It is this issue of city scale form and supporting infrastructure that is the focus of this article. At some point however, as we may be seeing with Beijing, the costs of developing the infrastructure to the same pattern may become prohibitively expensive and (setting aside other factors for controlling sprawl) there may be a purely economic case for limiting city size. The key factor then for planning on a city scale is how this infrastructure is designed. I would add to that the caveat ‘for any given level of infrastructure’ by investing in infrastructure such as transit the benefits of agglomeration can be achieved for longer as the disbenefits curve is flattened. At this point the optimum city size for a societal perspective has been breached. Here cities have increasing economics of agglomeration with size, realised by the firm (access to labour markets, innovations etc.), however there are also increasing diseconomies of scale borne by society (pollution, congestion etc.) hence it may individually advantage a land developer to capture the proportion of agglomeration value captured as rent even though the point of net loss (economies-diseconomies) has been exceeded. Lets look at the classic Alonso model of ‘ideal’ city size with fresh eyes. We have in recent years gained an increased appreciation of the economics of agglomeration from rapid urbanisation. Similar in most Asian megacities high rise buildings predominate – so building at high densities by itself is not the answer.įinally in China most land ownership and gains from uplift of land value are captured by local government, so this is not by itself a solution to urban dysfunction. What has gone wrong?Īlthough in most of the world informal settlement predominates in this ‘Asian’ model of urbanization planned development predominates. 3rd Ring Road, 4th ring road, all comprised of mutually inaccessible superblocks of hyper-dense development all looking the same and having similar problems. The city keeps growing and the same principles are applied but the costs of maintaining the infrastructure of the city grow exponentially. Having been schooled on schemes of fractions of a Sq KM they have to design a city at 40-50+ sqkm in area and apply the same principles. There is one task which seems to defeat urban planners around the world.