Why do inner city residents walk and tram to work?Posted: June 3, 2010
More than half of all trips to work by residents of the inner city are made by walking, cycling or public transport. In fact three quarters as many residents walk and cycle as use public transport for their commute.
Why? Is it because of the higher density of the inner city?
The view that density predicts more sustainable transport use is a common one. While it has some role, it is not the key force at play here. In fact there’s evidence that the population density of some parts of the inner city is not that much higher than that of the suburbs – this is because the average size of households in the inner city is relatively small compared to suburban locations.
There are also examples of higher density developments where use of public transport is quite low, for example edge cities in the US and suburban New Urbanism developments like Orenco in Portland, Oregon.
So if density isn’t the primary force driving more sustainable transport use in the inner city, what is?
Here are four plausible explanations.
The first is proximity. Inner city residents live cheek by jowl with the largest concentration of jobs in the metropolitan area – the inner city has 28% of all metropolitan Melbourne’s jobs and the CBD, despite its diminutive geographical size, has 14.5%. There is no other location in Melbourne that comes within cooee of the job density of the CBD.
The second explanation is high socioeconomic status. A disproportionate number of inner city residents work in high-paying jobs that are only located within the CBD or nearby e.g. corporate and Government headquarters and the high-level legal and business consulting firms that provide services to them. These workers are Robert Reich’s “symbolic analysts”.
The third explanation is the quality of public transport. Inner city residents have access to comprehensive and high quality tram and rail systems that converge on the inner city and CBD. This gives them many opportunities to “connect” between routes and modes. The high quality of public transport is not due to the inner city’s density but rather to its proximity to the CBD – it would still have excellent tram and train services even if the dwelling density were reduced to quarter acre blocks!
The final explanation is traffic congestion. Residents of the inner city confront some of the worst congestion in the metropolitan area because of the concentration of (non-residential) destinations – the most obvious concentrations are workplaces and schools. Walking, cycling and public transport can be faster than driving when congestion is present, especially where the workplace is close by.
I’ve left out car ownership because I think the lower rate shown by inner city residents is more plausibly a consequence of the factors I’ve mentioned above, rather than a cause.
Thus while there is a correlation between dwelling density and use of more sustainable transport modes in the inner city, there are a number of other inter-related factors that seem to have a stronger causal role than density.
The importance of this analysis is that it should not be assumed that density alone will automatically lead to more sustainable transport use. If all new housing on the periphery, for example, were built at comparable density to the inner city (and nothing else were changed), it is unlikely there would be a significant increase in the share of work trips made by walking or public transport.
This is because outer suburban residents are not close to any major job concentrations and the vast bulk of them work in the suburbs where jobs are spread at low densities – only a small proportion work in the CBD. Public transport is usually poor and even if it were many times better, the relative absence of congestion in the suburbs means it will almost always be faster to travel to work by car.