Benjamin Derbyshire, Managing Partner at HTA Design LLP
The question is where to locate different urban forms in relation to our street network so as to enhance street life, not whether high rise is appropriate in London.
The long and rich history of European urbanism has been – until the 1960’s, at least – predicated on the ordering principles dictated by the urban street. Our street network and our tradition of street life is the European city’s greatest asset. In London, as an example, our success in creating mixed communities and a lively mix of uses is the envy of the world. Here, streets are a means of comfortably juxtaposing diverse backgrounds, cultures, activities and, with appropriately sensitive urban design, a diversity in the scale of built form too.
Today, learning from the disasters of the post war years, citizens increasingly demand that their city should be developed as an extension of the network of these streets. They expect access to all areas on ground that is in public ownership and that is policed by consent, ground that is by definition shared space and under collective control. Streets provide a recognisable physical language that reinforces public safety and control through the passive supervision of witnessed comings and goings. We enjoy a sophisticated legislative framework which supports these principles.
One of the reasons London has become such a desirable destination for people and their money from all around the world is that this powerful democratic principle instils order and a sense of safety and security. So London is once again attracting people in large numbers to come and stay, and the haemorrhaging of London’s indigenous population has been staunched so young Londoners no longer flee to safer places to bring up their children. The resulting rise in population has reopened the discussion of density and in what built form to create new accommodation.
The debate has crystallized lately around the question of the suitability of high-rise housing and the current plans for up to 200 towers to be built in London, which many suggest would ruin the city’s historic skyline. However, we believe this debate as to whether or not high-rise is appropriate in London detracts from another issue of equal if not greater importance. This is the question of where to locate different urban forms in relation to our street network in the interests of promoting street life.
The phrase ‘street life’ sums up in two words the essential focus for successful placemaking. The phrase captures the human dimension; creating an environment that works for people; the fulfilment of the various public aspects of life as the paramount consideration for designers and developers of successful places – places that enable and support enjoyable human existence. Streets are the theatre in which this urban existence is played out. Streets are also the connective tissue that holds the city together, supporting not just movement but carrying essential infrastructure. Thus ‘street life’ encapsulates the key human and spatial ingredients of placemaking.
Moreover, as our population increases and cities become inevitably denser, it becomes increasingly important to accommodate more intense human activity comfortably and safely. Population density and the intensity of human activity varies from time to time and from place to place. Good design recognises these dimensions and addresses sparse and intense, active and passive human activity. The design requirements at the opposite ends of this spectrum of human intensity are widely different. There are extreme cases with different remedies for intervention – one where the population density is too low (which HTA are considering in our Supurbia project), and the other where too many people jostle for the available space and where design for Superdensity is the key.
In outlying residential areas (to digress for a moment from the consideration of Superdensity), where pavements are relatively devoid of movement, the challenge is a design which supports a residential community’s natural propensity for mutual support and reinforcement. Neighbourhoods that work well are those where it is easy for people to look out for one another, oversee children’s play, keep an eye on the environment and see off miscreants. Once again, street life is the operative phrase, brought about by the orthodox familiarity and the ordering principles of traditional street design: Street doors, bay windows, balconies and most importantly, a relationship between the disposition of internal functions with the public and semi public realm that permits privacy at the same time as the passive supervision of what goes on in the street outside.
At our Hanham Hall scheme, for example, we have successfully re-introduced the veranda or stoop as a mechanism for increasing human interaction at low densities. This is relevant to the consideration of high density because the successful intensification of large areas of low density suburbia can radically reduce the pressure on high density locations.
Where movement and footfall converges on transport connections with high density of mixed uses, the challenge is to create space that permits people to linger and interact at the same time as others are free to move easily to and fro by various means (it’s worth emphasising the growing influence of the bicycle amongst other modes). Here the ground plane is in intense demand and success lies in making a generous allocation of comfortable sheltered space, safe from traffic and removed from noise and fumes.
Close to transport hubs and where there is a high intensity of commercial, retail and leisure use, pavements are so overcrowded that pedestrians jostle in dangerously uncomfortable proximity to busy traffic. Here the issue is to create more high quality outdoor space to accommodate pedestrian movement and provide a suitable environment for people to sit, rest or enjoy café life free of noise and pollution. Courtyards, arcades, canopies, logias, belvederes and terraces are useful devices to achieve this and these should be designed bearing in mind orientation, aspect and shelter to create comfortable microclimate.
In these places, not only is the additional cost of high rise offset by the extra value derived from proximity to transportation, but the higher plot ratios and relatively small footprints create the opportunity to make more ground level space for people to move and congregate. It is usually a mistake to take up the ground plane with built form, often podia with towers over. This forces people to the kerb edge and into conflict with traffic and each other through overcrowding.
The design of space between the base of superdense buildings needs to be such as to allow sunlight to penetrate and views glimpsed from surrounding approaches. The form of tower structures therefore needs to be slender with adequate space between. Windbreaks should be incorporated at about second floor level to deflect downdrafts and provide shelter from rain for cafe goers and shoppers. Towers designed like this can further enliven the space at their base, disgorging occupants at ground level so as to contribute custom to shops, cafes and services. Clusters of such towers should be composed with the tallest at the centre of the group, falling away to the edges.
The design of the public realm has the job of successfully spanning these extremes of usage at the same time as holding a neighbourhood together, creating a recognisable language of materials, details, hard and soft landscape that is familiar, legible and identifiable with the location. The design of the public realm contributes powerfully to a coherent sense of place capable of communicating its identity as an attractive destination to live, work or play.
Robust simplicity is the way to achieve the integrating function of well designed public realm. A high quality pallet of durable materials with simple delineation of space allocated to different functions works best because over-elaborate geometrical design creates confusion and is hard to maintain. But perhaps the most important ingredient is the successful integration of substantial elements of planting. It is especially effective in the early days of creating a desirable destination for newcomers to be struck by the sense of established well-being that is imparted by well established greenery.
Thus in reality the question is where to locate different urban forms in relation to our street network, and the task one of creating liveable, safe, sociable and self sustaining neighbourhoods. When the London Plan was first published it was evident that it lacked a spatial dimension based on an urban design analysis which would provide any kind of clear indication as to where to add density in the city. The PTAL map does not engage meaningfully in a wide enough range of the issues that bear on good Placemaking. Indeed, it could be revised substantially to allow much higher density in some areas, particularly if the question of street life was properly addressed.
Thus, a Placemaking analysis, with a particular focus on improving the environment for pedestrians at ground level, permitting the quiet enjoyment of pavement and public realm in a suitable microclimate, actually generates a strong argument for the vertical extrusion of built form so as to liberate and enliven the opportunity for street life. There are places where the circumstances are right for superdense schemes and we would urge that this opportunity is not overlooked, in an erroneous analysis suggesting that towers are out of place anywhere in London.