PROVIDENCE — Short of money and expecting continued deterioration of its finances, the state’s transit system is considering a broad cut in service just as high gasoline prices are pushing people out of their cars and onto buses.

The service cuts, which would go into effect in December, would eliminate or reduce service on more than 160 bus lines or sections of lines to save $9.7 million per year, and Rhode Island Public Transit Authority officials say that more cuts are likely to cover growing budget deficits. The cuts described are already large, amounting to about 10 percent of the authority’s budget for next year.

The apparently bizarre situation — the prospect of cutting bus service just when increasing ridership and rising gasoline prices suggest that more service is needed — grows out of the way the authority is financed. It relies heavily on revenue from the state gasoline tax. But as people buy less gas, that revenue stream is dropping at the same time the authority is suffering from a dramatic run-up in one of its biggest expenses, diesel fuel.

The plan largely involves three kinds of service reductions: the elimination of some routes entirely, the elimination of sections of routes, for example stopping routes that now serve the suburbs at the Providence city line, and the elimination of evening service on many routes. Some buses would also run less frequently. The authority is also looking into ending free service for some elderly and disabled persons, who would instead pay 85 cents per ride, about half fare. That would require action by the governor and General Assembly.

RIPTA Planning Manager Tim McCormick said the agency staff used four criteria — the number of passengers per trip, per hour, and per mile and the amount of fares collected — to rank the routes and identify those whose reduction or elimination would have the least impact. He said RIPTA is also trying to eliminate duplicative service first, and to preserve trips to work and to hospitals and medical centers.

He said it is difficult to protect trips to work because practically all of the bus routes take people to work. The plan would eliminate service after 7 p.m. on weeknights on 27 routes, but McCormick said, “Most of the people using the system at night are working.”

At this point, the plan is a staff recommendation to the authority’s board of directors, which has taken no action on it.

However, when the subject came up at the board’s last meeting, Vice Chairman John Rupp said, “We’re going to have to look at service cuts.”

The service reduction plan arrives along with a novel political situation. After failing ever since he was elected to gain a majority on the RIPTA board, Governor Carcieri saw his appointees take control in April, unceremoniously ousting Providence City Planning Director Thomas Deller from the chairmanship and installing Robert D. Batting, a retired business executive and Carcieri appointee, in his place. That leaves the governor’s appointees to deal with RIPTA’s intensifying financial problems.

The governor didn’t offer much hope of financial support in a statement Thursday. While he supports RIPTA’s “core mission,” Carcieri said, “RIPTA needs to see fully the challenges of doing more or even the same with less.”

The service cuts contained in the plan may be just the beginning. They would save an estimated $9.7 million per year, but because they would go into effect in December, about half way through the agency’s fiscal year, they would save only about half that amount during the year. That’s less than the $7.5 million in deficits RIPTA is expecting.

McCormick said the service cuts may also have to grow larger to cover costs not yet counted, for example unemployment compensation if the authority has to lay off employees.

There is, meanwhile, no sign of additional money to cover the expected budget gaps. Last Monday, the board voted to ask for an additional $3-million slice of revenue from the gasoline tax, money which now goes into the state’s general fund. But officials said that they aren’t expecting anything to come of it because of the state government’s own budget problems and competition from other agencies.

As the plan stands now, it would eliminate six routes and shorten one because they, to some extent, duplicate other service. Riders would have to walk to the closest line. The 66, 61, 11, 80, 53 and 49 buses would be eliminated, and the 55 Bus would stop at the Providence city line.

Some apparent duplications have a history. The 8 Bus, for instance, goes down Jefferson Boulevard in Warwick, and the 20 Bus takes a parallel route down Post Road not far away. The Amtrak rail line runs between Post Road and Jefferson Boulevard, where there are employers including a Citizens Bank call center.

McCormick said the Bus 8 line was created because Amtrak officials complained that workers were running across the tracks from the Post Road bus to get to work. The 8 Bus would be eliminated.

And 10 additional routes would be either eliminated or lose their Saturday or Sunday service because the ranking system also showed them to be “low performing.” Among the routes eliminated would be the 64 Bus, which connects the University of Rhode Island with Newport through North Kingstown and Jamestown, and the 62 Bus from downtown Newport to Fort Adams and the Block Island ferry.

A further 11 segments of routes would be eliminated or have buses pass less often. Four of those routes, the 1, 27, 28 and 57 buses, which now serve parts of Cranston, Warwick, North Providence and Johnston, would stop at the Providence city line instead.

RIPTA has had years of financial crises, in large part because the gasoline tax, a flat 30 cents per gallon, produces additional revenue only if the number of gallons sold increases. Meanwhile, RIPTA’s costs, like everybody else’s, rise. That has been especially true with fuel.

The authority had budgeted $6.3 million for diesel fuel during the fiscal year that ended last Monday, and General Manager Alfred J. Moscola said that until March, the budget was balanced. But between then and June 30, fuel cost increases were largely responsible for a $1.8 million deficit. RIPTA carried that deficit over to the current fiscal year, when it expects to run up a $5.7 million deficit, largely for the same reason, unless it cuts spending and service.

The last time RIPTA considered serious cuts in service to close a budget deficit, in 2004; it met resistance from Carcieri and ended up raising its fares instead. The base, one-way fare went from $1.25 to $1.50. The authority raised the basic fare again, effective Monday, from $1.50 to $1.75.

blandis@projo.com