SPATIAL RETROFIT OF
AN EXISTING CONVENTIONAL ARTERIAL STREET DESIGN
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1. CONVENTIONAL ARTERIAL STREET DESIGN
Auto-dominated space
H E A V I E R T R A F F I C
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2. STREET TYPE MODIFICATION SPATIAL RETROFIT OF
AN EXISTING CONVENTIONAL ARTERIAL STREET DESIGN
Auto-dominated space
Ped realm
Ped realm
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Whittier Boulevard in Montebello before
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Whittier Boulevard in Montebello retrofit
concept
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Whittier Boulevard in Montebello retrofit
concept built
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Whittier Boulevard in Montebello retrofit
concept applied to downtown segment, with other
segments receiving different spatial treatments
as part of corridor revitalization
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Second Street Phoenix, AZ
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Adams Street Phoenix, AZ
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Monroe Street Phoenix, AZ
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First Street (former SR 84) Livermore, CA
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Castro Street Mountain View, CA
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3. STREET TYPE ALTERNATIVE MULTIWAY BOULEVARD
ARTERIAL STREET DESIGN
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3. MULTIWAY BOULEVARD ARTERIAL STREET DESIGN
Auto-dominated space
Pedestrian-ized realm
Pedestrian-ized realm
The Multiway Boulevard concept successfully
manages the complexity of mixed mobility uses and
mixed land uses that typically create winners and
losers on arterial street corridors
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Paseo de Gracia, Barcelona
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Paseo de Gracia, Barcelona
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Paseo de Gracia, Barcelona
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Avenue Montaigne, Paris
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Avenue Montaigne, Paris
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Avenue Montaigne, Paris
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Avenue Montaigne, Paris
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Avenue Daumesnil, Paris
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Boulevard DArcole, Toulouse, France
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Ocean Parkway, Brooklyn NY
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Ocean Parkway, Brooklyn NY
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Ocean Parkway, Brooklyn NY
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Octavia Boulevard in San Francisco 1st new blvd
in US since the 1920s
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Palm Canyon Drive (SR 111) Cathedral City, CA
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Palm Canyon Drive (SR 111) Cathedral City, CA
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Selected Corridor Street Design Tools Just as
urban design and urban structure decisions impact
and mutually influence each other at scales
ranging from the district down to the street
space and building site, street design tools or
characteristics are strongly interwoven no one
factor exists in isolation, relative to
livability.
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Corridor Spatial Proportions important but tied
to scale
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12 Proportions
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Also 12 Proportions
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Corridor Landscape Structure
With street design strategies, the larger scale
of arterials demands larger-proportioned
responses to make a dent
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Arterial corridor without significant tree
structure
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Same arterial corridor with boulevard-scale tree
structure 12 years later
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Streetscape regularity vs irregularity spacing
of streetscape verticals and species
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Pseudo-rural tree placement in an urbanized
setting furthers neither rural informality nor
urban civic form it merely contributes to
confusion.
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Utilitarian fixtures that say freeway rather
than livable a missed opportunity
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Boulevard fixtures that can complement a
districts architectural character and work with
both pedestrian and auto scale
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Utilitarian lighting that doesnt say livable
a missed opportunity
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High quality white lighting distinguishes the
special segments and invites people to come after
dark
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• Horizontal Street Design Elements (the floor),
  though important, are a weaker set of design
  elements that should also be used to support
  desired corridor form, investment, and driver
  behavior after Vertical Street Design Elements
  have been well developed. Many standard
  traffic-related components of horizontal street
  design such as pork chop islands, bulb outs
  large curb radii will reinforce auto-oriented
  character to the exclusion of pedestrian scale
  and place character if you do not control their
  geometry and visual appearance.

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Example Bulb-outs a double-edged sword for
pedestrian scale and character
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Where curbside parking exists, the effective
turning radius allows the actual built curb
radius to stay smaller.
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The unintended consequence of a full bulb-out
(both directions) the look of a large,
auto-oriented curb radius.
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Bulbing in one instead of both crosswalk
directions allows for a smaller curb radius.
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The effect of a bulb-outs larger radius should
be considered.
http//www.ci.vancouver.wa.us/transportation/broch
ures/trafficcalming/CurbExt20BulbOut.JPG
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The question to ask at this intersection, Is
bulbing necessary in both directions?
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The use of contrasting roadway paving materials
to visually narrow the vehicular territory
Contrasting parking lane paving maintains the
appearance of constant sidewalk width on wide
arterial Hollywood Boulevard
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Contrasting center turn lane with textured paving
narrows visible roadway width, limits vehicular
use State Highway 114, Barrington, RI
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First Street, Livermore, CA, as State Highway
before streetscape project
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First Street, Livermore, CA after streetscape
State Highway relocated. 2 lanes converted to
angled parking. Paving of parking lanes with
strongly contrasting pedestrian surface materials
transforms the visual width of a former state
highway for a downtown main street segment.
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Median design an often-missed opportunity to
support corridor form and place identity
The visual shapes and cues of amorphous pork
chop islands are auto-oriented and dont have
to be that way.
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For example, the nose of a median need not be
compelled to trace the S-shape of the turn
pocket lane, but instead can have a geometric
(and civic pedestrian) form. Striping and
chatter bars can do the rest.
Chicago, IL
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The physical form of a median is typically
ignored as a means of contributing to corridor
placemaking. It is a missed opportunity.
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Architectural median curbing on a
Denver residential boulevard a quality statement
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Cobble planter curb walls and paving at a Market
Street median in San Francisco
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Berming and multi-textured planting on
arterial median an imitation of a residential
planter strip in too large of a setting. Neither
rural nor city.
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Juanita Village - 98th Ave NE, Kirkland, WA
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Juanita Village - 98th Ave NE, Kirkland
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Juanita Village 98th Ave NE, Kirkland, WA
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An essential factor in livability is buffering
of fronting rooms of buildings from the effects
of fast traffic
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Juanita Village - 98th Ave NE, Kirkland
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Would you want your living room this close and
this exposed to arterial traffic? Will this hold
value over time?
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Juanita Village - 98th Ave NE, Kirkland
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Avenue Daumesnil, Paris
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Dwellings are buffered from fast traffic by 2
rows of trees and slow speed, pedestrian friendly
environment
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Livable Boulevard Corridors

• The Corridor must be treated as a unit
• Bureaucratic and Stakeholder turfs and
  conventional thinking tend to work against this
• The Street Type needs to serve the Development
  Type
• Boulevards can be major contributors to the
  public realm of neighborhoods and districts
• The most critical Livability measures happen
  right at the street/building interface

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