November 08, 2004

Horse 224 - Tarmac

John MacAdam was a wacky Scotsman who single handedly changed the way roads were built... well not exactly. Born in 1756 he moved to America and worked in his uncle's accounting firm. News would filter though every other month from home and among one of the mails was a story about a fellow called John Metcalfe.

Mercalfe was otherwise known as "Blind Jack", he had become blind at the age of six and by his mid 20's was literally appalled with the state of roads in Britain. On one famous journey from London to Birmingham he refused a lift from a stagecoach and told them it would be quicker if he walked - he was right, he was quicker by six days.

Metcalfe wanted better roads in his native Yorkshire, so being an enterprising chap, built some. He managed to chart and built 180 miles of good turnpike road in Yorkshire by building up a raised surface which drained into side ditches. To this day, no-one knows how he managed to chart his way across the Penines let alone where to put his road.

Word spread to MacAdam and on his return to Scotland in 1783 MacAdam purchased an estate at Sauchrie, Ayrshire, and started experimenting with a new method of road construction. When he was appointed surveyor to the Bristol Turnpike Trust in 1816 he remade the roads under his control with crushed stone bound with gravel on a firm base of large stones. A camber, making the road slightly convex, ensured the rainwater rapidly drained off the road and did not penetrate the foundations. This way of building roads later became known as the Macadamized system. As a result of his success, MacAdam was made surveyor-general of metropolitan roads in England. Eventually the roads were sealed with a tar-gravel layer, hence the name Tarmac.

So why post such a thing today? No reason other than I heard a Scot and a Yorkshireman arguing about putting up a speed-hump near where I work.

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