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What constitutes a corridor?

Identifying the 'green’ and ‘grey’ components of green corridors is an essential part of developing appropriate designs.
Aerial view of city overpass, elevated road junction closeup in Shanghai.
© RMIT Europe and EIT Urban Mobility

Identifying the ‘green’ and ‘grey’ components of green corridors is an essential part of developing appropriate designs.

Categorising and classifying green infrastructure

Green corridors include a range of different types of green infrastructure.

After reviewing academic literature on green infrastructure around the world, Bartesaghi Koc et al. (2017) identified four main categories of green infrastructure:

  1. tree canopy
  2. green open spaces
  3. green roofs
  4. vertical greenery systems (facades/walls).

Green corridors are included in the category of ‘green open spaces’. However, all of this infrastructure can be part of a green corridor when expanding the view to the landscape scale.

The authors (Bartesaghi Koc et al. 2017) also explain that these categories can be further classified based on three principles.

Principle Description Examples
Function Purpose, use and services provided Choice of green infrastructural element (e.g. tree canopy) and desired service, such as shade or rainfall interception.
Structure Morphology Shape of the green infrastructural element dependant on the function, e.g. green canopy on a trellis.
Configuration Spatial arrangements Arrangement of green elements, e.g. clumping of greenery in a pocket park next to a green corridor.

Green and grey components of corridors

Understanding the components of a green corridor supports appropriate planning as explained by Bartesaghi Koc et al. (2017, 31).

A more comprehensive classification of the biotic and abiotic elements forming GI is crucial for the identification of needs, the assessment of conditions and the implementation of planning and design interventions.
  • Biotic refers to the ‘green’ elements of the corridor, or the living things such as trees, shrubs and grasses.
  • Abiotic refers to the ‘grey’ or constructed, physical elements of the corridor, those that are not considered to be living, such as buildings, roads, fences, infrastructure such as electricity poles and wires, and industrial sites.

Boundaries and integration

Often, green corridors don’t have clear boundaries where they start, stop and extend. Instead, the green elements of trees, shrubs and grasses, might be dominant features within the corridor; or they might filter between buildings, roads, and other structures. In addition, the green elements might be incorporated into grey elements, such as green walls and green roofs.

Further, there are elements that may be less obvious, such as underground infrastructure including drainage systems and communication cables, and the quality of the soil.

Academic references (Abstract only free to the public)

In the next step we will take a closer look at the corridor itself. You will be tasked to take a photo so get your camera ready!

© RMIT Europe and EIT Urban Mobility
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Designing a Green Corridor for Clean Air and Comfort

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