Sustainable | Sustaining City Streets • Ken Tamminga and Thomas Knüvener
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Ken Tamminga and Thomas Knüvener
Sustainable | Sustaining City Streets
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On Sustainable|Sustaining City Streets
Ken Tamminga 1,* and Thomas Knüvener 2
Citation: Tamminga, K.; Knüvener, T.
On Sustainable|Sustaining City
Streets. Sustainability 2021,13, 1895.
Received: 31 January 2021
Accepted: 1 February 2021
Published: 10 February 2021
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1Department of Landscape Architecture, The Pennsylvania State University, University Park, PA 16802, USA
2Knüvener Architekturlandschaft, Brüsseler Straße 89-93 D, 50672 Köln, Germany;
City streets have long been the subject and context for research. In this Sustainable |
Sustaining City Streets volume, streets and their vast array of activities are examined by
sustainability scientists and urbanists from many backgrounds. We hope that these papers
promote an understanding of the reciprocal nature of the phenomenon of streets and
their relationships with urban inhabitants. The more we reveal and activate sustainable
approaches to streets, the greater the likelihood that our streets will help sustain life
In a late-1950s issue of Fortune, visionary urbanist Jane Jacobs wrote, “The street works
harder than any other part of downtown. It is the nervous system; it communicates the
ﬂavor, the feel, the sights. It is the major point of transaction and communication. The real
potential is in the street” [
]. A generation of scholarship and professional application on
city streets followed, largely focused on morphology, infrastructure, policy, and program:
the physical forms, spaces and patterns, and related human activities and rules, that
characterized “good” streets. As the new millennium approached, there were broader calls
for multi-disciplinary and evidence-based investigations of the dynamic processes that
streets and urban corridors accommodated—or discouraged, as the case may be.
Meanwhile, the global population lodged in cities continued to expand, with especially
serious challenges in the Global South. In particular, since the mid-20th century, policy-
makers’ abetting of the automobile’s dominance has impacted cities and city life around
the world. By the turn of the century, however, critique of the unsustainable streets-
belong-to-cars paradigm gained momentum, and today cases of more balanced approaches
While diverse in scholarly background and geography, the authors introduced below
are quite uniﬁed in seeing streets for the complex, impactful, and malleable urban phe-
nomena that they are. Each paper shows ‘street smarts’ as it reveals ways to manage and
craft more sustainable street systems. As a whole, this collection offers an interdisciplinary,
multi-methods discussion on:
1. What makes for safe, healthy, efﬁcient, convivial and inclusive city streets.
2. Why streets are vital to the well-being of urban inhabitants.
How scholars and practitioners can collaborate on effective interventions along the
street as key factors in urban sustainability.
This collection features 13 papers on an array of subjects, although there are topical
clusters. The plus-50 authors hail from 23 research organizations and 13 countries. Five of
the six populated continents are represented—only Australia is missing from the list. Streets
and street-based phenomena are investigated in western Europe and the United Kingdom;
central Africa; east, southeast, and south Asia; and the United States. Almost 20 distinct
disciplines collectively represent the social sciences (psychology, geography, economics,
logistics, development science), engineering (civil, transportation, systems), design and
policy professions (landscape architecture, urban design, city planning, architecture), and
health and physical sciences (epidemiology, environmental toxicology, atmospheric science).
Sustainability 2021,13, 1895. https://doi.org/10.3390/su13041895 https://www.mdpi.com/journal/sustainability
Sustainability 2021,13, 1895
In terms of the spatial scope of the inquiry, ﬁve papers explore sustainability at the scale of
a precinct in a single city; four papers look at multiple sites in a single city; two address a
single entire metropolis; and two are multi-city in scope.
Of course, there are gaps. For example, there is only passing reference to electric-
assisted micro-mobility, which is quickly becoming entrenched in some cities. The shift
toward more sustainable modes of moving people and materials in the city calls for timely
study and dissemination by a wide cadre of urban scholars. Moreover, no papers deal
substantively with ecology and changing urban climate along the street corridor and the
intriguing opportunities for more robust ecosystem services in the heart of the city.
Eight papers address pedestrian activities and perceptions related to streets and
adjacent land uses, perhaps recognizing that streets are as much vessels for human life
as they are conduits for machines in motion. There is a growing understanding that
active mobility—walking, biking, and a whole range of other muscle-driven or hyper-
efﬁcient modes of urban transport—has positive effects on cities and their citizens. Even
partial liberation from the automobile is resulting in more equitable, healthier, and climate-
responsive shared public spaces and transport modes, along with a variety of green
infrastructure possibilities at local and urban regional levels.
Two papers discuss the use of eye-tracking technology to assess respondents’ reactions
to visual stimuli along the city streetscape. Simpson, Thwaites, and Freeth blend environ-
mental psychology and landscape architecture methodologies in using mobile eye-tracking
glasses to gauge pedestrians’ visual engagement with street edges in Shefﬁeld, UK.
Kim and Park, in a contrasting research context, employ eye-tracking within a virtual
street-view environment to determine respondents’ ﬁxation on signboards as a way of
informing municipal regulation of street-based advertising in Seoul, Korea. Both papers
show the efﬁcacy of eye-tracking in documenting visual interactions on the street. Further,
both produce tangible results that could help guide policy and design seeking to improve
pedestrian experiences within the street canyon.
Perovi´c and Šestovi´c address socio-spatial sustainability in the southeast European
city of Podgorica, the capital of Montenegro. Through theoretical and case study analyses,
they afﬁrm the role of a traditional public open space in helping bolster social identity,
and their design guidelines make a case for shaping human-scale spaces that enhance
socialization and personal well-being.
Wakil et al. address sensory engagement along the streetscapes of Lahore, Pakistan.
They test a novel methodology for the systematic development of a visual pollution
assessment tool for streetscapes. Their expert-based tool teases out consensus on the char-
acteristics of various visual pollution objects, as applied to a series of street-based
The focus on pedestrian accommodation on the street continues with the paper by
Campisi et al. Using a multi-criteria analytical hierarchy process analysis, the authors
evaluate walkability in busy pedestrian areas of Rijeka, Croatia. Although their street-side
surveys were administered pre-COVID-19, they make a solid case for pedestrian behavior
analyses to inform tactical planning that enhances walker mobility while promoting social
distancing and air quality.
Rodriguez-Valencia and Ortiz-Ramirez examine green infrastructure trends on streets
in three American cities: Portland, Seattle, and Philadelphia. Using a qualitative case
study methodology grounded in multi-agent interviews, documentary analyses, and site
observations, they trace the evolution of traditional street design approaches and document
emerging green street design protocols that focus on sustainable stormwater management
in tight urban spaces.
Im’s paper also explores the theme of urban green streets, this time by examining
select civic green street manuals and constructed stormwater-oriented streetscape projects
in select American cities. The author ’s collation of green street beneﬁts results in a proposed
design typology that is then afﬁrmed through multi-expert review.
Lee and Kim address the hazards of walking along the narrow “organically shared”
streets of the dense residential core of Seoul, South Korea. They investigate the effective-
Sustainability 2021,13, 1895
ness of the city’s pedestrian priority street (PPS) strategy for shared space using on-site
videography and a questionnaire survey to assess perceptions of trafﬁc safety along local
streets. Their ﬁndings should prove useful for informing government ofﬁcials and residents
about the value of PPS design protocols.
Tchinda and Kim examine fear of crime in public urban spaces in Yaoundé, the central
African capital of Cameroon. They conduct street corner sampling of pedestrians’ fear of
crime perceptions at ﬁve key street intersections. Survey results are then referenced to
spatial data acquired through drone aerial photography of real-time pedestrian density.
Their work conﬁrms the hypothesis that, in the case of Yaoundé, fear of crime rates rise as
street-side congestion increases.
Lim et al. also address street crime, this time in Kuala Lumpur, Malaysia. Based on
data gleaned from a large survey questionnaire of street-based respondents in the high-
crime Dang Wangi commercial district, the authors conclude that the “Safe City Program
works only when a combination of initiatives from the perspectives of guardians, victims,
and offenders are integrated well.”
The consideration of social factors and civil incivilities on and around city streets is
broadened by Marzbali, Saﬁzadeh, Tilaki, and Abdullah’s contribution. Applying social
disorganization theory to a neighborhood in Penang, Malaysia, they suggest, among other
things, that the human–place bond may lessen the impacts of incivilities on residents’ health
in city neighborhoods. They conclude by discussing practical implications for enhancing
place attachment and social identiﬁcation.
Jia, Ma, and Hu are the sole team that address a complex public transportation system,
in this case in the Chinese city of Xi’an. Their experimental study leverages complex
network theory to investigate the topological properties of Xi’an’s busing network, and
then proposes an optimization model based on betweenness centrality and policy guidance.
Finally, Tönisson et al. present the most transdisciplinary paper of the collection,
with physical, health, and social scientists collaborating as a choreographed unit. Their
mixed-methods approach analyzes quantitative and qualitative data to propose mitigation
strategies for black carbon emissions afﬂicting the streets of Manila, Philippines.
If there is a meta-concept that holds this compendium together, it is the street’s
chameleon-like capacity to simultaneously accommodate ﬂows of life, material, and energy,
while also providing spatial volumes and edges along which urban placefulness, civil
society, and metro-scale economies may develop.
Indeed, during the COVID-19 era, city streets have taken on renewed meaning as
public places of camaraderie, protest, and other forms of expression. The pandemic has also
heightened our collective appreciation of the basic role of streets in the deceptively simple
task of hosting safe and agreeable passage from point A to point B. The street’s dramatic
interplay of infrastructure, environment and humans in motion call for new collaborations—
including fuller engagement with city inhabitants. As these papers suggest, the time is ripe
for city leaders, scholars, planners, and residents to rethink the street as a key driver of
sustainable urban futures.
To conclude, we would like to thank our author colleagues for contributing to this
Special Issue, as it indicates a step forward in the understanding of sustainable streets and
street systems. We also extend our sincere appreciation to peer reviewers. This volume
would not have been possible without their rigorous critique and generous insight during
the manuscript review process. Finally, we express gratitude to the MDPI Sustainability
Editorial Ofﬁce for their enthusiasm and support throughout the process.
Funding: This research received no external funding.
Conﬂicts of Interest: The authors declare no conﬂict of interest.
Jacobs, J. Downtown Is for People (Fortune, 1958). Reprinted in Fortune Classic 2011. Available online: https://fortune.com/2011
/09/18/downtown-Is-for-people-fortune-classic-1958/ (accessed on 10 January 2021).
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