– why don’t we do it in the road?
The road wasn’t always paved with tarmac. Just as the road wasn’t always seen as the rightful domain of vehicles. We are inured to the look of our roads, the ribbon of black tarmac which slices through every other fabric whether in town or country, ubiquitous, uniform and smooth. A lot of time and effort has been spent on the quality of the surface, to reduce tyre noise and provide a smooth, tightly knit finish which promotes user comfort and speed. Whilst tarmac usefully enables high speed and low surface noise on long distance routes these are not necessarily the criteria which are essential within towns and villages, where streets are a fundamental part of the urban realm, used not just by vehicles but shared by pedestrians and cyclists too. And where the street is not simply a route to get from place to place but is itself somewhere that people dwell.
But it wasn’t always like that. Much of Europe is still paved with granite and stone setts - 100mm3 blocks which are often set in ornate patterns, not only endlessly satisfying to look at but the tightly knit arrays also help to keep them bedded and locked together in the pavement. As well as being a beautiful, natural material with inherent variation in colour and texture, stone setts are durable, wearing for generations, unlike tarmac, which wears out in a matter of years. Their use is far more sustainable too bitumen is high in embodied energy whereas stone with its long use life is relatively low in embodied energy. But stone setts take time and skill to lay and our maintenance crews are underfunded and underskilled, more up to boshing in the tarmac than painstakingly laying non-uniform blocks.
Stone however, is noisy and in some circumstances dangerous! In the 19th century horses’ shoes could strike sparks on stone and there was the potential to ignite flammable substances nearby. In Dundee in 2011 road renovations in the city centre uncovered thousands of timber setts which had surfaced Whitehall Street and Whitehall Crescent. These ‘cassies’ were made from Pine which was veneered with an expensive hardwood such as teak or mahogany. Timber setts also deadened the noise from horses’ hooves and reduced the vibrations. They were used around military dockyards and gunpowder factories, but also around hospitals and country houses to reduce the nuisance of noise.
Solid Oak and sustainably sourced, exotic hardwood setts are still available today but are seldom used either in the street, shared or public space as a paving material. They are commonly thought to be slippery, but unlike the planked or decked surfaces which have been remarkably popular in garden make-overs they are laid end grain up. This means that the rough fibre ends naturally form an abrasive surface rather than the long smooth grain of a plank.
We used timber setts on our scheme at Sawclose in Bath. This was both a reference to the Mineral Hospital just adjoining the site, but also echos the historic site use as a saw mill, and the place where many raw materials would come into the city through the east gate. The setts make a subtle detail behind the step nosings and are a reference to those former uses
There is one drawback though, as they are laid loose on sand (and don’t require as much skill to lay them) they do float!
For comparison figures on building substances’ embodied energy see Bath University’s site http://www.greenspec.co.uk/embodied-energy.php
Report on the discovery of timber setts in Dundee:
The Craftsman Richard Sennett (2008) www.richardsennett.com
www.woodscape.co.uk supply timber setts