Paving for change


In the ‘new normal’ of the pandemic, outdoor space has taken on new importance, but with the future uncertain, a fresh approach is needed to provide multifunctionality and flexibility to all spaces between buildings. Chris Hodson explains more

Apart from temporary measures for social distancing, the pandemic has triggered a fundamental rethink about our paved environment. Issues raised in the past, but put on the back- burner, are being revisited, including ‘active travel’ – increasing walking and cycling – ‘low traffic neighbourhoods’ reflecting previously adopted ‘home zones,’ and reinvented high streets responding to the growth in online shopping. A range of wider concerns also need to be addressed, such as flooding from rainwater runoff, vehicular pollution in drains and watercourses, and urban overheating.

Modular paving
Combining established techniques and new innovations, modular concrete paving systems are ideally placed to meet these challenges, whether on new or retrofitted schemes. Adopting the principles of modern methods of construction, factory-produced modular concrete paving delivers fast, low- cost installation, with limited intervention for retrofits. Importantly in these uncertain times, layouts can easily be altered and modular concrete paving taken up and re-used to meet changing demands.

These principles generally apply to all precast concrete block, flag and kerb products. They are fully engineered and manufactured under sustainable, controlled conditions – consistently providing accurate sizes, colours and textures, as well as slip/skid resistance and other performance characteristics. The distinct, modular units and designed variations in colour, texture and shape can break up areas visually, giving visual interest and a human scale not possible with monotonous, formless materials.

So, modular concrete paving delivers a unique combination of predictability, safety and accessibility for all, with scope for endless variety in shape, scale, colour and texture to enrich the urban environment. It offers urban designers the freedom to create real ‘places for people’ that are both multifunctional and adaptable to change.

Paving by design
One example of inspired design enhancing the urban realm is the regeneration of the Brownfield Estate in east London, surrounding Ernő Goldfinger’s iconic, brutalist Balfron Tower. Here, concrete block and flag paving clearly defines footways and ‘defensible’ space, as well as highlighting public spaces. Housing block entrances are announced with strong- coloured concrete flag linear paving, shared surfaces right across the adopted street itself.

A key consideration today is storm-water flood prevention – particularly with climate change – and concrete block permeable paving is uniquely placed as an essential, multifunctional sustainable drainage (SuDS) technique. In addition to paving, it also provides an inherent drainage system that requires no additional land take for water storage, treatment or conveyance. This technology eliminates pipework, gullies and manholes, and generally costs less than conventional drainage and paving.

Capturing pollution
But equally important to flooding is the long- and short-term damage caused by pollutants in surface water runoff to the biodiversity and health of our rivers and streams. The Greater London Authority ‘Road Runoff Water Quality Study’ concludes that “London’s roads are harming London’s rivers” and proposes SuDS features to manage runoff pollution from the most damaging roads. On any trafficked surface, concrete block permeable paving offers a real opportunity to address this major problem by trapping vehicle pollution.

Permeable paving can provide a completely level, well-drained, firm and slip-resistant surface accessible to all, without the need for cross-falls, channels, gulleys or other interruptions. Rainwater ‘ponding’ is eliminated, reducing the risk of ice forming on the surface and preventing splashing from standing water.

But it also allows water to reach tree and shrub roots, despite providing a hard surface above: in fact, the Code of Practice for accessibility in the external environment, BS 8300-1:2018, calls for permeable paving instead of tree grilles. And it can also help reduce ‘urban heat island’ effects, i.e. evaporation of rainwater within the paving. This is in addition to the high albedo – or heat reflectance – offered by modular concrete paving.

Retrofitted permeable paving
Bringing these issues together, an award- winning, exemplary SuDS scheme near Australia Road, London, demonstrates the multifunctional benefits of retrofitting permeable paving in place of conventional surfaces. Its design, by Robert Bray Associates, introduces the concept of concrete block permeable paving as a thin overlay to existing streets, removing rainwater straight from the surface without gullies and providing some water attenuation and treatment before discharging to adjacent, well-planted SuDS basins. This innovative concept opens up wider possibilities for all hard surfaces.

Modular concrete paving offers designers the potential to create safe, attractive and comfortable urban spaces for the post- pandemic environment, with maximum flexibility to meet future challenges and minimal interventions with retrofit, while reducing flooding, pollution and urban heating.

Chris Hodson is a consultant to Interpave