Across the country, passenger car drivers pay $6 to cross the Golden Gate and San Francisco-Oakland Bay bridges in one direction during peak hours. But their commuter plans are open only to carpoolers and are far less generous than Maryland's — even with the proposed changes.

In the Mid-Atlantic, the nearly mile-long Delaware Memorial Bridge, a major river crossing on the main interstate route between Baltimore and New York, is facing many of the same maintenance issues as Maryland's toll bridges. The current round-trip toll of $3 is scheduled to go up to $4 on July 1 to pay for infrastructure improvements.

Perhaps the closest match in the country to the Bay Bridge in terms of age and length is Michigan's Mackinac Bridge, which connects the state's mainland with its Upper Peninsula. That five-mile-long bridge, opened in 1957, now collects $7 for a round trip. Unlike the Bay Bridge, however, it is not a major commuter route.

In recent decades, Maryland has seen far less political strife over tolls than many other states. To a degree, that's because of the independence of the authority, whose decisions are not subject to review by the legislature or the governor. But, as Samuel noted, it is probably also because tolls have not increased much.

With the proposed increases, however, polls could become a hot political issue.

In the audience as the board gave its OK to proposed increases was state Sen. E.J. Pipkin, the General Assembly's leading critic of the toll authority. The Eastern Shore Republican said the increases were unnecessary and mocked the contention by board members that they need to educate the public about the reasons for the increases.

"I think the board needs to be educated that a 300 percent toll increase is outrageous … and incredibly out of touch with the struggles of working families today," he said.

In addition to the toll increases and the E-ZPass discount, the board's proposal would make significant changes to the way Maryland administers tolls. Among its provisions, the plan would:

•Scale back Maryland's commuter discounts to levels closer to the national norm. Under the proposal, commuter discounts would be lowered to 70 percent of the cash rate in October and 65 percent in 2013. Thus, a commuter using one of the harbor crossings in both directions would see a daily increase from 80 cents now to $1.80 in October and $2.80 in 2013.

•Eliminate the decal system at the Thomas J. Hatem Memorial Bridge, under which frequent users can pay $10 for unlimited use of that Susquehanna River crossing for a year. The authority would replace the decals with an E-ZPass-based system under which users would pay $36 a year starting Oct. 1 and $72 a year starting in 2013.

•Replace the current $3 fee for mailing notices of tolls due with a 25 percent surcharge on the applicable toll. That surcharge would apply to vehicles that use the ICC without E-ZPasses and get a camera-generated bill in the mail, as well as to users of other toll facilities who go through E-ZPass lanes and whose payments don't register. The effect would be to lower the surcharge on drivers of personal vehicles and increase them for large trucks, which pay higher per-axle tolls.

State Transportation Secretary Beverley K. Swaim-Staley, who chairs the board, said the authority spent $200 million recently on Bay Bridge deck replacement and repainting and $100 million on rebuilding the driving surface of the Hatem Bridge. She said tolls are the only way to pay for such repairs.

Members of the authority board "have a legal and fiduciary responsibility to be able to pay the bills and pay the bonds," she said.