Built to last
Approximately 75% of the roads in southern England and the Midlands today are built on top of Roman roads. Most of the originals were made of smashed flint and gravel, with a cambered surface of paving stones to prevent flooding.
Not all Roman roads conformed to the stereotype of a dead straight thoroughfare built for large armies to march on. Many were unpaved tracks, meandering along routes established earlier by the native population.
The scale of major Roman road building was positively industrial.
More than three million tonnes of stone were brought in from quarries all over the region to build Watling Street, which ran from Richborough in Kent - near the point where the Romans first landed - to London.
The most important Roman roads, such as the Fosse Way between Exeter and Lincoln, had no respect for the existing landscape. They frequently cut across traditional tribal boundaries, creating ethnic tensions. There is evidence that the Romans exploited these tensions in the course of subjugating local tribes. When Boudicca's army rose up in revolt, they used Roman roads to march against the occupier.
The unerring straightness of some Roman roads was achieved by using a simple device called a groma, two plumb-lines descending from a horizontal wooden frame. But the groma was only effective in calm conditions - a strong breeze would blow the plumb-lines out of whack.
Roman roads created a boom in transport, trade and communications. Travellers' inns were built at specific distances along the road, and clearly marked on the Romans' impressively accurate road maps. An efficient postal system knitted the empire together.
The Romans came up with the first automated means of measuring distances. The odometer was a chariot with large wheels that turned exactly 400 times in one mile. After each mile a pebble called a calculus would drop into a box, enabling the total distance of the journey to be measured. Milestones were erected to mark each mile, the equivalent of about 0.8 of the mile we use today.