Urban economists and planers have a certain obsession with compact urban development. Although not achieving a universal consensus, it is a concept that does win the majority of votes. Most of us agree that a compact urban development is better than a sprawled one. As economists we think compact development is more efficient as it allows using available resources (land & space) in a more efficient way to foster agglomeration economies and reduce congestion effects (e.g. traffic congestion). It is also thought to be a more environmentally friendly urban development, as it reduces the impact on agricultural land due to a growing urban footprint, and leads to a less-carbon intensive development. While this “urban mantra” has been preached by many, compacting already sprawled cities has proven difficult and expensive so most efforts are focused in rapidly urban centers which are mostly located in developing countries.
Because of this I am rather happy of seeing a recent study on the costs of urban sprawl from the Global Commission on the Economy and Climate (under their flagship project – The New Climate Economy). This study, led by Todd Litman from the Victoria Transport Policy Institute, brings together many of the previous studies done in the subject and highlights how certain public policies can unintentionally encourage and subsidize urban sprawl. He estimates that about two-thirds of the municipal budget is affected by lower development density and increased per capita vehicle travel. For instance, sprawl development requires more road-kilometers, street lighting to build and maintain, the same is true for other trunk infrastructure such as water supply and sewers. The analysis indicates that compared with a more compact urban development (of more than 30 residents per hectare), sprawl (typically less than 6 residents per hectare) increased per capita land consumption by 60-80 percent and motor vehicle travel by 20-60 percent. Overall, the study estimates the incremental costs of sprawl to be nearly 1 Trillion USD annually, of which 625 billion are internal costs (borne directly by sprawl location residents – increased communting time and costs of transportation) and 400 billion are of external costs (borne by other people).
The authors concludes with a set of policy recommendations depending on the level of land constraints that cities face to grow. According to him:
- Unconstrained cities which are surrounded by an abundant supply of lower-value land can expand significantly among major corridors but aim at having at least 30 residents per hectare. These cities should maintain strong downtowns surrounded by higher-density neighborhoods and while private car ownership may be common excessive use of vehicles should be discouraged by applying complete street policies (i.e. sidewalks, crosswalks, bike lanes and bus stops) and implementing transport and parking pricing schemes that discourage urban-peak travel.
- Semi-constrained cities having a limited ability to expand should combine policies of infill development and modest expansion among major corridors. These cities should also maintain strong downtowns surrounded by higher density neighborhoods. Private vehicle ownership should be discouraged and roads designed to favor non-motorized transport (cycling) and public transport. Road pricing policies should be put in place to limit vehicle use and avoid congestion.
- Constrained cities which might find it difficult to expand due to their geographic location are obliged to increase density in the form of infill development and multi-famliy housing to be able to make space for the growing populaiton. Few families own a car. These cities require strong policies to maximize livability in dense neighborhoods, the provision of public green space and the implementation of transport policies that favor space-efficient modes such as walking, cycling and public transport.
The author briefly describes the validity of his results to developing cities – stating that although costs of sprawled development should be lower they should be proportional to the lower incomes found in those countries. He also discussed briefly one of the major criticism to compact city development (that it is generally linked to higher housing prices and might be leave the poorest unable to afford housing) but in my opinion does not bring sufficiently convincing arguments. If you have some time to spare I highly recommend reading this report, or at least the Executive Summary :-).
Are you aware of similar studies done in developing cities?
The report can be found in the following link: