Dan and Bex are on a road trip. They’re thinking about how the industrial revolution changed how roads were built.
The population increased massively during the 18th century, especially in cities like London, Birmingham and Glasgow. This meant more travel, more vehicles on the road and yes, more horses!
Aside from the rather smelly problem of manure, roads had to be better to cope with the increased loads and luckily there were some very clever people at work…
Take John Metcalf – he built many roads in England in the 18th century.
An expert in drainage, he thought a good road should have a curved surface so rain water would run off. He even managed to build roads across bogs using rafts of heather and gorse.
Then there was Thomas Telford. He was a builder who came up with new ways to make roads much smoother. He built roads by digging a large trench in which a foundation of heavy rock was set.
The surface of his roads consisted of broken stone which were selected based on thickness and shape. His work on the Holyhead Road helped half the journey time of the London mail coach – from 45 to just 27 hours.
Tarmac is all thanks to another 18th century engineer – John Macadam.
He figured out that it wasn’t necessary to use lots of stones. In fact, he said “no stone larger than will enter a man’s mouth, should go into a road.”
His view was that rather than building great foundations of stones, so long as the ground was covered by a tough crust, that would protect the soil underneath from water and wear.
John Macadam used a combination of stone and soil to make this crust, which came to be known as macadam after its inventor.
In 1848 he added coal tar to the mix, creating Tar Macadam or Tarmac! This coal tar was left over from coal lamps and so he was also a pioneer in recycling!