A city's health is dependent upon that of the public realm

Brisbane Lord Mayor Campbell Newman's proposal to use the private sector to build and operate new council facilities, such as libraries and pools, deserves serious debate.

This means taking the discussion beyond the confines of financial analysis to consider the social implications of the proposal.

Presumably the idea is not driven by the need to plug any gap in council finances that the tunnel plans may create. This would represent a reactive, and ultimately ineffective, way of planning for municipal social and physical infrastructure.

Australian metropolitan management has been plagued by decades of ad hoc and reactive infrastructure planning and delivery. The consequences of this are especially evident in our urban transport "systems", which are poorly integrated and whose planning and operation are dictated by an increasingly complex array of competing interests.

In Melbourne, the privatisation of public transport has added to system complexity and dysfunctionality - a process that some scholars call "splintering urbanism". It has blurred the focus on what must be the overriding goals of an urban transport system: sustainability, accessibility and equity.

Thankfully, in southeast Queensland things have recently gone the other way. The state's new Translink system, which was strongly supported by the Lord Mayor and Brisbane City Council, represents a major re-integration of public transport services, which has already produced service improvements and higher patronage levels.

Would the entry of the private sector into social infrastructure provision also contribute to splintering urbanism? Very possibly, because the logic of the market is ultimately irreconcilable with many of the broad community interests served by public facilities.

Public infrastructure, and the public domain generally, exists to address important areas of market failure or under-provision, not all of which relate to financial imperatives, such as the pricing and funding of public goods.

Like public transport, our system of municipal social infrastructure - community facilities and spaces - serves a set of overriding public interests. For social infrastructure, these are: service access, social equity, and community solidarity.

The first goal is straightforward. There are many vital social services that the private sector will never want to supply because they are not inherently profitable.

Libraries are a case in point. Traditionally, governments have provided such facilities, though in recent years some have used private operators propped up by public subsidy. The argument that publicly subsidised private provision is more efficient tends to fail when one takes into account the broader effects of service splintering (contract administration, planning fragmentation, and so on).

The second rationale for social infrastructure - equity - is equally straightforward, even if it tends to get lost in technical debates about service reform. The public domain exists partly to ensure that everyone has the opportunity to use the services and facilities that are fundamental to human wellbeing.