Transportation

VI

History

The history of transportation is largely one of technological innovation. Advances in technology have allowed people to travel farther, explore more territory, and expand their influence over larger and larger areas. Even in ancient times, new tools such as foot coverings, skis, and snowshoes lengthened the distances that could be traveled. As new inventions and discoveries were applied to transportation problems, travel time decreased while the ability to move more and larger loads increased. Innovation continues today, and transportation researchers are working to find new ways to reduce costs and increase transportation efficiency.

A

Animals and the Wheel

The domestication of animals was the first great leap in transportation ability. However, the use of animals to pull vehicles or to carry riders had to await several important inventions. At first, oxen and horses were harnessed to vehicles by neck straps, which tended to choke them when they pulled heavy loads. Finally, around ad 500, someone devised a padded collar that rested on the animal’s shoulders. The use of such a collar increased the amount of weight that the animal could comfortably pull. Horse stirrups were in use in India and Asia by around 200 bc, allowing riders to maneuver their horses more effectively. Saddles were introduced in Europe around ad 200. Horseshoes, used to protect the hooves of a horse, were in widespread use by about 700.

The first major innovation in wheeled transport was the spoked wheel. By using a spoked wheel instead of one made of solid wood, faster and more maneuverable vehicles could be designed. Protruding copper nails placed in the wheel to provide greater traction were introduced around 2000 bc. Iron rims fastened to the edges of wheels were introduced in 700 bc. These rims increased the strength and durability of the wheels. The harnessing of multiple animals to a single vehicle began around 100 bc. These innovations all contributed to increasing the weight that a wheeled vehicle could carry.

The wheel, when applied in wagons and carts, was the first transportation innovation to create the need for roads that could survive repeated use. Early roads built—usually by slaves—in Rome, India, Persia, and China were made of brick or stone. These ancient roads fell into disrepair during the Middle Ages. However, the resurgence of travel and trade during the Industrial Revolution in the 18th century in Europe created the need for additional roads and new methods of construction. The most important innovation was the use of well-compacted, small stones in a soil foundation. Called macadam, after its inventor John Loudon McAdam, this new type of road construction simplified road building and enabled many kilometers of new roads to be built.

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B

Water Transportation

Oars and sails represent the two early advances in water travel, increasing both ship speed and reliability. With oars, ships could be rowed against the current and could still move even if facing unfavorable winds. With sails, ships could harness the tremendous energy of the wind to travel long distances. One of the most important early discoveries was the lateen sail, a triangular sail that could convert side winds into forward force. The lateen sail allowed ships to sail against the wind, or tack. It was the major sail technology used by seafaring people in ancient times. The stern rudder, which allowed greater control of ships, replaced the side steering oar in the 8th century ad in China and in the 12th century in Scandinavia.

In navigation, great advances were made that allowed ships to venture to sea and safely return. Early oceangoing ships generally stayed close to shore, but by the 100s bc, primitive astrolabes had been developed to help determine latitude. Thus, seafarers could determine their position at sea. The astrolabe was succeeded by the octant, and in 1757 the sextant was invented. The sextant remained the most accurate device to measure latitude until the 20th century. To determine direction when visibility was poor, the Chinese used a lodestone spoon spinning on a bronze plate as an early compass. By the 12th century the magnetic compass was being used as a navigation aid. With the increasing sea exploration of the world that began in the early 1400s, the art of mapmaking blossomed. With accurate maps, explorers could find their way when their location was checked against known landmarks. See also Map: History of Maps.

The most important technological development for inland water transportation was the invention of the canal lock. The lock connects stretches of canal built at different elevations. Although a simple canal lock was used by the Chinese as early as 984, the most extensive use of locks was found in Holland, where usable locks were in operation by 1373. Italian engineers invented the pound lock in the late 1400s. As the forerunner of today’s two-gated lock, the pound lock allowed ships to enter one end of a canal and, after water was added or removed, to exit at the other end at a different water level.

C

Steam and Internal-Combustion Engines

The development of the steam engine in the 18th century revolutionized transportation on both land and sea. The first steamboats were very simple designs with large paddle wheels that provided the ability to move against the current. Not until iron-hulled ships and the more efficient screw propeller were developed in the late 1800s did steam-powered ships begin to dominate world trade routes. With the reliability and capacity of the steamship, global markets tied together by transportation links became a reality. Ship designs became customized to carry specific types of cargo. For example, tankers were designed for carrying liquids, bulk freighters for general cargo, and, more recently, ships were designed to handle containers.

The steam engine, when applied to railroads, increased dramatically the freight- and passenger-carrying capacity of a nation’s transportation system. Improvements to the steam power plant greatly increased steam pressures. Perhaps the greatest innovation occurred in the railroad track itself. Early railway tracks were built of long wooden rails with iron straps fastened to the tops. This design soon became obsolete because of its inability to carry heavy vehicles. In the mid-1830s this design was replaced with the T-shaped iron rail still used today. In addition, the adoption of a standard gauge, or track width, provided continuity in rail service from one location to another.

One of the major technological advances in rail transportation was the development of the diesel locomotive. As compared to the steam engine, the diesel locomotive engine required less maintenance, used fuel more efficiently, was quicker to start, and reduced the amount of soot and pollution in cities. First used in 1925, the diesel locomotive had replaced steam engines in the United States by the late 1950s.

As important as the railroads were to transportation history, the internal-combustion engine had an even greater effect. The engine powered the automobile, introduced in the early years of the 20th century, and forever changed the way people move from place to place. Several innovations in the motor vehicle itself were necessary before it became the common method of transportation used today, as early automobiles were less than convenient. Gradual improvements such as the automatic starter, safety plate glass, pneumatic tires, hydraulic brakes, improved suspension, and automatic transmission each made the motor car more appealing to the consumer. New production methods revolutionized manufacturing worldwide. American industrialist Henry Ford’s large-scale adoption of the assembly-line production process in 1913 greatly increased production and made the automobile a form of personal transportation that millions of ordinary people could afford.

The internal-combustion engine also had a significant effect on air travel. Early steam engines proved too heavy for practical air travel. The first airplane flown by the Wright brothers in 1903 was powered by a gasoline engine. Subsequent development of the jet engine allowed even greater speeds and distances, making possible world travel within a 24-hour time period.

D

Recent Trends

Recent innovations in technology have been driven by a desire to find safer, faster, and more reliable means of getting from place to place. For passenger transportation, speed and convenience are primary goals. For freight transportation, speed, reliability, and efficiency, or carrying more cargo for less money and arriving on time, have been the motivating factors.

Several technologies that are shaping society in a variety of ways will likely characterize the future of transportation. Intelligent transportation systems apply the latest advances in computers and electronics to better control vehicle operations. Computerized road maps used with the Global Positioning System (GPS) help drivers to navigate. Companies that use fleets of vehicles, such as delivery companies, can use satellite technology to monitor the location of their vehicles at all times and improve efficiency.

Research is also being conducted into improving the materials used for transportation vehicles and infrastructure. Composite material, which is a hybrid consisting of many different component materials, can provide lightweight, extremely strong, and highly durable material for vehicle construction. With the lighter weight, vehicles can become more fuel efficient. New materials for pavements and bridges will also provide for stronger and longer-lasting infrastructure.

Fuels and propulsion technology are other important areas of research and innovation. Most modern transportation systems rely on petroleum for energy, but this source of energy is finite and creates serious environmental effects when used in the internal-combustion engine. Research into alternative fuel sources, such as electrical storage, natural gas, methanol, ethanol, fuel cells, and solar energy, will continue in order to ensure a reliable supply of energy for the transportation systems of the world. Several new forms of propulsion are also being investigated. For example, magnetically levitated trains, in which magnetic forces lift, propel, and guide a vehicle over a guideway, are being developed in Germany and Japan. Such trains have achieved speeds up to 500 km/h (300 mph).

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