PROVIDENCE — The state Turnpike and Bridge Authority needs to raise tolls to pay for $50 million worth of repairs to the Pell and Mount Hope Bridges, Chairman David Darlington told a legislative committee Thursday.

Darlington asked the House Finance Committee to approve borrowing the $50 million through a bond issue for the work, which would include repairing rusted steel and doing painting on both bridges. He said that a toll increase would be needed to cover the bond issue, but that the authority wants to avoid raising tolls for Rhode Island residents.

Darlington said it would be the first toll hike in the history of the Pell Bridge, which opened in 1969. And if tolls are reinstituted on the Mount Hope Bridge, it would be for the first time since they were eliminated in 1998. Maintenance on the Mount Hope Bridge is now paid for with tolls paid by drivers crossing the Pell Bridge.

Darlington said that an ongoing traffic and revenue study would produce the detailed information that would provide the basis for a toll proposal. But he guessed that tolls on the Pell Bridge for out-of-state cars using EZPass transponders might rise to $3.50 to $4 from the present $1.75.

Rhode Island residents would continue to pay 83 cents to cross the bridge, he said. That discount was challenged in federal court in March by a Connecticut woman. A similar lawsuit has been filed by a Rhode Islander against Massachusetts authorities challenging toll rates favoring residents there.

According to the legislation before the committee, the bond issue could actually cost as much as $132 million when the cost of 8-percent interest is added in, assuming a 30-year maturity for the bonds.

A TBA staff letter said the repairs would include $42-million worth of painting and repairs to the steel of the Pell Bridge, and another $6 million for similar work on the northern approach of the Mount Hope Bridge. The bond issue would also cover $2-million worth of security upgrades for both bridges, including cameras, sensors, alarms and lighting.

The work would be done during the next two years.

“There is some steel that needs immediate attention,” Darlington said. He said the authority has already installed some extra bracing under the Mount Hope Bridge.

He said he would have preferred to have the study in hand before asking the General Assembly for permission to borrow the money. But he said it won’t be done until this summer, which would put off legislative consideration until next year.

“We’re uncomfortable letting the repairs go that long,” he said. Given the go-ahead, he said, “We’d start constructing the scaffolding this fall.”

Darlington said the need for repairs doesn’t mean either bridge is unsafe. “There’s no risk to anybody,” he said.

In December 2007, the authority made public a consulting study saying it faces a long-term $200-million-plus deficit because its principal revenue source, tolls, won’t keep up with the cost of maintaining the bridges.

Darlington said the $50 million is the first part of that cost.

blandis@projo.com