City streets are often undersupplied with trees and green space. However, parking is abundant – both on streets, and in nearby buildings. With a number of trends and policies encouraging alternatives to driving, the time may be ripe for a conversion of redundant parking space to green space.

In this presentation of forthcoming research, we demonstrate how consolidation of parking into off-street garages can free up hectares of space on city streets for urban greenery. We also model the benefits in terms of tree canopy, stormwater treatment and ecological connectivity.


The City of Melbourne has a canopy cover target of 40%, formulated primarily to address the urban heat island effect. However, finding space for tree planting is challenging in highly urbanised areas, so it is important to seek opportunities for reallocation of land to tree planting. A discussion paper recently prepared as part of the city’s transport plan shines a light on the extent of space allocated to parking.

Transport Strategy Discussion Paper – Car Parking

This discussion paper shows that the city has ~23,000 on-street car parking spaces. At the same time, there are almost 200,000 off-street parking spaces, and there is evidence to indicate that a significant portion of of this off-street parking is vacant. For example, residential parking spaces outnumber vehicles owned in the city by 40%. This suggests considerable redundancy; there is real potential for parking to be consolidated to free up space on city streets.

Figure 1 – Parking in Melbourne – an excerpt from a discussion paper prepared for the city’s transport strategy.

On top of this abundance of off-street parking, many trends will reduce our need for parking. The rise of working from home, the construction of bike lines in many cities, the increasing availability of e-mobility and car-share, and the forthcoming emergence of autonomous vehicles all challenge the current transport paradigm.

In forthcoming research, we demonstrate that thousands of existing on-street parking spaces can be consolidated into vacant parking spaces, even if these on-street spaces can only be moved a maximum of 200m (i.e. a short walk) from their existing location. We demonstrate a simple, modular design that could be used to replace redundant on-street spaces with trees, understorey and dining space. We also model these benefits in terms of canopy, and find considerable benefits (20-50ha at maturity). Considerable benefits in terms of water treatment and biodiversity connectivity are also indicated by our modelling.