(CBS SF) — BART trains are back in service between Oakland and San Francisco after the Transbay Tube was shut down for the weekend.

Crews had to replace a section of of crossover tracks, which officials say will help reduce noise from trains.

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Transbay service is scheduled to be closed again over Labor Day weekend.

The transit agency says the shutdowns may be inconvenient, but the maintenance will benefit passengers in the long run.

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“What we’re doing is rebuilding a mechanism,” said BART spokesperson Taylor Huckaby. “[It] helps us mitigate delays, gives us optimal flexibility.”

BART board member Joel Keller told KPIX 5 Sunday morning there’s also talk of eventually building a second Transbay Tube.

“A number of officials have stated their support for it,” Keller said. “It’s going to be a huge undertaking, a lot of money a lot of planning, a lot of timing, so we have to start looking at that as an option.”

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Before that can happen, BART needs about $9 billion to maintain the current system. A bond measure to fund part of that could be on the ballot next year.