Improving road safety is not only reliant on engineering aspects but also on the surrounding landscape, which plays an indispensable role in drivers’ visual perception. As a part of road landscapes, green areas affect road safety by screening or framing views. While vistas could be highlighted in safe spots in order for road users to enjoy their travel, in dangerous scenic points, visual attractions need to be concealed to lessen visual distractions and the risk of accidents. This study aims at optimizing road safety through sustainable landscape design in one of the dangerous Tehran–Dizin road bends to meet both road safety and environmental requirements. In doing so, cone of vision formulas have been applied to calculate measures of green landscape features so as to hide visual distractions and upgrade safety. To design such a green landscape, green resources and their characteristics have been elaborated, and native species have been suggested in plant composition, which can improve the sense of place, enhance the environment, and create a sustainable landscape. The research shows that a cone of vision could functionally be employed to increase the success of a designed green landscape, especially in situations where two-dimensional approaches are not sufficient.

PurposeThe UNESCO recommendation under the historic urban landscapes (HUL) title and Operational Guidelines (OPG) were used to create dynamic protective boundaries to maintain the integrity and authenticity of Isfahan's heritage waterways. Accordingly, by using GIS and Isfahan urban layers, three protective zones were proposed and evaluated; the central zone, the functional zone and the visual zone.Design/methodology/approachHeritage waterways in historic cities are not adequately protected against the negative impacts of urban development, and there is a lack of a dynamic protective system to protect their integrity and authenticity. The problem can be observed in Isfahan, a historic Iranian city, where the boundaries of urban heritage waterways (Madi canals) are usually rigid and arbitrary. This study aims to develop a practicable paradigm for determining protection boundaries for Isfahan's Jolfa Madi, an urban heritage waterway.FindingsCompared to the current protective boundaries, the authors found that proposed protective boundaries create a greater amount of protection space, which makes a strong connection among the ecological, historical and socio-economic characteristics of the urban context. Furthermore, the protective zones based on the HUL approach give Isfahan's urban planning policy the opportunity to consider participatory tools, financial tools and regulatory systems.Originality/valueMany studies have emphasized a fixed-width buffer or an arbitrary distance from the urban waterway's axis (urban heritage) or its banks. Although these protections include technical conservation or setting restrictions on the adjacent buildings and blocks, studying crucial concepts such as urban dynamic, urban heritage context and producing a particular technique for protected boundaries has not been investigated. In this article three dynamic boundaries are delineated with various functions in order to provide urban heritage with dynamic preservation and sustainable development for the historic urban landscapes.

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