Designing blue-green infrastructure
Designing Green and Blue Infrastructure
源自：Urban Design International, 2023, 28(3): 169-171.
作者：Glyn Everett, Olalekan Adekola, Jessica Lamond, et al.
Recommended: Miao Xu, School of Architecture and Urban Planning, Chongqing University. [email protected]
Blue-green infrastructure, such as parks, wetlands, ponds, and green roofs, has become one of the key elements of current urban design practice. In the past, the design of blue-green elements, natural and semi-natural spaces, and restorative spaces in cities was limited to the realm of landscape architecture; With the continuous advancement of urbanization and the intensification of the climate crisis, people have begun to pay more and more attention to the planning and construction of blue-green spaces and infrastructure in urban design. There is a growing recognition that blue-green infrastructure plays a key role in mitigating urban density and population growth, regulating urban climate, providing a wide range of ecosystem services, promoting public health and well-being, and improving the quality of the urban environment (air quality, water quality, biodiversity, etc.).
With the theme of "Blue-Green Infrastructure", this special issue contains a total of 5 articles, which carry out multi-dimensional discussions on the practice and cognition of blue-green infrastructure, covering community participation, urban food supply, environmental justice, planning evaluation and green city evaluation, etc., so as to provide new understanding and ideas for exploring a greener and more sustainable urban design. The first paper argues that community engagement is essential for the "right" implementation of blue-green infrastructure and the provision of sustainable solutions, and proposes a framework for community engagement for the planning and development of blue-green infrastructure. The second article introduces the "urban food forest", an urban open landscape and food production model that is emerging around the world. The article discusses and analyzes the design guidelines for multifunctional urban food forests and explores how they can be integrated into public spaces and encourage public participation. The third article introduces the design transformation of important urban green spaces in Warsaw from modernism to the present, and discusses the development of design methods and concepts of green infrastructure under the transformation of policy guidance and planning concepts. The fourth article considers equitable park accessibility as an important goal of environmental justice, and uses a community park in Izmir, Turkey, as an example to conduct an empirical analysis of planning evaluation. The last article analyzes the Green City Evaluation Index for Jordan's urban centers, and studies the study that prioritizes urban land use and green infrastructure construction, aiming to provide a sustainable urban assessment tool for urban centers in developing countries such as Jordan.
Does widening highways reduce congestion?
Do Highway Widenings Reduce Congestion?
源自：Journal of Economic Geography, 2023, 23(4): 871-900. https://doi.org/10.1093/jeg/lbac034
作者:Ioulia V Ossokina, Jos van Ommeren, Henk van Mourik
Recommended: Jing Shen, School of Geography and Planning, Sun Yat-sen University. [email protected]
Shaogu Wang, School of Geography and Planning, Sun Yat-sen University. [email protected]
Highway widening is the main highway construction method in developed countries in recent years, which can improve road traffic efficiency, alleviate traffic congestion, and promote regional economic development. However, the existing studies have paid little attention to the short-term welfare effects of highway widening, especially considering the endogenous and dynamic nature of the widening. Using the Netherlands as an example, this study analyzes the effects of inter-city highway widening on travel time and traffic flow during congested periods, and how these effects change over a six-year period in time, space, and day.
Based on the longitudinal microscopic data of the detector loop of the Dutch highway, the area within 20 km of the widened road section was taken as the analysis unit, and the two-way fixed-effect model and instrumental variable method were used to control the randomness of the widening time and place and other possible endogenous problems, and the dynamic impact of the widening on the travel time and traffic flow was estimated. The study found that widening significantly reduced travel time during congested hours and led to a strong increase in traffic flow. These effects appear immediately after widening and persist for at least 6 years, with significant spatial differences.
In addition, this study further calculates other effects of widening, including time loss during construction, travel time savings after widening, benefits from trip rescheduling, and construction and maintenance costs for widening. The results show that the accumulated welfare benefits in the 6 years after the expansion are very large, which can offset 40% of the investment cost. Widening leads to a slight redistribution of employment and commercial space within a 10-kilometer radius, but the impact on the population is not significant. These findings illustrate the short-term benefits of widening for travelers, and explain why governments are willing to spend money on more roads, even though they know that congestion will not go away in the long run. UPI
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