Suburban Futures, Density and Amenity: Soft Densification and Incremental Planning for Regeneration

R1_1: There needs to be greater clarity about: a) the core concepts, such as what is greyfield and how density is measured;

b) the research questions and the link to research methods;

c) the evidence base, which in places is selective and unclearly presented;

d) how the authors' claims are supported by evidence

The whole introduction has been rewritten. The overly simplistic green/brown/grey trichotomy has been removed and replaced with more nuanced terms.

The aims of the paper are now more explicit, as are the necessary proofs to support our 3 premises.

A methodology section has been introduced to show the flow of the various data used throughout the paper and the particular methods used for each major point. This section gives a clearer flow of what’s going to happen and why the various proofs for each premise is needed.

R1_2: line 38 “Infill” has a particular connotation in many countries of development that increases density by using previously non-built upon land. Here you could also be referring to demolition and rebuild at higher density, or additional stories, or subdivision to increase housing numbers. Greater clarity would be helpful

For clarity we have removed the term ‘infill’ and instead opted for less jargonistic words. Simply stating that urban consolidation policies are in operation, that Australian suburbs are historically planned for very low density, that we will show trends of densification, and that the land use practices need consideration going forward.

R1_3: Line 43 “Greenfield” development can also occur in urban core, or indeed anywhere, it doesn’t specifically denote land beyond the urban area. Need greater clarity regarding how you are using these terms (and why deviating from others use).

Indeed. We have become lazy and far too reliant on these terms. This was a good wake-up call to capture the nuanced aspects of land use planning and not just use simplistic labels.

We have removed this term and instead used peri-urban development.

R1_4: Line 54: “Brownfield land” doesn’t need to be industrial, nor large, nor single lots, nor capable of large-scale redevelopment in the literature – is there a particular Australian definition here? The discussion of “greyfield” has been picked up elsewhere, consider going beyond the Newton ref (e.g. Boyko and Cooper, 2011; Puustinen et al., 2022)

Good point and taken on. See the above comment.

Puustinen et al proved to be incredibly useful in defining the types of densification process. We have used their “role of strategic planning” category to define the difference between our original ‘brownfield/activity centre’ form of development and the original ‘greyfield’ form of development. The latter having little or no strategic focus.

Boyko and Cooper was useful for the new method subsection, particularly the terminology around forms of density measurement.

R1_5: Lines 35-76 The text doesn’t really engage with the housing and planning literature on key terms, but uses references to support the authors’ definitions

See above. We have engaged with the literature to a far greater degree, removed many terms and only used greyfield in its localised context, stating explicitly that it is non-strategic incrementalism and noting the distinction between the US model of commercial strip and mall renewal.

R1_6: Lines 78-89. Greater clarity would be helpful between international agendas (e.g. UN-Habitat) and the workings of the state in Melbourne, at present little evidence is provided to show that there is a top-down impact

The reference to UN agenda has simply been incorporated into the text as part of the literature stating that compactness needs to be through of holistically. Also the workings of the state have been tempered with the workings of the market, council and the host of other issues affecting housing development.

R1_7: Lines 84-88. Is this a form of Transit Oriented Development? You make the link later to 20 minute neighbourhoods – consider expanding significantly here. When I read on to section 1.2 I felt the amenity angle and compact city hadn’t been covered sufficiently. Maybe need more on ‘good density’ and normativity?

We have elaborated on good density – particularly the local catch phrase “density done well” and shown the need for walkable destinations to be created alongside the increase in residential densities. Failing which the 15/20 minute neighbourhood strategies will fail. We have also provided a few lines expanding on the 20-minute concept.

R1_8: Lines 193-206 I enjoyed this section, but felt that it needed contextualisation in relation to the permission of urban expansion. How much of the new houses are density increases and how much expansion? For a spatial explanation of density, the table is difficult for anyone unfamiliar with the four cities to understand – maps would be a more effective way of us understanding the relationship between core, inner, outer, peripheral and beyond the city forms of densification. Why these four cities too?

We have also provided maps showing increase proportions for each city

We have also created a simple table of inner-middle-outer to show development rates. For Melbourne, Brisbane, Perth, Sydney and Adeliade. Simply put, and stated in the paper, these are the 5 biggest cities. Brisbane was problematic though, as it’s a huge council, meaning a municipal assessment is irrelevant over those 3 categories, this becomes more so when we move to smaller cities.

R1_9: Lines 210-230 Why use Melbourne as the example? Needs a clearer justification.

Included in the test that Melbourne has lots of urban villages to use for data analysis (to capture a coefficient of sqm of commercial to residential density), as well as huge unwalkable suburbs. So it has juxtaposed context. Also that Melbourne is the only city to have a unit level geospatial record of all development, which allowing us to see redevelopment locations and rates.

R1_10: Lines 230-250 This needs much more detail. How is the redevelopment potential identified? Why do increased house prices lead to increased density? There are plenty of examples where the reverse has been true – are we at a new moment in planning/housing/urban history that leads to densification where land prices increase? How do parcels of land become densified? Which actors are involved and how do they perceive land price changes?

We have addressed a lot of this in the method section, where to talk to the Redevelopment Potential Index, how it’s made, what it means for housing redevelopment  and also reflected on the fact that it’s not going to happen everywhere, as, politically, lots councils in wealthier areas are quite protectionist. We can see this in the new maps showing density increases V sprawl.

R1_11: 260-311 I don’t really understand how this argument fits within the wider narrative of the paper. Amenities are obviously important, but do they differ significantly by scale (can a shop cater for 10-100 homes? How do we know at what point does density result in disamenity etc?) How do new technologies and the rise of home-based service/amenity provision (e.g. shopping) influence the need for service proximity?

We have now included a statement that explicitly states that additional housing without additional services is creating disamenity and also not contributing to a more holistic interpretation of compactness, in that is does little to reduce car dependence. This was largely the point of the paper but must have been skimmed over.

The assessment of average sqm of commercial land use to dwelling population is one of the core elements of the paper, as it shows typical volumes of commercial land over specific densities. And by looking at the constants of “good” areas – i.e. economically functional and walkable, we can show what volume of land-use can be viable as densities increase.

In terms of reduced need for proximity due to online services – good point. We point to this towards the end of section 4 (demand led amenity) but also state that the need for suburban sociality, particularly with working from home, has increased. The need for spaces to allow the same level of social agglomeration in the suburbs as in the CBD is upon us.

R1_12: Lines 313-367 This section is really fascinating, perhaps the highlight of the article. A couple of questions you may want to reflect on: Is planning responsible for all outcomes? What is the responsibility of land owners and developers in defining how space and densification operate?

We have found that planning sets the tone, and the rules of the game at a specific time. But the form of infill really come down to market and landowners. Having been instrumental in the creation of new laws for precinct planning and site assembly, we are seeing little uptake, due largely to the inability of landowners and developers to coordinate, leading to council planning becoming the police that limits negative externalities on abutting sites, but not when we get the same model continually happening across an entire neighbourhood. We are still grappling with the idea of the precinct and the cumulative effects of incrementalism. It might be ok on a few sites, btu when its everywhere you need an overhaul of the mechanisms allowing it  >

R1_13: Lines 433-515 This section is interesting, and raises quote a lot of fine points. However, they aren’t linked to the evidence identified in the article, as such they are largely the authors thoughts rather than evidence-based advances in planning theory.

Yes. This is an applied discussion of ways forward, particularly given the practical aspect of councils lacking human and financial capital to precinct plan everywhere. This part considers the information in the paper to be true – that amenity needs to be involved in density increases. It then suggests practical ways foreword for councils that won’t break the budget and can become ‘incremental planning’

R1_14: Lines 516-563 Some of the conclusions are significant over-reach from the evidence base. For example, you can’t make claims at the Australian level using one case study. Suggest revising in line with the main contribution of the article and the evidence presented.

Good point. This has been tempered significantly. Redevelopment will not occur everywhere – as least not in our lifetime. Conservative planning, heritage, prestige value, lot size and market pressures have all been introduced as delimiters. Also, and based on another reviewer’s comments, we have also shown that much redevelopment is occurring in strategic centres in the middle-ring areas, making for a more balanced article

R2_1: This paper is well structured and argued, and is supported by a body of evidence which is related satisfactorily to the argument

Thanks. And thanks for all of your comments. You were right. It was very one sided and not taking more strategic sites into account

R2_2: The paper raises many useful points including the piecemeal redevelopment of activity centres without proper strategic context; the significant redevelopment of middle ring suburbs; and the importance of amenity in considering urban consolidation policies

R2_3: The main omission in the modes of development selected is the substantial contribution high and medium rise apartment construction has made to Melbourne’s redevelopment pattern, including for middle ring suburbs. The concentration on ‘soft densification’ and ‘grey fields’ densification seems to have resulted in this pattern being downplayed or ignored. Between 2005-21, middle ring high rise apartment construction totalled about two thirds of the massive inner city high rise, and total middle ring apartment and townhouse construction was double that of inner city high rise

Very good point. The aim was to point out the issues and opportunities of ad-hoc development but obviously this needs tempering. We have included information in the framing of the article, presenting data from the pipeline of medium and high density, from the  Melbourne Urban Development Program, that clearly shows the significance of major developments in the middle ring areas. This actually helps better frame the point, as these areas can afford big planning, and the consideration of all aspects of compactness (precinct planning effectively), whereas as-hoc does not; leading to a lost opportunity for better planned future suburbs.

R2_4: The literature review on compact cities is limited, omitting research on the potential for mixed use development near public transport and activity centres, and various approaches to density including models of urban form. Extensive Australian research has been undertaken on such issues well beyond discussions of brownfield infill and ‘grey field’ models

We have taken out most of the greyfields references, or rather reduced their significance, instead noting that there are strategic and no strategic aspects of density increase and that, while the strategic is delivering dwelling in good locations, that our focus in on the non strategic.

R2_5: However, many redevelopment sites are achieving far higher densities than those discussed, particularly in Mixed Use and Commercial 1 zoned locations in many middle ring municipalities. The paper tends to ignore the redevelopment of large areas of middle ring suburbs for high and medium rise apartment construction close to existing services, a feature contradicting the paper’s conclusion that most density increases in established suburbs are occurring in poorly serviced areas (line 435). Again, the Victorian planning system is based primarily on provisions with a substantial discretionary component (such as discretionary policies and the lack of mandatory height controls) contradicting the conclusion to the contrary (line 445).

We believe we have covered off on this throughout; acknowledging that higher densities can be achieved in areas that are planned for it, such as TODS, C1Z, MUZ etc..

The discretionary element has been addressed as stating that, while the planning scheme does have discretionary elements to it (as in PPN60 for Victoria), on the whole, for most incremental development, the rules of the game are established.

R2_6: The recent Victorian government changes to the statutory planning system through VC242 and VC243, including a housing statement and new particular provisions, are expected to fundamentally alter the pattern of suburban development in ways not considered in the paper. These have occurred only recently and should not count against publication but are indicative of a rapidly altering set of rules not fully considered in the paper

Thanks, we were waiting for this when we submitted the paper.

The penultimate paragraph talks to this and how it will lead to more homes in better locations. While we acknowledge the significance of these changes, questions still remain about areas outside of activity centre buffers. Which is what we finish with.

Thanks for all your comments. It made it far more balanced.