This is both a follow-up to an earlier post on filtered permeability in de Beauvoir, and a response to the current Walford Road area consultation.
The earlier post identified three negative impacts of filtered permeability:
- Filtered permeability breaks the street network and pushes traffic away from “residential streets” on to the surrounding roads which increases congestion, air pollution, and journey times.
- By describing these areas as “residential streets” it implies that no one lives anywhere else. Often the streets that traffic is filtered towards are actually high streets with higher densities and a wider mix of uses. There are consequently more people on them, and therefore more people exposed to increased traffic and air pollution.
- The streets where traffic has been restricted are already quiet, and experience further reductions in natural surveillance, reducing personal safety (and the perception of safety).
These points were made on the basis of street network analysis, and some further investigations in to the distribution of land use and density in and around de Beauvoir.
A further consideration in the earlier study is that the resulting distribution of traffic volumes (and air pollution) is socio-economically distorted: higher density, multi-dwelling, buildings are more exposed to traffic, while lower density houses are less exposed.
The drive for filtered permeability is to encourage cycling, and this is positive for many reasons. However, cities are complex systems that work across many scales simultaneously, and are formed from different layers of infrastructure, public transport, land use, density, and people, all of which need to be considered in an integrated way.
The last fifty years of urban planning, and specifically the dominance of traffic engineering, shows how negative outcomes for the whole city arise by working with one infrastructure system in isolation from the others. Despite the positive objective, the risk of using filtered permeability to try to deliver improved cycling infrastructure is that it will create unintended negative outcomes across the wider area.
Hackney council currently has a consultation running to extend a filtered permeability scheme further north into Stoke Newington. This post uses spatial network analysis to test the impact of these new proposals.