单项选择题

TEXT C
Since about 1950, public transportation in the U.S. has had to struggle to survive. The growth of private automobile ownership, the change in cities with accelerated urban sprawl, and the immense highway construction program have added to transit problems. Moreover, changes in life-style have contributed to reduced transit use, which has resulted in lower revenues from fares at a time when costs for operations have increased greatly.
As private transit systems were taken over by local government and the cost of operations continued to increase, pressure was exerted for federal participation in urban public transportation. The 1964 Urban Mass Transportation Act established this commitment. The legislation limited federal assistance to 80 percent of the capital expenditure for buses, rail cars, and fixed facilities. In 1974 the federal government added operating assistance to its program. Because passenger fares account for only about one-third of the average system’ s operating funds, demand for federal subsidies escalated rapidly. In the early 1980s a change in federal transportation policy resulted in relaxation of the rigid standards governing the way federal aid is used, imposing requirements for private sector participation and increased state, regional, and local funding. By the end of the 1980s state and local operating assistance amounted to about 2 percent of the funds needed to operate U.S. transit systems; fare box and other revenues accounted for 43 percent, and federal assistance, 5 percent.
Private sector initiatives in public transportation include transit services provided by private operators under competitively bid contracts, and innovative public-private projects such as a joint development of transit stations.
It is estimated that 8 million people in the U.S. (5 percent of the urban population) have physical handicaps that prevent them from using conventional transportation services. With the aging of the population, more than one-fifth of the people living in the U.S. will be over 65 in the year 2030. Many of the people in these groups are dependent on public transportation. In 1990 Congress passed the Americans with Disabilities Act, which will virtually require all transit services to be accessible to the disabled.
In the short run, existing transit modes will be improved. Cities with such systems will extend their lines, while others will plan and construct new ones, including rapid transit, buses, and light rail transit. The lower- cost alternatives will have a better chance of adoption. There is also a strong interest in commuter rail. Part of the appeal of this mode of transportation is that many cities have unused and underused rail corridors that can provide rights-of-way at low cost.
Because of major environmental concerns, electric trolley buses and methanol-powered and other alter- native fuel-powered buses will replace diesel engine buses.
An enormous range of new technology exists in the area of intelligent vehicle systems. For example, a commuter will be able to get real-time information on home computers as to when the next bus will arrive at the nearest bus stop. Information for trip planning will be available as well. Transit agencies will use advanced technologies for traffic and fleet management of their vehicles. Vehicle control systems that will guide buses along prescribed corridors and routes are being researched to reduce vehicle delay, increase capacity, and improve safety.
Automation through new technology can provide a means for reducing labor while providing performance and safety. A number of automated guideway transit systems operate in airports, shopping centers, college campuses, and amusement parks. Their applicability to a more diverse use is continually evaluated. Research is under way on magnetically levitated and air-supported vehicles. Directional control, spacing, switching, and lateral control are among the many problems needing more development before such systems can be widely accepted. Other developments include the moving walkway, designed mainly for short distance, which will accelerate a pedestrian from three to five times walking speed.
Unique structural systems have been designed to support advanced transit concepts. Suspended mono- rails are examples of lower-cost systems under development.
The first two paragraphs want to tell us______.