Transportation is the act of moving people or goods from one place to another. Transportation takes people where they need or want to go, and it brings them the goods they need or desire. Without transportation, there could be no trade. Without trade, there could be no towns and cities. Towns and cities are traditionally the centers of civilization. Therefore, transportation helps make civilization possible.
Throughout most of history, transportation was extremely slow and difficult. In prehistoric times, people traveled mainly on foot. They transported goods on their backs or heads or by dragging them along the ground. About 5000 B.C., people began to use animals to haul loads. By 3000 B.C., wagons and sailing vessels had been invented. The use of animals, wagons, and sailing vessels enabled people to transport loads farther and more easily than before. But the speed of transportation improved only slightly over the centuries.
Inventors produced the first engine-powered vehicles during the late 1700’s and the early 1800’s. This development marked the beginning of a revolution in transportation that has continued to the present. Today, jet airliners carry travelers nearly as fast as, or faster than, the speed of sound. Freight trains, trucks, and giant cargo ships haul goods to buyers in almost all parts of the world. Automobiles, buses, and passenger trains provide convenient transportation for millions of people.
In some countries, governments own and operate transportation services, such as airlines and railroads. In other countries, almost all transportation is privately owned, and national and local governments only build and maintain public roads and related facilities.
Although engine-powered transportation has benefited people in many ways, it has also created several difficult challenges. For example, the engines use great quantities of fuel and so strain the world’s energy supplies. Automobiles jam many streets and highways, making travel slow. In addition, their exhaust fumes pollute the air. Manufacturers, governments, and independent organizations are seeking ways to solve such problems.
This article discusses the kinds of transportation, the history of their development, and modern systems of engine-powered transportation. The article also discusses the transportation industry and current developments in transportation. Vehicles are also used for recreation, warfare, and space exploration. These uses are described in such articles as Air force; Balloon; Boating; Navy; and Space exploration.
Kinds of transportation
There are three main kinds of transportation: (1) land, (2) water, and (3) air. Land transportation depends mainly on wheeled vehicles, especially automobiles, buses, trains, and trucks. Ships and boats are the most important water vehicles. Air transportation depends almost entirely on airplanes. 
Each kind of transportation can further be classified according to whether the vehicles are engine powered or engineless. Most engine-powered vehicles have gasoline, diesel, or jet engines. The majority of engineless vehicles are powered by the muscles of human beings or animals or by natural forces, such as the wind or flowing water.
Engine-powered transportation has many advantages over engineless transportation. It is usually faster and more dependable, and it can carry greater loads. However, such transportation is costly. Engine-powered vehicles are expensive to build and to maintain. In most cases, each type of vehicle also requires certain infrastructure (supporting facilities). Automobiles need roads. Trains must have tracks. Airplanes require airports. Ships need docks and ports. All these facilities are expensive to build and maintain. Every form of engine-powered transportation also requires a source of energy. The combined cost of the vehicles, supporting facilities, and energy makes engine-powered transportation extremely expensive. Loading the player...
Segway
Engine-powered vehicles are the chief means of transportation in industrially developed countries. Engine-powered vehicles also provide transportation in the urban areas of most developing countries, including many African, Asian, and Latin American nations. However, many people who live in rural areas of these countries still rely on the kinds of engineless transportation their ancestors used hundreds or thousands of years ago.
Land transportation
is the most common kind of transportation by far. In many cases, it is the only suitable or available transportation. 
Engine-powered land transportation.
Automobiles, buses, motorcycles, snowmobiles, trains, and trucks are the chief engine-powered land vehicles. All these vehicles except snowmobiles ride on wheels. Pipelines are another important form of engine-powered land transportation.
Automobiles, buses, and trucks are the main engine-powered road vehicles. In areas well served by roads, they can provide a variety of transportation services. Automobiles enable people to travel whenever and by whatever route they choose. Buses carry passengers along fixed routes between and within cities. Trucks can provide door-to-door freight service.
Motorcycles are used for transportation on the same road surfaces as automobiles, buses, and trucks. People also ride motorcycles off-road—that is, on country trails and other rough, unpaved surfaces.
Unlike road vehicles, trains ride on tracks. As a result, trains usually cannot provide door-to-door freight service, as can trucks, or convenient connecting services, as can buses. But trains can haul far heavier loads than trucks can. They can also carry many more passengers than buses can. 
A variety of off-highway trucks carry loads at construction sites, lumber camps, mines, oil fields, and quarries. At certain road-construction sites, for example, huge earth movers cut into hills, carry the rocks and dirt along, and drop them into valleys to make a roadbed with gentle grades (slopes).
Snowmobiles skim across ice or snow. The vehicles have two skis at the front and a moving track at the rear. An engine powers the track, which propels the vehicle.
Pipelines provide transportation, but the pipes themselves do not move. Most pipelines are built across land, but some span rivers or other bodies of water. Pipelines transport chiefly liquids and gases, especially petroleum and natural gas. Engine-powered pumps force the liquid or gas through the pipes.
Engineless land transportation.
Walking is the most basic means of transportation. Carrying a load on one’s back or head or using animals to carry loads is also basic. Animals used for this purpose are called pack animals or beasts of burden. They include camels, donkeys, elephants, horses, llamas, mules, and oxen. People use pack animals mainly in regions that lack modern roads. Such regions include deserts, mountainous areas, and jungles. 
People use their muscle power to move such wheeled vehicles as carts, bicycles, and pedicabs. A cart is a small box-shaped vehicle with two or four wheels and an open top. A person may either push or pull a cart. Bicycles are two-wheeled vehicles that the rider powers by means of two pedals. Many people use bicycles to travel to and from work or merely for recreation. A pedicab resembles a bicycle but has two rear wheels instead of one. It also has a passenger carriage at the front or rear. Pedicabs are used as taxicabs in some Asian countries.
Animal-drawn carts and wagons are a major means of transportation in rural areas of developing countries. Carts are usually pulled by donkeys, horses, or oxen. Wagons are large four-wheeled carts that can carry heavy loads. They are pulled by exceptionally strong animals, such as oxen or draft horses.
Water transportation
depends mainly on boats, ships, and rafts. Any small watercraft is classed as a boat. People use boats chiefly on rivers, canals, and lakes. A ship is a larger vessel sturdy enough for ocean travel. A raft is a floating platform constructed of such materials as logs or barrels.
Engine-powered water transportation.
Engines power nearly all ships and many boats. Most ships specialize in hauling cargo. Cargo ships travel mainly on ocean waters and on bodies of water linked to the ocean, such as the Mediterranean and the Baltic seas. Some cargo ships operate on large inland waterways, such as the Great Lakes. 
Some engine-powered boats, especially tugboats, are used in hauling freight. Tugboats have powerful engines that enable them to tow heavily loaded barges. Barges are actually large rafts. Most barges must be pushed or towed. Others have engines and so move under their own power. Barges are used mainly to haul freight along inland waterways.
In general, ships and boats are the slowest engine-powered vehicles. However, engineers have developed two fast water vehicles—hydrofoils and hovercraft.
Hydrofoils skim across the water on skids or runners. Hovercraft, or air cushion vehicles, ride above the water on a cushion of air. One or more powerful fans inside the vehicle create the air cushion. Because hydrofoils and hovercraft ride out of the water, they can travel faster than other watercraft of equal power. Most hydrofoils and hovercraft are too small for ocean travel. They are used mainly to carry passengers locally. Some larger hydrofoils and hovercraft are used to haul cargo along inland and coastal waters. 
Except for cruise ships, few ships specialize in transporting passengers. However, various types of motorboats carry passengers locally.
Engineless water transportation.
Engineless water vehicles include dugouts, canoes, rowboats, sailboats, and rafts. People use paddles or oars to propel dugouts, canoes, and rowboats. Sailboats are powered by the wind. Rafts may be propelled by paddles, poles, sails, or water currents. 
Broad-bottomed sailboats and rowboats are widely used to haul freight in the Far East. The sailboats are called junks, and the rowboats are known as sampans. Large junks have as many as five sails and can carry more than 100 tons (90 metric tons). Most sampans haul light cargo. However, many larger sampans have a sail, which enables them to haul heavier loads. In the tropical rain forests of Africa, Asia, and South America, many villagers use dugouts or rafts for transportation along the rivers. Many people of the Pacific Islands use dugouts for travel between islands. Some of the dugouts are equipped with outriggers and sails.
Air transportation
depends almost entirely on engine-powered craft, especially airplanes. Engineless vehicles, such as gliders and hot-air balloons, are used mainly for recreation or advertising.
Airplanes provide the world’s fastest practical means of transporting both passengers and freight. Only rocket-powered spacecraft travel faster. Big airliners routinely fly 500 to 600 miles per hour (mph), or 800 to 970 kilometers per hour (kph). Most private planes and some older airliners are powered by gasoline engines and driven by propellers. Nearly all newer airliners and some private planes have jet engines. Supersonic jets fly faster than the speed of sound. The speed of sound is about 760 mph (1,225 kph) at sea level, but it declines as altitude increases. Supersonic jets travel at about 1,500 mph (2,400 kph). 
Most airliners chiefly carry passengers. Even the biggest planes can carry only a fraction of the weight that a ship or train can haul. Air freight rates are high as a result. The high cost limits the shipment of goods by air to expensive, lightweight, or perishable cargo.
Helicopters, like airplanes, are powered by engines. But helicopters are smaller than most airplanes and cannot fly as fast or as far. Nor can they carry as many passengers as airplanes. Helicopters therefore play a secondary role in air transportation. However, they are much more maneuverable and have certain special uses. For example, helicopters are used in rescue work and in fighting forest fires.
History
Prehistoric times.
Transportation developed slowly until about 3000 B.C. Throughout most of the prehistoric period, people lived by hunting, fishing, and gathering wild plants. They had no beasts of burden, wheeled vehicles, or roads. People traveled on foot and carried their infants and belongings strapped to their backs. Some carried belongs on their heads. Loads too heavy for one person to carry were strapped to a pole and carried by two people. 
In time, people learned that they could drag loads along the ground on sledges (heavy sleds). They made sledges from logs, poles, or anything else that could hold a load and that one person or more could drag. During late prehistoric times, people began to build sledges with runners. These vehicles slid along the ground more easily than runnerless sledges. In far northern regions, people built lightweight sledges with runners for use on snow and ice. These vehicles became the first sleds.
By about 8000 B.C., people in several areas around the world had developed agriculture and begun to establish permanent settlements. Trade between settlements then started to develop, thus creating a need for better means of transportation. The donkey and the ox, which had been domesticated (tamed) to serve as work animals, helped meet this need. Between about 5000 and 3500 B.C., people began to use donkeys and oxen as pack animals. Next, they invented harnesses so that the animals could be used to pull plows and, later, sledges. The use of donkeys and oxen as beasts of burden enabled people to transport heavier loads than they could before.
People also began to develop water transportation during prehistoric times. They built rafts of such materials as logs or reeds. Later, people learned how to make dugouts and canoes. People paddled these early craft with their hands or propelled them with paddles or poles.
These early vessels were fragile, and they were used mainly on rivers and lakes. But archaeological evidence shows that some people used such craft on the open sea. For example, between about 10000 B.C. and 8000 B.C., traders traveled between the Greek mainland and the island of Milos in the Mediterranean Sea.
The wheel was invented about 3500 B.C. The invention probably took place in Mesopotamia, a region of the Middle East. The Egyptians invented sailboats about 3200 B.C. During the following centuries, wheeled vehicles and sailing vessels revolutionized transportation.
The first great civilizations
arose in Mesopotamia and Egypt between 3500 and 3000 B.C. From these two centers, civilization gradually spread westward along the shores of the Mediterranean Sea. Sailing vessels played a vital role in the spread of civilization. Sea voyagers transmitted ideas and inventions as they sailed the Mediterranean. Trade goods carried by vessels included weapons, seeds, and food. 
The early Mediterranean civilizations flourished from about 3000 B.C. to A.D. 500. During this period, improvements in sailing vessels and wheeled vehicles accounted for the chief advances in transportation.
Early development of sailing vessels.
By 3000 B.C., the Egyptians had learned to build sailing vessels sturdy enough to put out to sea. Some of these ships ventured onto the Mediterranean and Red seas on short trading journeys. Between 2000 and 1000 B.C., the Minoans and other Mediterranean peoples developed larger and sturdier vessels. By 1000 B.C., the Phoenicians, who lived along the eastern shores of the Mediterranean Sea, had built a large fleet of merchant ships. The Phoenicians sailed the length of the Mediterranean, from their home waters to Spain. They traded such goods as wine, oil, and laurel and cedar wood, as well as textiles, pottery, and other manufactured goods.
Sea travel remained slow and difficult throughout ancient times. Sailors lacked navigation instruments. As a result, they usually stayed within sight of land. The ships were hard to steer because they had no rudder. Sailors steered them by means of one or two oars at the stern.
In addition, the ships could not depend entirely on the wind for power. The earliest ships had a single sail, which worked well only when the wind blew from behind. For times when there was no wind, many ships had teams of rowers.
Early development of wheeled vehicles.
The first known wheeled vehicles were built about 3500 B.C. Many scientists believe that wheeled vehicles were first made in Mesopotamia. The technique spread quickly throughout much of Europe and Central Asia. It reached China and India about the mid-2000’s B.C.
The first wheeled vehicles were two- and four-wheeled carts that were pulled by oxen. After about 3000 B.C., donkeys were also used to pull carts. Some early wheels were made from a single plank of wood. But usually each wheel on a cart was a wooden disk made from three rectangular boards.
To construct a wheel, a wheel maker fastened the boards together on edge with wooden braces to make a square. The square was then rounded at the corners to form the disk. These wheels were heavy. The early carts bumped along slowly and probably had to stop frequently for repairs.
The wheelbarrow was invented much later. The Chinese invented the wheelbarrow by about A.D. 100. But Europeans did not develop it until the Middle Ages, which began about the A.D. 400’s.
In ancient times, carts were buried with important people as a sign of honor. After 3000 B.C., carts drawn by donkeys carried Mesopotamian troops into battle. Carts were also used to carry passengers and to haul grain, sand, and other goods that were difficult to load onto sledges or pack animals.
Wheels continued to be made of three solid pieces of wood until about 2000 B.C. Between 2000 and 1500 B.C., the first spoked wheels appeared. These wheels consisted of a rim, a hub, and spokes. The wheelmaker constructed these parts separately. Spoked wheels provided smoother riding than solid wooden wheels, and they were lighter and faster. The first spoked wheels were probably made for chariots.
Chariots with spoked wheels were light enough for horses to pull. Horses had been tamed for riding by about 3000 B.C. But they could not be used to pull heavy loads because a suitable harness had not yet been invented. The harnesses then in use pressed against a horse’s windpipe. If a load was too heavy, the harness hindered the animal’s breathing. However, two or more horses could pull a chariot easily. Horse-drawn chariots, used chiefly by rulers and warriors, became the swiftest vehicles of ancient times.
Ancient Greece.
During the 400’s B.C., Greece became the chief power in the Mediterranean area. The Greeks expanded the sea trade begun by the Phoenicians. They also pioneered in the building of two-masted vessels and increased the number of sails from one to four.
Greek cargo ships sailed from home with huge jars of olive oil and wine. Greek traders exchanged these products for wheat and other grains at ports on the Mediterranean and Black seas. The grain trade was extremely important to the Greeks. Wheat was the principal food during ancient times, and the Greeks had to import most of their supply.
The ancient Greeks developed a highly advanced civilization. Greek merchant ships helped spread Greek civilization westward. As civilization spread, trade and shipping increased. By 400 B.C., about 300 ports operated on the Mediterranean and several thousand trading ships of various countries crisscrossed the sea.
Ancient Rome.
From the 100’s B.C. to the A.D. 400’s, Rome ruled the mightiest empire of ancient times. At its peak, the Roman Empire included all the lands bordering the Mediterranean. It also extended as far north as Scotland and as far east as the Persian Gulf. To help hold their vast empire together, the Romans built a highly advanced system of roads. 
People had built roads long before Roman times. By about 1000 B.C., the Chinese had begun to construct roadways between their major cities. The Persians built a similar road network during the 500’s B.C. But most of the early intercity roads were little more than dirt tracks. The Romans constructed the first extensive system of paved roads. The best Roman roads were 16 to 20 feet (5 to 6 meters) wide and 3 to 6 feet (0.9 to 1.8 meters) thick. They had a base that consisted of several layers of crushed stone and gravel. The roads were paved with stone blocks.
The Romans used their roads chiefly to transport troops and military supplies. But the roads also served as an important communications link between Rome and its provinces. Messengers in horse-drawn carts used the roads to carry government communications. By the A.D. 200’s, more than 50,000 miles (80,000 kilometers) of paved roads connected Rome with almost every part of its empire.
During the 400’s, Germanic tribes gained control of the Roman territories in western Europe. The majority of Roman roads fell into ruin during the following centuries. However, a few are still used.
The Romans also built the largest fleet of cargo ships in ancient times. Like the Greeks, the Romans could not survive without sea trade. Roman cargo ships supplied the city of Rome with most of its grain.
The triangular lateen sail, which probably originated on Arab vessels called dhows, was in use in the Mediterranean Sea by around 200 A.D. Unlike square sails, which were widely used at the time, lateen sails could be positioned to work even when ships sailed into the wind.
The Middle Ages,
which lasted from about the A.D. 400’s through the 1400’s, brought great improvements in land and water transportation. These improvements resulted largely from three remarkable inventions—the rigid horse collar, the iron horseshoe, and the whiffletree. Scholars do not know exactly when or where all these devices were invented. But all three had appeared in Europe by the end of the 1000’s. 
The rigid horse collar appeared in Europe about 800, but was invented centuries earlier in China. Before this invention came into common use, horses wore a harness that fit across the neck. The harness choked a horse if it pulled a heavy load. The rigid horse collar shifted the weight of a load to a horse’s shoulders. Horses collared in this way could pull four or five times as much weight as before.
The iron horseshoe appeared in Europe about 900. Horses without shoes often suffered from damaged hoofs if they traveled long distances. Iron shoes protected a horse’s hoofs from damage and so enabled the animal to travel farther and faster than it could without them.
The whiffletree, which appeared during the 1000’s, made it possible for teams of horses to pull wagons. A whiffletree is a pivoted crossbar at the front of a wagon to which a team’s harnesses are fastened. It equalizes the pull of the horses. Without such a device, a wagon may be thrown off balance and may even be overturned.
The invention of the rigid horse collar, iron horseshoe, and whiffletree stimulated overland trade. These inventions made it possible for horses to pull as much weight as oxen—and for longer distances and at twice the speed.
The increased speeds of horse-drawn vehicles also encouraged greater use of wagons for passenger transportation. But wagon rides were extremely bumpy. Wagon makers tried to correct this problem by building vehicles with suspension systems, which provided a certain amount of cushioning against bumps. However, only rich people could afford such vehicles. Most of the people of the Middle Ages traveled on foot or on horseback, just as people had done in the past.
The design and construction of ships improved greatly during the Middle Ages. The first ships with a rudder rather than steering oars at the stern appeared in Europe about 1300. Rudders could be used to steer much bigger ships than could be steered with oars. During the 1400’s, shipbuilders began to produce ships four times as large as any built before. All these ships had a rudder, and most had three masts and at least three sails.
Several important navigation instruments were also developed during the Middle Ages. One such instrument, called a mariner’s compass, allowed voyagers to navigate their ships even when the sky was overcast and they could not use the positions of the moon, stars, and planets for navigation. By the late 1400’s, the advances in ship construction and navigation aids helped make long ocean voyages possible.
The age of overseas expansion.
During the late 1400’s and the early 1500’s, such European explorers as Christopher Columbus, Vasco da Gama, and Ferdinand Magellan made great ocean voyages. As a result of these and other voyages, European civilization spread to North and South America, India and the Far East, and later to Australia and New Zealand. However, this expansion of European culture took several hundred years. Despite the improvements in ship construction, ocean travel remained extremely slow.
Overseas trade began to increase rapidly during the 1600’s. Shipbuilders launched bigger and bigger cargo vessels to handle the growing trade. The larger ships had to have more sails, and the added sails helped increase speeds. By the mid-1800’s, the fastest merchant ships had as many as 35 sails and traveled at speeds up to 20 knots (nautical miles per hour). These vessels, called clipper ships, could sail from New York City, around South America, to San Francisco in three to four months. The overland journey from New York to California took twice as long as the voyage by clipper ship.
Development of inland transport.
By the 1600’s, most people used horse-drawn wagons to haul goods locally. But they seldom used wagons for long hauls because of the poor condition of the roads. Until the mid-1800’s, horse-drawn boats and barges were the chief means of long-distance inland transport. The animals trudged along the banks of rivers and canals and pulled the vessels with ropes.
Canal builders in Europe dug hundreds of canals from the late Middle Ages through the early 1800’s. The first canals in Britain (now the United Kingdom) were built to carry coal cheaply from mines to industrial towns. Canals also served as routes for transporting raw materials and finished goods. In this way, the canals contributed to the Industrial Revolution, a period of rapid industrialization that began in Britain in the 1700’s. The first major American canal, the Erie Canal, opened in New York in 1825. It connected Albany and Buffalo and provided a vital link in an all-water route between New York City and Great Lakes ports. Before the Erie Canal opened, the overland journey between Albany and Buffalo took about 20 days. The canal enabled horse-drawn barges to make the trip in 8 days. The success of the Erie Canal led to a great burst of canal building in the United States. By 1850, the United States had about 4,500 miles (7,200 kilometers) of canals. Canals, rivers, and other waterways carried most of the nation’s intercity freight.
During the 1700’s, France and Britain constructed the first well-built paved roads since Roman times. By the mid-1800’s, the first major United States highway, the National Road, had been completed. The highway connected Cumberland, Maryland, and Vandalia, Illinois. It was a gravel road and inferior to the best French and British roads of the time. American pioneers traveling west from the Mississippi River crossed a wilderness without roads. They drove their covered wagons along well-traveled dirt paths, such as the Santa Fe Trail and the Oregon Trail.
The basic design of wagons and coaches changed little from the late Middle Ages through the 1800’s. The first city coach line started in Paris during the 1660’s. It was the ancestor of today’s public transportation systems. The first long intercity coach line began service between England and Scotland about 1670. The line operated between the cities of London and Edinburgh, a distance of 392 miles (631 kilometers). The coaches were called stagecoaches because they traveled in stages, stopping at scheduled places on a route for changes of horses. The first stagecoach lines in the American Colonies began service during the 1730’s.
The steam age.
The invention of the steam engine marked the beginning of the greatest revolution in transportation since the invention of the wheel and the sailboat. British inventors developed the steam engine during the 1700’s. Nicolas-Joseph Cugnot, a French military engineer, built the first self-propelled road vehicle, which was powered by a steam engine, in 1769. In 1807, the first commercially successful steamboat service started in the United States. By the late 1800’s, ships powered by steam engines were rapidly taking the place of sailing ships on the world’s shipping lanes. 
The world’s first successful steam railroad went into service in the United Kingdom in 1825. Steam-powered trains played the leading role in the transportation revolution. By the 1840’s, the spread of railroads caused canal traffic to decline. Rail service provided faster transportation of goods and a greater number of routes than canals. By the late 1800’s, some steam locomotives traveled at speeds of more than 60 mph (100 kph). They could haul loads hundreds of times heavier than a team of horses could pull. By 1900, rail lines had been built throughout Europe and North America and in many parts of Africa, Asia, Australia, and South America. The overland journey by train from New York City to San Francisco took less than a week. In comparison, the trip took weeks or months by stagecoach or by covered wagon.
As more and more steamships and steam-powered trains went into service, passenger fares and freight rates dropped. The lower costs encouraged travel, trade, and the growth of cities. In addition, many people became accustomed to fast movement and rapid change. The quickening pace of life created a demand for still faster transportation.
The beginnings of modern transportation.
In the mid 1860’s, workers in the shop of Pierre Michaux, a French blacksmith, added pedals to a scooterlike vehicle called a draisine, creating the first confirmed bicycle. The first electric trains and streetcars appeared in Europe and the United States during the 1880’s. In the 1890’s, the German engineer Rudolf Diesel invented the engine that was later named after him. In time, diesel engines replaced steam engines on many ships and on most trains. But of all the inventions of the 1800’s, the gasoline engine was the one that brought about the most far-reaching changes in transportation.
German inventors built the first successful four-stroke gasoline engines during the 1880’s and used them to power bicycles, boats, and carriages. During the 1890’s, French engineers built the first gasoline-powered vehicles with automobile bodies. The first gasoline-powered buses and trucks were built in Germany during the 1890’s. In 1903, two American bicycle makers, Orville and Wilbur Wright, used a gasoline engine to power a small airplane that they had built. The Wright brothers’ plane became the first one to lift a person into the air and fly successfully. Loading the player...
First successful airplane flight
Automobiles became the chief means of passenger transportation in many industrialized countries during the 1920’s. As the number of automobile owners increased, so did the demand for more and better roads. The industrialized countries built many new roads between 1900 and 1930. In the United States, about 700,000 miles (1,100,000 kilometers) of surfaced streets and highways were built during this period.
The first commercial airlines began service in Europe in 1919. Airlines began operations in many other parts of the world during the 1920’s. By the late 1930’s, the world’s airlines carried 31/2 million passengers annually. All airplanes had propellers and gasoline engines. During the late 1930’s, German engineers built the first planes with jet engines. All the early jet aircraft were warplanes. The first jet airliners began service during the 1950’s. 
The great advances in transportation during the 1900’s brought about enormous changes in people’s lives. The development of commercial air travel made long journeys routine. As a result of improvements in ocean shipping and in refrigeration, goods that were once available only in certain regions began to be distributed worldwide. The development of the automobile led to the growth of suburbs around big cities. Most suburbanites depend on their cars for shopping and other personal business. They may also use their cars to get to and from work in the central cities. Without this convenient means of private transportation, suburban living would be impractical or impossible for many people.
Transportation today
Before the development of engine-powered vehicles, nearly all transportation involved the shipment of goods. Passenger transportation was relatively uncommon. The development of engine-powered transportation changed this situation dramatically. Today, passenger transportation is an essential part of everyday life in industrialized countries. Workers in these countries live much farther from their places of employment than workers did in the past. As a result, they need quick, dependable transportation each workday. Many children need transportation to and from school. Families depend on transportation for shopping and other errands. Many people travel long distances on vacations. In some industrialized countries, more money is spent on the various means of passenger transportation than on the shipment of freight. 
This section deals mainly with engine-powered passenger and freight transportation in industrialized countries. In rural areas of developing countries, many people still rely on age-old transportation methods. 
Passenger transportation
includes both private and public transportation. People who use private transportation operate their own vehicles. Those who use public transportation pay to ride on vehicles owned and operated by private companies or by the government. The three main types of public transportation service are urban, intercity, and overseas.
Private transportation
in industrial countries is provided mainly by automobiles, bicycles, motorcycles, and private airplanes. Automobiles are by far the most important means of private transportation.
In large industrialized countries, such as Australia, Canada, and the United States, most people travel chiefly by car. People in such countries use their cars largely for local transportation. But automobiles are also the leading means of travel between cities. Automobiles are also the chief means of passenger transportation in smaller industrialized countries, such as Japan, New Zealand, and most of the nations of Western Europe. People in these automobile-using countries own about half of the world’s cars. The countries with the most automobiles also have the best road systems.
Highway travel is far less important in developing countries than in developed ones. But a growing number of city dwellers in developing countries own a car. The biggest cities have had to build more expressways to handle the ever-increasing flow of automobile traffic. 
Urban public transportation.
Most large urban areas provide some means of public transportation for people who do not own a car or who prefer to avoid city driving whenever possible. Public transportation in urban areas is called mass transit. Mass transit between cities and suburbs is often called commuter service. Commuter trains are the chief means of public transportation between big cities and their suburbs.
Buses are the chief means of transportation in most of the world’s cities. Most cities with mass transit systems offer only bus service. However, a majority of the world’s largest cities also offer rail service. Many major cities have both subway and surface rail lines. Some also have elevated trains, which run on tracks above the streets. 
A growing number of large cities have light rail vehicles. A light rail vehicle is an electrically powered railway car that gets its power from an overhead trolley wire or an electrified third rail. Streetcars, called trams in some regions, are a type of light rail vehicle. During the late 1800’s and early 1900’s, streetcars were an important part of the mass transit systems of many cities. Most streetcar tracks ran down the middle of the street, and increasing automobile traffic began to interfere with the operation of the streetcars. During the mid-1900’s, buses replaced streetcars in many cities.
Today’s light rail vehicles can run underground, on elevated tracks, or on tracks built alongside city streets. The cars can travel individually, or they may be linked together to form a train. The wheels of many light rail vehicles have metal wheels built over a rubber core, enabling these vehicles to run more smoothly and quietly than other trains.
Another type of mass transit facility is the people mover. People movers carry passengers along specially constructed guideways in driverless, electrically powered cars. Most people movers operate over short distances in such places as parks and airports, but a few serve the downtown areas of cities.
Most cities today cannot afford to build extensive new mass transit facilities. But many cities are trying to improve their existing facilities. For example, a number of cities have speeded up bus service by reserving certain traffic lanes for buses only. Some experts believe that electrically powered light rail systems can help improve mass transit in many cities. Such systems cost less to build than subways, and they run more quietly and smoothly. Unlike buses, they produce no exhaust fumes.
Intercity public transportation
is provided mainly by airplanes, buses, and trains. Riverboats and ferryboats carry an extremely small share of intercity passengers. 
In some industrialized countries, such as Australia and the United States, airlines handle a large proportion of intercity passengers on long trips. However, automobiles, buses, and trains are the preferred means of transportation for many people, particularly for short trips. In China and India, and most of Africa, railways and buses carry more passengers than automobiles or airplanes. Railroads and buses are the chief modern means of intercity travel in most developing nations. Many countries have high-speed passenger trains. Short-range airliners play an important part in intercity transportation in Europe.
Most industrialized countries seek to improve passenger service on major intercity rail routes. High-speed electric trains provide swift intercity service in Japan, South Korea, the United States, and several European countries, including France, Italy, and the United Kingdom. Japan’s “bullet train” links cities on the islands of Honshu and Kyushu. The French TGV (train à grande vitesse, or high-speed train) connects Paris with several other cities in France and with cities in Belgium. The fastest of these trains can operate at around 200 miles (320 kilometers) per hour.
High-speed trains can compete with airliners for passengers on journeys of up to about 500 miles (800 kilometers). Most big airports are on the outskirts of large cities. For short- and medium-length flights, the trip to and from the airport may take longer than the flight itself. Trains, on the other hand, usually take passengers all the way to stations in the centers of cities. Passengers on a high-speed train may thus complete their entire journey in less time than it would take by air.
Engineers are developing a type of high-speed passenger train called a magnetic levitation train or maglev train. The track for maglev trains consists of a single guideway, which the vehicle straddles but does not touch when in motion. Electromagnetic forces lift the train above the track and propel it forward. In tests and demonstrations, maglev trains have exceeded 370 mph (600 kph). But few maglev train systems operate commercially. Because maglev trains cannot run on conventional train tracks, entirely new rail networks must be built for them. Maglev train systems are in development in many parts of the world. See Magnetic levitation train.
Overseas public transportation.
The first overseas airlines began operations during the 1930’s. But the planes had to stop frequently during a flight for refueling. Most overseas travelers continued to go by ship until the late 1950’s, even though it took much longer to sail than to fly. The voyage across the Atlantic Ocean, for example, took four days or more. The first nonstop transoceanic airliners appeared during the late 1940’s. These propeller-driven planes could carry passengers across the Atlantic in hours rather than days. As these planes became more common, overseas travel increased. The first transoceanic jet airliners began service during the 1950’s, leading to a tremendous increase in overseas travel.
Today, almost all overseas travelers go by plane. Only one ocean liner, the Queen Mary 2, provides regular transatlantic passenger service. Most ocean liners today operate as cruise ships. They specialize in taking vacation travelers to such popular destinations as Alaska, the Caribbean, and the Mediterranean.
Freight transportation.
Pipelines provide the cheapest means of transporting petroleum and natural gas. The cheapest way to move general cargo is by water. Rail transportation costs about 3 times as much as water transportation, and truck transportation costs about 10 times as much. Air transportation costs nearly 40 times as much as water transportation. Because air transportation is so costly, cargo planes usually carry only expensive, lightweight, or perishable merchandise. 
The various means of moving cargo are used for both (1) domestic freight and (2) international freight.
Domestic freight.
Most domestic freight traffic involves the transport of cargo between cities within a country. Airplanes, barges, pipelines, railroads, ships, and trucks carry the cargo. Freight shipments within cities consist mainly of pickups and deliveries. Trucks carry nearly all such local freight. 
In industrialized countries, rail shipments account for about half of the freight hauled. Shipments by truck account for about one-quarter. Petroleum pipelines and barges and ships carry smaller fractions of the freight, and airplanes, only a tiny amount. Railroads carry a greater share of the intercity traffic in European countries than in the United States. Canal traffic is also greater in Europe.
In many cases, a particular freight shipment must be switched from one type of carrier to one or more other types to reach its destination. For example, many coal shipments travel by train, barge, and truck on their way to the buyer. The movement of freight by more than one method is called intermodal transport.
One common type of intermodal transport is known as containerization. Freight is packed into large crates called containers. The containers are designed to ride on truck trailers and railroad flatcars. They can easily be transferred between the two types of carriers and to specially designed container ships.
Containerization is used mainly to transport such goods as machinery and household appliances. The method reduces shipping costs, speeds deliveries, and cuts losses due to breakage. Some domestic freight is containerized. But containerization is used mainly in international trade. 
International freight
is transported mainly by ships. Many of today’s merchant ships are designed to carry containers or a particular kind of cargo, such as petroleum, grain, or iron ore. In many cases, the ships require specialized port facilities. Most large ports have been equipped to handle containers. Giant cranes and other lifting devices transfer the containers between container ships and truck trailers or railroad flatcars. Some of the world’s busiest seaports specialize in handling oil tanker traffic. These ports have exceptionally deep harbors to accommodate giant tankers. They also have pumping systems and pipelines for loading and unloading the oil.
Some international freight moves by highway, rail, pipeline, inland waterway, or airplane. The countries of Europe, especially, depend on these methods in their trade with one another.
The transportation industry
Transportation is one of the leading industries in the world. Many of the world’s biggest industrial firms earn all or much of their income from the sale of equipment or fuel for transportation. The transportation industry employs many millions of people throughout the world.
The transportation industry consists of (1) equipment manufacturers, (2) passenger and freight carriers, and (3) related industries. The equipment manufacturers and passenger and freight carriers are the key organizations. However, the related industries play a vital role in transportation by providing fuel and various services and facilities. Governments throughout the world are also involved in transportation, though the extent of involvement varies from country to country.
Equipment manufacturers
produce the vehicles necessary for modern transportation. They also supply the equipment needed to operate the vehicles. This equipment includes railroad tracks, airplane communications systems, replacement parts, and maintenance equipment.
Companies that make automobiles, buses, and trucks are by far the largest producers of transportation equipment. Leading producers of motor vehicles include Honda Motor, Nissan Motor, and Toyota Motor of Japan; Daimler AG and Volkswagen of Germany; Fiat of Italy; and General Motors and Ford Motor of the United States.
Passenger and freight carriers
include airlines, intercity bus lines, mass transit companies, pipeline companies, railroads, shipping lines, and trucking firms. In most countries, the central government owns and operates the airlines and railroads and some or all of the intercity bus lines. The United States and Canada are chief exceptions. Private companies own and operate all the airlines and intercity bus lines, and nearly all the railroads in the United States and Canada.
In some countries, the central government owns the intercity bus lines, pipelines, and shipping and trucking lines. In other countries, these services are provided by privately owned firms, which are subject to various forms of government regulation. In nearly every country, local governments control all or most mass transit services.
Related industries
include glass, petroleum, steel, and tire production; road construction; the selling of new and used cars; and the servicing of automobiles and other vehicles. Petroleum production is the leading transportation-related industry in terms of value. Several of the world’s largest manufacturing companies are oil companies.
Government and transportation.
Governments are most deeply involved in transportation in those countries where all or much of the industry is publicly owned. But even in countries in which nearly all transportation companies are privately owned, government plays a major role in the transportation industry. This role consists primarily of (1) providing funds for transportation facilities and (2) regulating transportation.
Government funding.
Four kinds of transportation facilities depend almost entirely on public funds. They are (1) air traffic control centers, (2) airports, (3) public roads, and (4) river and harbor facilities. Far more money is spent on the building and upkeep of roads than is spent on the other three facilities put together. Funding for large airports, roads, and river and harbor facilities can come from local, regional, or national governments. Funds for projects in developing countries usually come from international lending bodies, such as the World Bank, or from foreign governments. National governments usually finance air traffic control operations. 
Mass transit systems in most countries depend heavily on government financial support. Few of the systems earn enough from passenger fares to pay all their expenses.
Government regulation
deals chiefly with transportation safety, the emission of pollutants by vehicle engines, fuel economy, and the business practices of transportation companies. Governments throughout the world establish safety rules for the various methods of transportation. Governments also set and enforce standards for vehicle emissions and regulate the business practices of transportation companies.
Challenges of modern transportation
Modern transportation poses many challenges, including (1) traffic safety, (2) overcrowding of streets and highways, (3) declining fuel reserves, (4) environmental problems, (5) inadequate public transportation facilities, and (6) transportation security. These challenges are most severe in countries that depend heavily on automobile transportation.
Traffic safety.
The use of most types of high-speed, engine-powered transportation involves traffic safety problems. In some countries, including the United States, more people are killed in automobile accidents every year than in all other transportation accidents combined. Most automobile accidents could be prevented if every driver obeyed all traffic laws and all the rules for safe driving.
Airlines have one of the best safety records in the field of transportation. But heavy air traffic at major airports has increased the hazards of commercial flying. When many airliners await clearance to land or take off, airport approaches and runways can become dangerously overcrowded. In addition, large airports have an ever-increasing amount of private plane traffic, which makes traffic control even more difficult.
Railroads are generally a safe means of transportation. Train collisions and derailments are rare, but they may occur on busy lines when signaling equipment fails or when track is worn or damaged. Railroad companies have track replacement programs, and they routinely check signaling equipment.
Overcrowding of streets and highways.
Traffic congestion (overcrowding) on streets and highways increases transportation times and can also make driving more dangerous. Scientists and engineers are developing intelligent transportation systems to deal with congestion. One development, an electronic toll system, automatically identifies vehicles and charges their owners or drivers for the use of roadways and bridges. Electronic toll systems eliminate waiting at toll booths and reduce the cost of collecting tolls. In Hong Kong, China, tolls are charged electronically on vehicles using congested city streets. Other applications of intelligent transportation systems include automatic tracking of vehicles and rapid identification of accidents. 
Declining fuel reserves.
Gasoline and other fuels made from petroleum supply nearly all the energy for engine-powered transportation. Energy experts warn that the world’s supply of petroleum is being used up rapidly.
Industrialized nations must ensure that all their major transportation systems have enough fuel to function normally. But they must also do all they can to conserve fuel. Fuel conservation is necessary not only because of the threat of a serious fuel shortage but also because of the high price of petroleum and the environmental damage caused by the burning of many transportation fuels. Higher petroleum prices result in higher transportation costs, which drive up the prices of transported goods.
Automobiles consume more than half the energy used for transportation in industrialized countries. They therefore contribute heavily to energy supply problems. To help reduce automobile fuel consumption, governments set fuel consumption standards for new cars. These standards encourage automakers to produce smaller, lighter cars, which travel farther per gallon or liter of gasoline than larger models.
Beginning in the 1960’s, automakers also began to develop modern electric cars. Fully electric cars do not use liquid fuel or produce exhaust. Instead of a gasoline engine, they have one or more electric motors. These electric motors are powered by a rechargeable battery. In the early 2000’s, automobile manufacturers first made hybrid electric vehicles available to consumers. Hybrids combine an electric motor with another power source, usually a gasoline engine. They provide better fuel economy than comparably sized vehicles with gasoline engines. 
Eventually, however, the transportation industry almost certainly will need substitutes for low-cost petroleum fuels. Energy companies are already producing synthetic liquid fuels from coal, natural gas, biomass, oil shale (a rock containing kerogen, a substance that yields oil when heated), and bituminous sands (sands containing bitumen, a substance from which oil can be obtained). A company in South Africa, for example, makes gasoline from coal. Companies in Brazil make ethanol, also called ethyl alcohol, from sugar cane pulp, and U.S. companies produce the fuel from corn.
Environmental problems.
The production, transportation, and use of transportation fuels all affect the environment. The drilling of offshore oil fields and the shipment of petroleum by tankers sometimes result in oil spills that pollute the ocean and kill wildlife. Motor-vehicle exhausts rank as a leading source of air pollution. The major pollutants produced by motor vehicles include carbon monoxide, hydrocarbons (compounds of carbon and hydrogen), and nitrogen oxides (compounds of nitrogen and oxygen). Nitrogen oxides can react with hydrocarbons in the presence of sunlight to produce a form of oxygen called ozone. Ozone is the chief component of photochemical smog, which is a common form of air pollution.
Even the cleanest fuels produce carbon dioxide when they burn. This gas slows the escape of heat released by Earth into space. Thus, an increase in atmospheric carbon dioxide may cause global warming.
Automobiles are the chief cause of traffic congestion in urban areas, and their exhaust fumes contribute heavily to urban air pollution. Many cities plagued by traffic jams and air pollution have taken steps to reduce automobile traffic in their busiest areas. Governments have established ever stricter pollution-control standards for new cars. These standards require automakers to manufacture cars that give off cleaner exhausts than earlier models.
Inadequate public transportation facilities.
Greater use of public transportation in many countries would help ease problems caused by heavy dependence on automobiles. But public transportation in many areas must be improved before more automobile drivers can be persuaded to use it.
Transportation security
is a continuing concern. A bomb detonated aboard a vehicle can cause great damage not only to the vehicle and its passengers but also to vehicles, structures, and people in the surrounding area. Hijackers may also seek to seize control of a vehicle and cause a collision. Such a collision, especially if it involves a heavy vehicle traveling at high speed, can cause considerable damage. In addition, spilled fuel provides significant fire risk after such a collision.
On Sept. 11, 2001, terrorists crashed hijacked airliners into the World Trade Center in New York City and the Pentagon Building near Washington, D.C. Soon afterward, the U.S. government formed the Transportation Security Administration. This agency works to prevent criminal acts involving aircraft, airports, bridges, highways, pipelines, ports, and railroads in the United States. Security personnel at airports search travelers, baggage, and freight for bombs or hand weapons. Other transportation systems take similar precautions. For example, some railroads employ specially trained dogs that sniff checked baggage for hidden explosives.
