Copyright © 2007 Dorling Kindersley
Many people live in one place, but work in another. At local supermarkets, people buy products from other countries. Modern transportation—the movement of people and FREIGHT by land, sea, and air—lets us travel all over the world with great speed.
Table 28. TRANSPORT FIRSTS
Road, rail, sea, and air transportation link together to make an integrated system. A package sent from London can be delivered 24 hours later to an address in Chicago. A van driver picks up the package and takes it by road to the airport. The freight plane flies overnight to the US. Its cargo is sorted, and the package travels onward by road once again.
The most fuel-efficient way to transport people and goods is by sea, but travel times are long. Rail is the next most efficient, and safe. Flying is fastest but least efficient. The best transportation for short trips is cycling or walking—both are pollution-free, keep you in shape, and help you avoid congestion.
Scientists and engineers seek solutions to transport problems. They try to reduce CONGESTION and pollution and improve ROAD SAFETY. They also work with governments to introduce scanning equipment to improve security and stop the smuggling of illegal goods across borders.
The pilot and crew use flight deck computers to fly the plane, and radar screens to show their position and weather conditions ahead. Air traffic controllers on the ground give pilots permission to take off and land, issue flight paths, and make sure that no aircraft come within 10 miles (16 km) of one another horizontally, or 1,000 ft (310 m) vertically.
Congestion occurs when too many vehicles use the same route at the same time, and traffic slows or comes to a halt. One solution is to build more roads, but some people argue that the number of vehicles grows to fill the roads available. An alternative is to encourage people to use public transportation.
The streets in many cities are laid out on a grid. At busy times, traffic may stop as traffic jams form at intersections. This is called gridlock. Gridlock may be avoided by synchronizing traffic signals from one street to the next, and by introducing one-way systems.
Public transportation is more efficient and less polluting than private cars. Underground rail can transport two million people in and out of a city each day, but two million cars can block the roads. City planners also encourage people to use trams, bicycles, buses, light rail, and riverboats to reduce congestion.
When goods are being transported, they are called freight. Almost everything you purchase—clothes, electronics, food, and books—has been brought to the store from elsewhere.
Container ships are loaded at special container ports. The containers are easily transferred from road to rail to ship because each container is a standard size, 8 ft by 8 ft by 40 ft (2.5 m by 2.5 m by 12 m). They stack together like bricks. The largest container ship can carry 4,000 containers.
Scientists are always looking for ways to improve safety on the roads so that fewer people are hurt or killed in accidents. Millions of people are injured each year in road crashes around the world, but many more injuries are not reported.
Driving too fast is a major cause of accidents. Speed increases the severity of accidents. Nine out of ten collisions with a pedestrian at 40 mph (64 km/h) are fatal, but less than one in ten are fatal at 20 mph (32 km/h). Speed bumps and traffic islands help to keep speeds down. Police patrol cars equipped with radar equipment stop speeding vehicles, encouraging drivers to obey speed limits. Electronic signs on freeways tell drivers about road conditions ahead.