An investigation of the 3-30-300 rule in a Swedish context

Abstract: More than half of the world’s population lives in cities and climate change is already an increasing problem in many cities. Climate smart planning is therefore of extra importance and vegetation is considered the single most versatile component to manage climate changes. Nearby and visible vegetation is also found to have positive effects on the mental health and green spaces can furthermore encourage to physical activity. Few efforts have been made to create comprehensive recommendations for urban greening that includes amount of greenery, distance to green spaces and visible vegetation. This has led to the creation of the 3-30-300 rule which is a comprehensive guideline that aims to create greener and healthier cities. The rule states that everyone should see at least 3 trees from their home, every neighborhood should have at least 30% tree canopy cover, and no one should have more than 300 meters to the nearest public green space. The aim of this study has been to do a broad investigation of the 3-30-300 in rule in a Swedish context, partly through GIS analyses in Gothenburg and partly through interviews with city planners. A new viewshed-based method for investigating visible trees has also been proposed and the accuracy of this method has been investigated. The result from this study shows that it is difficult to fulfill 3-30-300 in the central and industrial areas of the city. The goals of 3 visible trees and 300 meters to a green space is found to be feasible while 30% tree canopy cover is found to be hard. The overall accuracy of the proposed viewshed-based method was good (85%) and can suitably be used to investigate the criterion of 3 visible trees. The city planners are primarily positive to 3-30-300 and highlights that it can strengthen the role of urban greening. There are however some potential challenges that can make it difficult to work with 3-30-300 in the planning sector. These are primarily connected to hard competition, limited legislation about urban greening and low generation of money. The high tree canopy cover goal is also assessed as a challenge and the findings from this study indicate that 2-20-200 is a more realistic guideline in a Swedish context.