Months more of tunnel repairs

State officials acknowledged yesterday that repairs on the Interstate 90 connector tunnel will take several months and unveiled what they called a comprehensive plan to handle post-Labor Day traffic.

The plan includes delaying daytime roadwork and adding 10 trips on commuter rail lines and more runs on the MBTA subway. Additional T personnel are expected at most stations next week starting Tuesday, and as needed after that, to direct passengers unfamiliar with the subways. Officials urged motorists to use public transit, carpool, or change their work hours to avoid rush hour.

Drivers ``need to plan ahead and think about changing their normal driving habits come Tuesday morning," Transportation Secretary John Cogliano said yesterday.

Daniel A. Grabauskas , general manager of the Massachusetts Bay Transportation Authority, said Cogliano called for ``all hands on deck" at a meeting Tuesday of transportation officials to discuss the plan.

``The secretary's request was to boost service where we saw an increase in ridership. . . and make it as easy as possible for folks to get in and out of the city on public transportation," he said.

The MBTA also plans to add extra rush-hour service on the commuter boat from Quincy to Logan International Airport. The South Shore ferry has been a popular alternative to driving after the tunnel closings, quadrupling ridership on some days in July.

Besides delaying road maintenance during the tunnel repairs, the state sped up a number of other road projects, including paving on the Tobin Bridge, over the last two weeks to ensure they were complete by Labor Day.

Boston traffic after Labor Day is projected to increase by 15 to 25 percent, according to some traffic consultants, because of the return of thousands of college students and families after summer vacations.

Cogliano and Governor Mitt Romney had hoped to have portions of the tunnels open by Labor Day, though they have never committed to a specific date. Yesterday's announcement that the repairs will take several months is the longest timetable state officials have used.

``We're not ruling out other remedial actions we may have to take," said Jon Carlisle , spokesman for the Executive Office of Transportation. ``I'm hesitant to put us in a position where we say the project will be completed by a certain date."

The discovery earlier this month that 3,300 ceiling brackets in the I-90 connector and ramps need to be replaced -- and each redesign and repair needing federal approval -- has slowed the repair process and delayed the reopening, officials said. Carlisle said none of those brackets have been replaced because the state is awaiting federal approval, which could come by the end of the week.

Asked if it could take a year before the tunnels are opened, Cogliano replied, ``As the governor mentioned publicly already, it's going to take months."

State officials hope the warnings to commuters work as well as alerts during the 2004 Democratic National Convention in Boston. Dire predictions about the nighttime closing of I-93 through Boston caused many workers to take the week off, and there were no traffic jams.

However, those road closings were limited to nights, lasted only four days, and occurred in July, when traffic is lighter.

The combination of post-Labor Day traffic and major tunnel closures is ``fairly unique," Carlisle said. ``It's a little difficult to predict what impact this will be," he said.

Seven-and-a-half weeks after the ceiling collapse that killed Milena Del Valle of Jamaica Plain, both east- and westbound tubes of the Ted Williams Tunnel have partially reopened. But the connector tunnel, which links the Massachusetts Turnpike and the Ted Williams Tunnel, remains closed with no reopening scheduled. As a result, Logan-bound traffic from the turnpike is being detoured north on I-93 to the Callahan Tunnel. Traffic leaving Logan via the Ted Williams Tunnel cannot get directly to the turnpike or I-93, but must detour through South Boston.

Although the opening of an eastbound ramp leading from South Boston to Logan helped siphon off some traffic from downtown Boston, many drivers are using pre-Big Dig routes, including detours on surface streets downtown and in South Boston.

Carlisle said engineers and state officials are trying to reopen Ramp D, which leads from the westbound Ted Williams Tunnel to Interstate 93. State studies show that the opening of that ramp, combined with reopening the eastbound ramp, could cut traffic congestion around the Big Dig by 40 percent.

Cogliano said much of the last seven weeks has been spent analyzing the tunnels -- section by section, each measuring 24 feet wide by 40 feet long -- for defects and redesign. ``These tunnels . . . it took approximately two years to design these, and we're reviewing and redesigning these things in a matter of weeks," Cogliano said. ``So it does take some time."

The 3,300 steel brackets that need to be replaced support concrete ceiling panels in I-90 connector tunnels and ramps. The bracket work is in addition to repairs and replacements of the epoxy-and-bolt system that apparently failed in the ceiling collapse that killed Del Valle .

The Massachusetts Turnpike Authority board of directors agreed yesterday to spend as much as $15 million on the growing list of safety repairs in the Ted Williams and I-90 connector tunnels. Big Dig project director Michael P. Lewis said the $15 million figure is ``purely an estimate" and the cost could rise if more problems are discovered.

Mac Daniel can be reached at mdaniel@globe.com.