Has PTAL reached the end of the road?\

Since its introduction as a planning tool, PTAL, or the Public Transport Accessibility Level score has become a factor with considerable weight when considering the density of new development in London.

Despite the benefits of recognising transport provision within the planning process, it is becoming increasingly apparent that PTAL is a crude tool that lacks the nuance required when dealing with the uniquely dynamic and changing growth forecasts for London and the complex urbanism that results.

Around half of Outer London has a PTAL of 0-2. If this could be increased to 4-6 it would allow housing density to double. There are also examples of circumstances where the quality of urbanism, particularly on large residential regeneration sites, would be improved by a relaxation of the rules to allow appropriate density to be considered in terms outside the mechanical application of what many consider a flawed metric.

How can this be resolved in a cost effective manner? A simple answer is to include TfL’s Cycle Hire Scheme within PTAL calculations.

PTAL was originally based on walking distance from a site to the nearest 'service access points' (SAPs) - a bus stop, station or the like. Each area is graded between zero and six, where a low score indicates poor access to public transport and six is considered to have excellent connections.

London Plan policies now link density levels to the PTAL rating of an area, which has had the effect of promoting dense urban living close to SAPs and discouraging car usage. The threshold for developments is relatively steep, such that in urban areas a low PTAL of 0-1 results in densities of up to 250 habitable rooms per hectare (hr/ha), a PTAL of 4-6 allows 700 hr/ha, and in Central London, where PTALs are generally higher, this increases from 300 hr/ha to 1,100 hr/ha.

On large sites, it is common for PTAL to vary across a site. This can result in random density contours which do not make the most effective use of land and, if applied mechanically, do not respect the urban character of an area.

Another commonly cited glitch in the PTAL calculation is that it takes frequency of service, but not destinations into account, resulting in a situation where a bus every 12 minutes going to the City Centre scores less than a bus every 10 minutes that terminates at the end of the street.

While it doesn’t provide a solution for all users, cycle hire has huge latent potential in London: in 2014 there was a 25% increase in London cycle hire journeys and this trend is set to continue. With a cycle, each rider has the freedom to travel where they want, provided they can find an empty Docking Station at the end of their journey.

There are constant calls to expand the Cycle Hire Scheme into Islington, Hackney and South London. Such expansion is currently thwarted because a portion of the expense of providing additional bikes and docking stations falls on cash-strapped Local Authorities. With recognition or cycle hire through PTAL, and the consequent increase in development density, these areas could easily fund the cycling infrastructure. Outer London use could be further enhanced with mini-hubs serving local communities around rail stations.

“How can this be resolved in a cost effective manner? A simple answer is to include TfL’s Cycle Hire Scheme within PTAL calculations.”

Deptford Wharves previous scheme

Deptford Wharves new scheme

In 2011 Hawkins\Brown obtained planning permission for ‘The Wharves’ in Deptford, a mixed use scheme delivering 905 homes, retail and workspace. The site was sold to Lend Lease in 2013 and we was re-appointed to take a fresh look at our earlier design. As is common on larger regeneration projects, the PTAL rating ranges from 1a to 3 across the site, which provides an artificial constraint along one side of the development. Our revised design, which obtained planning approval at the end of 2015, challenged some of the preconceived density limits and responded to local context which varies considerably around the site, from busy main roads, to quieter streets and post war housing estates. By successfully arguing for a relaxation of the PTAL requirements, density has been optimised from 200 dwellings per hectare to around 240, giving a new total of 1130 homes.

The above example has increased density by around 20% but on other sites, this could be significantly more if PTAL itself is reviewed.

An edited version of this article has been published in the March issue of NLQ

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