1. Paratransit
Paratransit includes a variety of local services like taxis, dial-a-ride buses, van and car pools, taxis or small buses along fixed routes (jitneys), short-term vehicle rentals, and other demand-paced services. The systems are designed to be flexible in their routes and schedules. They require relatively low investment and may enable their customers to save at least one automobile per family. They somewhat reduce general traffic congestion, though they still contribute to it by using the public streets, including major arteries. The disadvantages of most paratransit systems include high labor costs, possible difficulties in enforcing reliability, security problems in some systems, and usually low overall capacity.
2. Buses
Bus systems account for a high percentage of all transit vehicles in the United States. They are flexible in schedules and routes and can detour around trouble spots when needed. Buses, however, require higher volume than paratransit. Though the technology for building clean, quiet buses exists, buses can be noisy and polluting. These problems are sometimes the result of poor maintenance. Some design problems—such as access for those with disabilities and for speedy loading and unloading—have been met. Other disadvantages are high labor costs, even at high volume, and susceptibility to delay from other vehicles. Reserved bus lanes have been established on some major highways in several cities; however, these lanes reduce the total road space available. This disadvantage is what buses were originally intended to overcome.
3. Light Rail
Light rail includes trolley cars, streetcars, trams, and tramways. They operate at ground level or as aerial structures. These vehicles have the advantage of being quiet and, depending on location of right of way, potentially fast. They use electric traction and thus are potentially independent of petroleum-based fuels. Right-of-way capacity is high, and labor can be reduced by using multicar trains. The systems can be made more appealing to the eye by burying the track under a grassy surface—only the tops of the rails then are visible. Disadvantages include substantial costs of fixed plant, fixed routing, and the necessity of sizable traffic volumes. Light rail systems in such cities as Baltimore, Minneapolis, and Sacramento experienced growth in passenger ridership of more than 15% in 2008. Many cities in Europe and Japan have successful light-rail systems.
4. People Movers
This mode encompasses a variety of automated systems in which automated vehicles move on fixed guideways along a fixed right of way. Such systems exist in the United States at airports, zoos, or amusement parks. They are also used in some downtown districts. They include monorails; several of them resemble horizontal elevators in which the destination buttons are pressed by the passengers. A number of the systems have experienced considerable operating troubles. An allied set of systems consists of passenger conveyors (such as moving sidewalks) and escalators, including those in which three or more conveyors move side by side. This arrangement permits relative increases in speed.
5. Heavy Rail Local Service
These are subways, the diminishing elevated lines, and commuter railroads. They include several very old established systems as well as new ones. In the United States the old ones are mainly in New York, Chicago, Boston, and Philadelphia. New networks have been completed or are under construction in other cities. Substantial new systems also have been constructed or extended around the world. For example, a new subway was built in Beijing in time for the 2008 Olympic Games. Attempts have been made in the new systems to integrate them with existing facilities. Technological changes, however, have made this difficult in many cases.
6. Corridor Rail Service
This is mostly rail service for distances up to 250 miles (400 km) or more. To operate properly, it requires railroad lines capable of very high speeds, upward of 100 miles (160 km) per hour. The technology for this is generally available; electric traction is used by most of the systems. Many states have focused on rail corridor development as a means of improving access to city centers. Corridor services of Amtrak, the public U.S. rail-passenger service, serve 23 states. They operate over a 6,000-mile (9,660-km) route system. The Northeast Corridor (Washington–Boston) is North America’s busiest railroad. Some 2,600 trains operate over a portion of the route daily. Amtrak’s other busiest U.S. corridors include California's Pacific Surfliner, which covers San Diego, Los Angeles, and San Luis Obispo; Capitol (San Jose–Oakland–Sacramento–Auburn); Empire (New York–Albany–Buffalo–Toronto); Keystone (New York–Philadelphia–Harrisburg); and San Joaquin (Oakland–Fresno–Bakersfield).
The high-speed Acela Express service in the Northeast Corridor travels between Washington, D.C., and New York in less than 3 hours. It can traverse Washington to Boston in approximately 3 hours and 30 minutes. Other lines have invested funds to improve service and trip times.
Substantial progress in corridor service has been made in Japan and Europe. The famous Japanese Tokaido "Bullet Train" line, in commercial service since 1964, is still one of the fastest and most successful lines in the world. It serves the Tokyo–Osaka corridor at a top cruising speed of 130 miles (210 km) per hour. Extensions of the system go south to the island of Kyushu; they extend northward from Tokyo. The French TGV (Train à Grande Vitesse) connects Paris with southeastern France at speeds up to 180 miles (290 km) per hour. Its fuel consumption per passenger-mile is about one-fifth that of airliners. Other new notable lines have been built in Germany and Italy. In some cases, rather than lay new tracks, existing tracks have been upgraded. The "Intercity" services of the major European rail systems are corridor services and have shown themselves highly (and increasingly) competitive with air travel, not only in cost but also in center-to-center time. Africa’s first high-speed train, Gautrain, began operation in 2010. It initially connected uptown Johannesburg, South Africa, with the nation’s major airport, located outside the city. It opened in time for soccer’s 2010 World Cup, hosted by South Africa.
The main problems of corridor systems are extremely high costs and fixed routing. If, however, transfers to local services are well organized, corridor systems have great potential for serving enormous numbers of people.
