brief history of roads
Post on 18-Jan-2016
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By Steve Abrams May 16, 2013
Thousands of years before urban planning, motor vehicles, or even the
wheel, the first roads appeared on the landscape. Just as molecules
coalesced into cells and cells into more complex organisms, our first
roads were spontaneously formed by humans walking the same paths
over and over to get water and find food. As small groups of people
combined into villages, towns and cities, networks of walking paths
became more formal roads. Following the introduction of the wheel about
7,000 years ago, the larger, heavier loads that could be transported
showed the limitations of dirt paths that turned into muddy bogs when it
rained. The earliest stone paved roads have been traced to about 4,000
B.C. in the Indian subcontinent and Mesopotamia.
A Roman Road At Pompeii. The Raised Stones Were An Early Crosswalk That Kept Pedestrians Up And Out Of The StreetUIG Via Getty Images
To help support the movement of legions throughout their empire, the
Romans developed techniques to build durable roads using multiple
layers of materials atop of deep beds of crushed stone for water drainage.
Some of those roads remain in use more than 2,000 years later, and the
fundamental techniques form the basis of today’s roads.
Modern road-construction techniques can be traced to a process
developed by Scottish engineer John McAdam in the early 19th century.
McAdam topped multi-layer roadbeds with a soil and crushed stone
aggregate that was then packed down with heavy rollers to lock it all
together. Contemporary asphalt roads capable of supporting the vehicles
that emerged in the 20th century built upon McAdams’ methods by
adding tar as a binder.
The actual process of road building has changed dramatically over the
past century, going from large gangs of workers with picks and shovels to
enormous specialized machines. Rebuilding existing roads starts with
peeling up existing pavement, grinding it and dumping it straight into
trucks for reuse later as aggregate for new roads. After grading the
surface, pavers come in and lay down fresh, continuous sheets of asphalt
followed directly by the rollers.
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