Mass transit systems nationwide are considering cutting service, laying off staff, raising fares and delaying capital spending to meet rising diesel fuel prices. The spike at the pumps could cost public transportation systems as much as $7.5 billion more this year.

While most public transit authorities are not raising fares yet, they have explored ways to cut costs and save money. Some have eliminated routes or run them less often, ended overtime, reduced travel expenses and cut other parts of their budgets, said William W. Millar, president of the American Public Transportation Association.

If prices remain high, the Capital District Transit Authority, based here, will spend about $900,000 more than anticipated for fuel by the end of its fiscal year, officials said.

The Denver Regional Transportation Authority is considering a 25-cent fare increase on local routes. And in Salt Lake City, the Utah Transit Authority is proposing a 25-cent-per-ride fuel surcharge.

"Fuel prices have more than doubled, and we're anticipating a $6 million shortfall in the 2006 budget year," UTA spokesman Justin Jones said.

The Utah authority is spending $2.65 a gallon for diesel fuel -- $1.44 more per gallon than it had expected to spend. The surcharge, to be voted on by the authority's board, will help make up $2 million of the shortfall.

"Going back to 1970, we usually budget around 91 cents a gallon," Jones said. "We added an extra 30 cents per gallon, but even then it simply wasn't enough. We didn't anticipate the prices would be this high."

It is a familiar story around the country. Denver RTA spokesman Scott Reed said his authority in 2004 spent an average of $1.11 per gallon. It was paying $2.44 a gallon recently. That will leave the Denver RTA about $11 million over budget for the year.

Charles Seaton, a spokesman for the New York City Transit Authority, said that over the summer the authority was paying about $1.81 per gallon of ultra low-sulfur diesel fuel. Now it is paying about $2.44. The authority, with 4,600 buses, burns 900,000 gallons a week.

Public transportation authorities pay less per gallon than motorists because they are exempt from taxes. But transit systems cannot change routes and fares on a dime. Instead, the public and local governments have to weigh in on any decision.

Authorities also fear raising fares will drive away business. Transit authorities around the country have reported increased ridership with the record gas prices.

Brian Shaughnessy, a spokesman for the New York Public Transit Association, said some transportation authorities earlier this year thought the high prices would fall and waited to sign fuel-buying contracts. Instead, they were forced to pay even higher prices.

Near Los Angeles, Foothill Transit says it is sending its buses that run on compressed natural gas on its longer routes. The authority has 192 such vehicles in its 306-bus fleet.

Foothill pays about $1.50 for the gasoline equivalent in natural gas, saving as much as $1.50 a gallon in the Southern California market, executive director Doran Barnes said. But even estimating fuel costs of $1.90, Barnes said his authority will bust its budget.

"We're looking at other ways to try to trim costs," he said. "We may have to cut some support activities or reprogram some capital projects."

A spokeswoman for the Albany authority, Margo Janack, said the CDTA originally planned to spend about $1.50 a gallon but paid $2.10 last month.

In Buffalo, the Niagara Frontier Transportation Authority estimates it has saved $242,000 by buying about 80 percent of its diesel fuel under contract for an average of $1.62 a gallon, spokesman Douglas Hartmayer said.

A bus is fueled in Albany, N.Y., where the city transit agency could spend $900,000 more than anticipated this year.