Land transport: animals, roads and highways

At first, people carried goods themselves. Then they used pack animals (horses, mules, camels, yaks, reindeer), and later wheeled carts. The steam engine (in the eighteenth century) and then the internal combustion engine revolutionised land transport, giving us railways, cars and trucks.

Roads are the most economical mode for short distances. They offer door-to-door service, and can reach places where railways cannot. But unmetalled roads become difficult in the rains, and even good roads can be cut by floods, and traffic congestion is a growing problem in cities.

The world has about 15 million km of motorable roads; North America has about 33% of them, the highest road density in the world.

Highways are long, wide roads connecting distant places, built for fast, uninterrupted traffic. Famous ones:

• the Trans-Canadian Highway, linking Vancouver in the west to St John's in the east;
• the Alaskan Highway, from Edmonton to Anchorage;
• the Pan-American Highway, linking South, Central and North America;
• the Stuart Highway, across central Australia, from Darwin to Adelaide;
• in India, the Golden Quadrilateral, linking Delhi, Mumbai, Chennai and Kolkata.

Border roads along international frontiers integrate remote people with the rest of the country, and are vital for defence.