Gov. Gerald L. Baliles' commission on transportation recommended today the largest tax increase package in Virginia history, including rises in the sales and gasoline taxes to finance an added $571.5 million a year in highway and other transportation projects.

The 30-member commission, which included five former governors, endorsed a plan that would raise the state's general sales tax from 4 percent to 4.75 percent, add 4 cents a gallon in gasoline taxes, and double the sales tax, or so-called titling tax, on new vehicles.

It called for two widely expected actions: building more toll roads and abandoning the state's pay-as-you-go financing for roads by issuing state bonds for highway construction. The bonds, supported by Baliles but long resisted by the state's once-dominant conservatives, would be backed by pledges of sales tax revenues.

The report calls for giving public transportation systems in the state, such as Metro, their first dedicated source of state revenues by pledging 15 percent of all new transportation money for mass transit, airports and seaports.

It urged that localities be given increased taxing powers for transportation needs.

Baliles immediately said he supports the package and will send it to a special session of the legislature that is to convene in Richmond Sept. 15. Because many legislative leaders are on the commission, its major recommendations generally are expected to win approval.

The commission's plan calls for spending $11.8 billion in state and federal funds in the next 10 years on transportation projects in the state, or about $1 billion a year, double the current rate.

The commission suggested that the legislature may want to increase the sales tax from 4 percent to 5 percent rather than 4.75 percent, with the extra funds available for nonhighway uses. That idea may make the spending plan more palatable to local officials and special-interest groups.

Baliles said the plan by his Commission on Transportation Into the 21st Century offers "a framework for the future" that, if enacted, "will open the door to Virginia prosperity" into the next century.

The plan is likely to be well received by the General Assembly because House Speaker A.L. Philpott (D-Henry) and Senate Majority Leader Hunter B. Andrews (D-Hampton), as chairmen of two of the commission's four subcommittees, played key roles in designing the proposal.

No one, including Baliles, who won election last year campaigning on a pledge to improve the state's roads, said today that the plan is expected to be rubber-stamped in its entirety by the legislators. The proposal listed but did not give any specific priority to road projects that it said were critically needed, including a number in Northern Virginia -- presumably leaving that task to a new state transportation board.

Among the major projects that have been proposed in the Washington suburbs:

Widening the Dulles Toll Road to three lanes and possibly extending it into Loudoun County.

Widening Sully Road (Va. Rte. 28), the two-lane road that skirts Dulles International Airport in western Fairfax and Loudoun counties.

Completing the Springfield bypass, a major cross-county highway in Fairfax.

Constructing a Washington bypass, often called the Outer Beltway, in a half-moon route between Fredericksburg, Va., and the Frederick, Md., area. This was listed as a long-range project.

One study released today said the construction industry could handle $1 billion a year in projects only if the work were spread among contractors across the state.

If the Virginia sales tax, now the lowest in the Washington area at 4 percent, is raised to 5 percent, it would match Maryland's rate but still would be below the District of Columbia's rates of 6 percent on most sales and 8 percent on restaurant food.

Boosting the gasoline tax 4 cents a gallon, to 19 cents, would make Virginia's rate among the highest in the nation. Nebraska has a 20-cent rate, and a Virginia commission staff member said one western state recently voted to raise its rate above 20 cents.

The 19-cent gasoline tax rate would be the highest in the Washington region: Maryland charges 13.5 cents a gallon, the District 15.5 cents. Gasoline tax rates in other states contiguous to Virginia range from 15.35 cents a gallon in West Virginia to 17 cents in Tennessee.

"The question is whether our constituents want to pay for all these projects," said Del. Raymond R. (Andy) Guest Jr. (R-Front Royal), the House minority leader. "It's a very ambitious program, to bring us up to date," he said.

Guest was not a member of the commission, which was top-heavy with Democrats, but he said he did not view the plan as a partisan one.

Several commission members, notably former governor A. Linwood Holton of McLean, a Republican, said they thought that the proposal did not go far enough.

In a subcommittee meeting that preceded the commission session, Holton proposed an amendment, defeated 16 to 2, that would have nearly doubled the amount of new revenue.

The cornerstone of Holton's plan called for increasing the state's individual and corporate income taxes by 1 percent. Along with a 3-cent-a-gallon increase in the gasoline tax and various other fee increases, the Holton plan would have generated $1.012 billion a year, compared with $571.5 million in the adopted plan.

He predicted that the adopted plan will not come "anywhere near" raising $1 billion a year because it places too much reliance on the state getting nearly $300 million a year in federal highway money.

He said Gramm-Rudman-Hollings reductions and other federal budget cuts make continued federal aid "a very doubtful item."

Holton also questioned increasing the sales tax because "it is so patently regressive, hitting the little people the hardest."

"Holton was dead right, we're shooting too low" in total revenue, said Sen. Charles L. Waddell (D-Loudoun), a commission member and chairman of the Senate Finance Committee. "But it's a beginning," said Waddell, who voted with the majority.

Former governor Mills E. Godwin of Suffolk, a conservative, called the proposal "a heavy burden -- I would have preferred a more modest approach." He added that he was uncomfortable using the sales tax for transportation.

Godwin recalled that it was during his first administration in 1966 that the Virginia sales tax was first enacted, with most of the proceeds designated for education. "Some wanted more then," Godwin said, but it was held to 2 percent at the start, with a built-in step to 3 percent in two years along with an extra 1 percent for local governments.

Under the proposal, all of the transportation money would be administered by a reorganized Virginia Transportation Board, which, in addition to road building, would coordinate the management and distribution of funds to airports, seaports and mass transit.

The board would include the present highway commission and add three new members, to represent the interests of airports, seaports and railroads.

State Transportation Secretary Vivian E. Watts, urging the commission to forsake a "roller coaster" pattern of highway funding -- up one year, down the next -- said traffic on Virginia's highways increased 44 percent from 1975 to 1985.