Can Melbourne depend on infill housing?Posted: November 22, 2011
We know that the inability to increase significantly the supply of dwellings within established suburbs is a key failing of strategic planning in Melbourne. Simply put, there’s not enough housing to make established suburbs affordable for all the people who would like to live in a relatively accessible location.
We also know that activity centres aren’t pulling their weight in the task of increasing supply (see here and here) and that the burden of supply is instead falling on small-scale infill development, much of it dual occupancy projects. So it’s worth looking further at the nature of infill housing.
A study by Monash University’s Thu Phan, Jim Peterson and Shobhit Chandra , Urban infill: the extent and implications in the City of Monash, examined new developments in the municipality over the period 2000-06. They defined infill primarily as projects where two or more new dwellings were constructed on sites formerly occupied by detached houses. A total of 1,483 projects were identified, ranging in size from two dwellings to 178.
The study revealed a number of interesting aspects about this middle suburban municipality.
First, it found new dwelling supply is dominated by small projects. One project built more than 178 dwellings and three built between 40-77 dwellings, however 98% of projects involve just 2-7 seven dwellings (and we can be pretty confident they’re heavily weighted toward the smaller end).
Second, projects are dispersed, not concentrated. As shown in the exhibit, proximity to major trip generators is uncorrelated with location of projects. Just 5% are within 400 metres of a Principal, Major or Specialised activity centre, and only 10% are within 400 metres of a rail station. Moreover, the authors found projects located within 400 metres of an activity centre are smaller on average than those in more distant locations.
Third, developers tend to be opportunistic rather than strategic – they wait for properties to be offered for sale and assess each one on its potential for redevelopment. Thus the geography of infill development is shaped largely by what comes on the market rather than by any sort of deterministic planning policy.
Fourth, the size of lots and the age of the existing house is a more important influence on the location of infill development than proximity to an activity centre or rail station. The average infill site is relatively large (700 to 900 sq m) and the majority of existing dwellings are relatively old i.e. built between 1945 and 1965. Lot sizes close to rail stations are smaller – and hence less amenable to redevelopment – than those further away, probably reflecting the different periods of development.
Thus not only are activity centres failing to expand housing supply in accordance with the precepts of Melbourne 2030, but the great bulk of new housing being built in Monash isn’t located close to activity centres but rather is dispersed (relatively uniformly too judging by the exhibit i.e. non-randomly).The dispersed pattern will worry some, but I don’t see it as a big issue.
One reason I’m reasonably relaxed is because the 400 metre standard is too stringent. Extending the buffer to 800 metres around an activity centre picks up 20% of infill projects and 800 metres around a rail station picks up 34%. That’s a big improvement, although it’s still a minority of projects. Another reason is proximity to public transport (except in the city centre) doesn’t have a big influence on travel behaviour anyway. But most importantly, households that locate in any part of Monash will exhibit more sustainable travel behaviour than they would if they had to locate on the fringe.
To my mind, the key issue arising from the Monash study is that we are heavily reliant on huge numbers of very small infill projects to increase supply in established suburbs. At present, this strategy is delivering a lot of housing but it’s not enough – over half of the net increase in dwelling supply in Melbourne is still located in the outer suburbs.
There seems to be limited scope to crank-up infill supply significantly. Existing residents don’t like their streets being changed by infill housing and Councils, not surprisingly, tend to act in accordance with their constituents wishes. Likewise, there’re few reasons to be optimistic that the supply of dwellings in activity centres will increase significantly.
The nub of it is existing residents don’t see themselves getting a net benefit from redevelopment, at least within a plausible time frame. The two current models – i.e. higher density housing in activity centres and small-scale medium density infill – are only going to make a substantially higher and sustained contribution to supply if existing residents are prepared to accept more pain (or are compensated in some way). These are terribly hard choices politically.
Next time I’ll talk about an alternative approach that might possibly avoid or at least minimise some of these problems.