scholarly journals Off the Grid... and Back Again? The Recent Evolution of American Street Network Planning and Design

2020 ◽  
Author(s):  
Geoff Boeing
Keyword(s):  
Urban Form ◽  
Design Patterns ◽  
Open Data ◽  
Urban Spatial Structure ◽  
Street Network ◽  
Street Networks ◽  
Planning And Design ◽  
Orientation Order ◽  
Established Relationship ◽  
Intersection Density

This morphological study identifies and measures recent nationwide trends in American street network design. Historically, orthogonal street grids provided the interconnectivity and density that researchers identify as important factors for reducing vehicular travel and emissions and increasing road safety and physical activity. During the 20th century, griddedness declined in planning practice alongside declines in urban form compactness, density, and connectivity as urbanization sprawled around automobile dependence. But less is known about comprehensive empirical trends across US neighborhoods, especially in recent years. This study uses public and open data to examine tract-level street networks across the entire US. It develops theoretical and measurement frameworks for a quality of street networks defined here as griddedness. It measures how griddedness, orientation order, straightness, 4-way intersections, and intersection density declined from 1940 through the 1990s while dead-ends and block lengths increased. However, since 2000, these trends have rebounded, shifting back toward historical design patterns. Yet, despite this rebound, when controlling for topography and built environment factors all decades post-1939 are associated with lower griddedness than pre-1940. Higher griddedness is associated with less car ownership—which itself has a well-established relationship with vehicle kilometers traveled and greenhouse gas emissions—while controlling for density, home and household size, income, jobs proximity, street network grain, and local topography. Interconnected grid-like street networks offer practitioners an important tool for curbing car dependence and emissions. Once established, street patterns determine urban spatial structure for centuries, so proactive planning is essential.

scholarly journals Planarity and Street Network Representation in Urban Form Analysis

2018 ◽  
Author(s):  
Geoff Boeing
Keyword(s):  
Real World ◽  
Travel Behavior ◽  
Urban Form ◽  
Design Patterns ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Two Dimensions ◽  
Street Network ◽  
Form Analysis ◽  
Street Networks

Models of street networks underlie research in urban travel behavior, accessibility, design patterns, and morphology. These models are commonly defined as planar, meaning they can be represented in two dimensions without any underpasses or overpasses. However, real-world urban street networks exist in three-dimensional space and frequently feature grade separation such as bridges and tunnels: planar simplifications can be useful but they also impact the results of real-world street network analysis. This study measures the nonplanarity of drivable and walkable street networks in the centers of 50 cities worldwide, then examines the variation of nonplanarity across a single city. It develops two new indicators - the Spatial Planarity Ratio and the Edge Length Ratio - to measure planarity and describe infrastructure and urbanization. While some street networks are approximately planar, we empirically quantify how planar models can inconsistently but drastically misrepresent intersection density, street lengths, routing, and connectivity.

scholarly journals Automated Street Network Analysis for Urban Planners with OSMnx

2018 ◽  
Author(s):  
Geoff Boeing
Keyword(s):  
Travel Behavior ◽  
Urban Form ◽  
Network Modeling ◽  
Street Network ◽  
Urban Networks ◽  
Street Networks ◽  
Household Travel ◽  
Intersection Density ◽  
Block Sizes ◽  
Free Open Source

Street network modeling has become ubiquitous in urban planning for analyzing transportation infrastructure, household travel behavior, accessibility and social equity, location centrality, walkability, and indicators of the urban fabric including block sizes, intersection density, and connectivity. However, straightforward, scalable tools for professional planners to automatically acquire and analyze detailed street networks have been few and far between. OSMnx offers an easier way. It is a new, free, open-source tool that allows anyone to download walkable, drivable, or bikeable urban networks from OpenStreetMap for any city name, address, or polygon in the world, then automatically analyze and visualize them. OSMnx democratizes these data and methods to help technical and non-technical planners use OpenStreetMap data to model urban form, circulation, accessibility, and resilience.

scholarly journals Planarity and street network representation in urban form analysis

2018 ◽  
Vol 47 (5) ◽  
pp. 855-869 ◽  
Author(s):  
Geoff Boeing
Keyword(s):  
Real World ◽  
Travel Behavior ◽  
Urban Form ◽  
Design Patterns ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Two Dimensions ◽  
Street Network ◽  
Form Analysis ◽  
Street Networks

Models of street networks underlie research in urban travel behavior, accessibility, design patterns, and morphology. These models are commonly defined as planar, meaning they can be represented in two dimensions without any underpasses or overpasses. However, real-world urban street networks exist in three-dimensional space and frequently feature grade separation such as bridges and tunnels: planar simplifications can be useful but they also impact the results of real-world street network analysis. This study measures the nonplanarity of drivable and walkable street networks in the centers of 50 cities worldwide and then examines the variation of nonplanarity across a single city. It develops two new indicators—the Spatial Planarity Ratio and the Edge Length Ratio—to measure planarity and describe infrastructure and urbanization. While some street networks are approximately planar, we empirically quantify how planar models can inconsistently but drastically misrepresent intersection density, street lengths, routing, and connectivity.

scholarly journals Street Network Resilience Put to the Test: The Dramatic Crash of Genoa and Bologna Bridges

2020 ◽  
Vol 12 (11) ◽  
pp. 4706 ◽  
Author(s):  
Valerio Cutini ◽  
Camilla Pezzica
Keyword(s):  
Urban Form ◽  
Real Life ◽  
Design Decision ◽  
Network Resilience ◽  
Urban Resilience ◽  
Street Network ◽  
The Public ◽  
Planning And Design ◽  
Ex Post ◽  
Urban Futures

Various hazards and endemic threats are increasingly looming over cities, leading planners to rely on a rich toolbox of flexible and inclusive planning instruments and methods, capable of dealing with unpredicted events or sudden urban contingencies, when seeking sustainable urban futures. While sustainability-oriented innovative planning approaches are gaining momentum, ways to embed connected concepts in operational planning and design decision support systems have yet to be fully developed and validated. This paper tackles this issue by proposing and testing, in a real-life scenario, a method for the computational analysis of street network resilience, based on Space Syntax theory. The method is suitable to quantify the capacity of urban grids to absorb sudden disturbances and adapt to change, and to offer support for mitigation decisions and their communication to the public. It presents a set of configurational resilience indices, whose reliability is qualitatively assessed considering the ex-ante and ex-post urban configurations generated by two exceptional and dramatic bridge crashes. These events occurred almost simultaneously in two Italian cities with peculiarly similar characteristics. The results confirm the value of the proposal and highlight urban form, and particularly its grid, as a key driver in building urban resilience, together with the self-organisation capacity of local communities.

The Development of Pompeii’s Urban Street Network

2017 ◽  
Author(s):  
Eric E. Poehler
Keyword(s):  
Urban Form ◽  
Formal Analysis ◽  
Street Network ◽  
Urban Street ◽  
Street Networks ◽  
The City ◽  
Present Understanding

Chapter 2 explores the present understanding of Pompeii’s evolution by disassembling the apparent patchwork of grids across the city and reconsiders the presumed awkwardness in their adhesion. To do this, the traditional tools of formal analysis—street alignments and block shapes—are employed with and critiqued by the stratigraphic evidence recovered in the last three decades of excavation below the 79 CE levels. The result is an outline of the development of Pompeii’s urban form as a series of street networks: from the archaic age, through the period of the “hiatus” of the fifth and fourth centuries BCE, to a reorganization of the city’s space so profound that it can genuinely be considered a refoundation, and finally to the adjustments of a refounded city in the Colonial, Augustan, and post-earthquake(s) periods.

scholarly journals Understanding Chinese Urban Form: The Universal Fractal Pattern of Street Networks over 298 Cities

2020 ◽  
Vol 9 (4) ◽  
pp. 192 ◽  
Author(s):  
Ding Ma ◽  
Renzhong Guo ◽  
Ye Zheng ◽  
Zhigang Zhao ◽  
Fangning He ◽  
...  
Keyword(s):  
Urban Form ◽  
Physical Structure ◽  
Urban Morphology ◽  
Street Network ◽  
Urban Street ◽  
Street Networks ◽  
Topological Measures ◽  
Heavy Tailed ◽  
Definition Of ◽  
Almost All

Urban form can be reflected by many city elements, such as streets. A street network serves as the backbone of a city and reflects a city’s physical structure. A street network’s topological measures and statistical distributions have been widely investigated in recent years, but previous studies have seldom characterized the heavy-tailed distribution of street connectivities from a fractal perspective. The long-tail distribution of street connectivities can be fractal under the new, third definition: a set or pattern is fractal if the scaling of far more small things than large ones recurs at least twice. The number of recurred scaling patterns of far more less-connected streets than well-connected ones greatly helps in measuring the scaling hierarchy of a street network. Moreover, it enables us to examine the potential fractality of urban street networks at the national scale. In this connection, the present study aims to contribute to urban morphology in China through the investigation of the ubiquity of fractal cities from the lens of street networks. To do this, we generate hundreds of thousands of natural streets from about 4.5 million street segments over 298 Chinese cities and adopted power-law detection as well as three fractal metrics that emerged from the third definition of fractal. The results show that almost all cities bear a fractal structure in terms of street connectivities. Furthermore, our multiple regression analysis suggests that the fractality of street networks is positively correlated with urban socioeconomic status and negatively correlated with energy consumption. Therefore, the fractal metrics can be a useful supplement to traditional street-network configuration measures such as street lengths.

scholarly journals Exploring transformation of small and medium-sized historical towns in China with network analysis and user-generated open data

2017 ◽  
Author(s):  
Ye Zhang ◽  
Xiangya Xie ◽  
Jie Zhang
Keyword(s):  
Network Analysis ◽  
Urban Form ◽  
Open Data ◽  
Urban Morphology ◽  
Spatial Integration ◽  
Urban Fabric ◽  
Chinese Cities ◽  
Planning And Design ◽  
Built Form ◽  
Urban Activities

Ye ZHANG1, Xiangya XIE2, Jie ZHANG2 1 Department of Architecture, School of Design and Environment, National University of Singapore, 4 Architecture Drive, Singapore 117566 2 School of Architecture, Tsinghua University, Beijing100084, P. R. China E-mail: [email protected]; [email protected]; [email protected]   Keywords (3-5): urban transformation, small and medium-sized historical Chinese cities, big data While an increasing number of research on transformation and conservation of historical areas of major Chinese cities have been witnessed in recent years (e.g. Whitehand et al, 2011; Whitehand et al 2014; Whitehand et al 2016, among many others), endeavours to studying more ordinary and small and medium-sized historical towns in China are rare. In the near future, those historical towns will be confronted with a new wave of developments, given that urbanisation of small and medium-sized cities and towns is high on China’s 13th five-year plan (2016-2020). This will pose a serious challenge to the conservation of their already vulnerable traditional urban fabric. This study aims to develop an accurate description of the transformation of built form, in particular street and block patterns, of the small and medium-sized historical towns, and how this is associated with the change of spatial distribution of urban activities. A total number of 36 towns in Zhejiang province, China are selected as case studies. Transformation of the urban fabric is examined based on cartographical maps of different historical periods using combined methods of urban network analysis and field survey. A large amount of user-generated geo-referenced open data, such as social media reviews, point-of-interest mapping, microblogs and night time illumination maps, are harnessed to produce a detailed description of urban activity patterns, of which the relationships to the transformation of urban form are investigated using multi-variate regression models. The results show how basic built form parameters such as spatial integration, between-ness centrality, block size and block depth can effectively and accurately describe the transformation of the small and medium-sized historical towns and how the formal changes are linked to the geographical shift of different urban activities. In which ways the findings can inform decision making in urban conservation practice to better address the tension between conservation and developments is discussed at the end.References: Whitehand Jeremy WR, Gu Kai, and Whitehand Susan M. (2011). "Fringe belts and socioeconomic change in China."  Environment and Planning B: Planning and Design 38 (1):41-60 Whitehand Jeremy WR, Gu Kai, Conzen Michael P, and Whitehand Susan M. (2014). "The typological process and the morphological period: a cross-cultural assessment."  Environment and Planning B: Planning and Design 41 (3):512-533. Whitehand Jeremy WR, Conzen Michael P, and Gu Kai. 2016. "Plan analysis of historical cities: a Sino-European comparison."  Urban Morphology 20 (2):139-158.

scholarly journals A multi-scale analysis of 27,000 urban street networks: Every US city, town, urbanized area, and Zillow neighborhood

2018 ◽  
Vol 47 (4) ◽  
pp. 590-608 ◽  
Author(s):  
Geoff Boeing
Keyword(s):  
Urban Form ◽  
Ad Hoc ◽  
Directed Graphs ◽  
Street Network ◽  
Network Characteristics ◽  
Urban Street ◽  
Multi Scale ◽  
Street Networks ◽  
Urbanized Area ◽  
Data Acquisition And Processing

OpenStreetMap offers a valuable source of worldwide geospatial data useful to urban researchers. This study uses the OSMnx software to automatically download and analyze 27,000 US street networks from OpenStreetMap at metropolitan, municipal, and neighborhood scales—namely, every US city and town, census urbanized area, and Zillow-defined neighborhood. It presents empirical findings on US urban form and street network characteristics, emphasizing measures relevant to graph theory, transportation, urban design, and morphology such as structure, connectedness, density, centrality, and resilience. In the past, street network data acquisition and processing have been challenging and ad hoc. This study illustrates the use of OSMnx and OpenStreetMap to consistently conduct street network analysis with extremely large sample sizes, with clearly defined network definitions and extents for reproducibility, and using nonplanar, directed graphs. These street networks and measures data have been shared in a public repository for other researchers to use.

scholarly journals Methods and Measures for Analyzing Complex Street Networks and Urban Form

2017 ◽  
Author(s):  
Geoff Boeing
Keyword(s):  
Complex Systems ◽  
Urban Design ◽  
Urban Form ◽  
Street Network ◽  
Morphological Complexity ◽  
Qualitative And Quantitative ◽  
Street Networks ◽  
The World ◽  
Transportation Research ◽  
Complexity Theories

Complex systems have been widely studied by social and natural scientists in terms of their dynamics and their structure. Scholars of cities and urban planning have incorporated complexity theories from qualitative and quantitative perspectives. From a structural standpoint, the urban form may be characterized by the morphological complexity of its circulation networks – particularly their density, resilience, centrality, and connectedness. This dissertation unpacks theories of nonlinearity and complex systems, then develops a framework for assessing the complexity of urban form and street networks. It introduces a new tool, OSMnx, to collect street network and other urban form data for anywhere in the world, then analyze and visualize them. Finally, it presents a large empirical study of 27,000 street networks, examining their metric and topological complexity relevant to urban design, transportation research, and the human experience of the built environment.

scholarly journals Exploring Urban Form Through Openstreetmap Data: A Visual Introduction

2020 ◽  
Author(s):  
Geoff Boeing
Keyword(s):  
Big Data ◽  
Built Environment ◽  
Urban Form ◽  
Human Experience ◽  
Geospatial Data ◽  
Data Repository ◽  
Street Networks ◽  
Planning And Design ◽  
The World ◽  
Spatial Big Data

This chapter introduces OpenStreetMap—a crowd-sourced, worldwide mapping project and geospatial data repository—to illustrate its usefulness in quickly and easily analyzing and visualizing planning and design outcomes in the built environment. It demonstrates the OSMnx toolkit for automatically downloading, modeling, analyzing, and visualizing spatial big data from OpenStreetMap. We explore patterns and configurations in street networks and buildings around the world computationally through visualization methods—including figure-ground diagrams and polar histograms—that help compress urban complexity into comprehensible artifacts that reflect the human experience of the built environment. Ubiquitous urban data and computation can open up new urban form analyses from both quantitative and qualitative perspectives.

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