New York — The enormity of New York City's mass transportation system is almost mind boggling. One of every three Americans who uses public transportation each day does so here. The buses, trains, and subways of the Metropolitan Transit Authority carry 5.6 million riders daily, according to MTA figures. And 673,000 more come over the bridges and tunnels that are also under the MTA's umbrella.
The system has numerous problems. There are frequent breakdowns and delays. Safety and crime are constant concerns with riders of the graffiti-covered cars. Already high fares are expected to climb even higher. And those running the system are captive to the annual race for local, state, and federal funds.
Enter Robert R. Kiley, former head of the Boston transit system, who was recently appointed chairman of the MTA by New York Gov. Mario M. Cuomo. As he familiarizes himself with the job and the city, he is taking a hard look at the future.
''There is not a master plan for MTA planning. No one has really said where we will be in the year 2000. And it is not pie- in-the-sky to look at the 21st century.''
During his first week on the job, Mr. Kiley admits there is no lack of priorities, though he estimates it will take him several months to get to know the system. But he sees five areas that he must tackle immediately:
* Finding a new head for the New York City Transit Authority, which operates the buses and subways in the city's five boroughs.
* Getting a good handle on the system's finances.
* Listening to what commuters says about transportation in the region.
* Planning for the future.
* Developing a strong management team at the MTA headquarters.
And he is concerned about how the people down there feel about the trains, buses, and subways.
''Not too red hot,'' admits Kiley, who planned to ride the system for some four hours later that evening. Service in some areas has improved, he says.
But the systems, particularly in the city, have been in decay and decline for many years, and demographic and socioeconomic changes have made vast differences in what sort of services are needed.
One problem that stands out on the subways is crime, he says. And the appearance of graffiti-covered cars is closely linked to how safe riders feel.
''When people see it, there is an immediate sense of a mysterious hand out of control. It is a powerful negative feeling, and there is no simple solution,'' Kiley says.
He will make a strong effort to keep the cars clean. The first of some 1,375 stainless steel subway cars began test service Tuesday. Their surface resists graffitti.
The cars were attained through a capital spending program set in place by Richard Ravitch, the past MTA chief. The $8.5 billion five-year program is a legacy that must not be squandered, says Kiley. It is being used for such things as repairs, maintenance, and new cars for both subways and trains. Some of the money will also be used for an MTA human-resources development program.
Kiley wants to make sure the money is spent on sensible, urgent programs, and that a spending is monitored properly.
Future funding is also very high on Kiley's list. One estimate, which he says he can't verify, claims the system needs $1 billion a year to remain viable. As chairman of the MTA, Kiley will spend much time courting government, unions, and the public to get support for the system. He has already said he would like more state funding to operate his fleet.
Kiley would like a broad coalition to look at the MTA's future, perhaps a blue-ribbon task force.
New York has changed a lot since the subways were first put into service in 1904. He would like to explore current trends in service. Who uses the system? What is a fair price? Who should support it financially?
Should some lines be terminated? Which are underserviced? What relationship does the transit system have to the 21st-century economy?
The most immediate task he faces is to find a Transit Authority president.
''He or she has got to have a pretty good understanding of the system,'' he says. Kiley talks about ''civility,'' ''consciously trying to serve the public, '' and ''spirit-building'' in reference to a new Transit Authority president.
Kiley's predecessor Richard Ravitch received good marks from many observers. Most say he did an excellent job setting up a more promising financial system for Kiley to run with.
''Now Kiley has to be an operator,'' says one city official.
After his four-year term is completed in 1987, Kiley says he would like to ''believe the system is being led by very able, strong managers who have established and accomplished goals. I want those using the system to sense movement forward.''