Green, grey or green-grey? Decoding infrastructure integration and implementation for residential street retrofits

Abstract

New-world countries are often characterized by large areas of sprawling post-war suburban development. The streets of these suburbs are often criticized for being unattractive transport corridors that prioritize cars at the cost of the pedestrian environment and ecological health of their neighbourhoods. Green infrastructure (LID) street retrofits, as well as grey infrastructure-dominated traffic calming schemes have been used as partial solutions to the adverse effects of post-war street design. There is, however, a lack of implementation of these measures, along with some confusion as to what is defined as green and grey infrastructure at the street scale. The level to which these schemes are integrated with one another is also unclear.

This paper is based on an international English-language systematic review of academic peer-reviewed literature of built infrastructure elements within residential street settings. The review reports on a body of evidence-based literature, discussing the definitions of green and grey infrastructure at the street scale; along with the barriers and enablers to the implementation of green and grey infrastructure, and the level to which the two are integrated. Barriers and enablers to the successful design and implementation of green and grey infrastructure in residential streets are also investigated.

The physical components of the various infrastructure elements were used to categorize them in order to clearly define the terms green and grey infrastructure within streets. Evidence suggests that there are two ways in which integration of green and grey infrastructure occurs, however only a third of the papers report on green and grey infrastructure integration. Results also show that cost, spatial constraints and resident perception are the most common barriers to the implementation of green and grey infrastructure retrofits in residential streets. Ways to utilize the known barriers and enablers, along with design considerations, are discussed.

The findings presented in this thesis are aimed to provide academics and practitioners with an important series of considerations to help influence the design of street retrofits that achieve a multiple number of social and ecological benefits within a residential setting; in order to help address the adverse social and ecological effects of urbanization and unsustainable post-war development patterns.