For the first time in more than 10 months, transit will return this weekend to the Transbay transit center, which was closed after the discovery of cracked support beams. Buses will roll in and out of the terminal starting Sunday with weekday commute service beginning Monday.

Here’s what commuters need to know:

Which buses will run in and out of the Transbay transit center?

AC Transit will run its 27 Transbay bus lines in addition to service on four Early Bird Express buses it is operating for BART. WestCAT Lynx and Muni’s line 25-Treasure Island bus will also use the transit center’s bus deck. Greyhound is expected to make the move in a few weeks. Amtrak, which runs connecting buses from Emeryville, has not yet signed a contract to use the bus deck. Several Muni and Golden Gate Transit buses are already stopping in a plaza just outside the center.

Where do I catch the bus?

The bus deck is located on the third floor of the Transbay transit center. A map showing the boarding area for each bus line can be viewed online at actransit.org.

Commuters who take Transbay buses into San Francisco “won’t need to do anything” except know that they’ll be dropped off inside the transit center, said Robert Lyles, an AC Transit spokesman. For those leaving from San Francisco, the temporary terminal will be at least partially fenced off — with signs posted — to let riders know their buses have moved. AC Transit will have ambassadors on duty to direct passengers.

Why was the transit center closed?

The center opened with much fanfare on Aug. 12, 2018, but it was evacuated and then shut down on Sept. 25, after a worker discovered a crack in a crucial support girder. A second cracked girder was soon discovered.

Is the bus deck safe?

An independent panel of structural engineers and metals experts, as well as engineers for the Transbay Joint Powers Authority, have deemed the transit center, including the bus deck, safe for use. They made their decision after reviewing the damaged girders, approving and inspecting repairs, and examining other parts of the three-block-long center that might be susceptible to cracking. The center and the rooftop park reopened July 1, but bus service was delayed while the deck was cleaned up and drivers were trained.

What’s the advantage of using the bus deck instead of the Temporary Transbay Terminal about a block away?

The big advantage is that the bus ramp off the Bay Bridge makes for a faster ride. It does that by providing direct access to the bus deck, taking buses off sometimes congested city streets. The ramp and bus deck can cut anywhere from five to 20 minutes, and occasionally more, off a trip.

What else is inside the center?

It’s not exactly inside the center, but the 5.4-acre rooftop park is the big draw. The lushly landscaped park has grassy knolls, elaborate gardens, patios and gathering spots. It offers an array of activities from yoga classes and concerts to games, playgrounds and a kids’ reading room.

In the months to come, businesses ranging from restaurants and coffee shops to medical services will open on the second floor of the center. Food trucks operate outside the terminal and carts serve food inside the park.

How will the return of the buses affect the fountains in the rooftop park?

A linear “bus fountain” that lines the northern edge of the rooftop park spurts jets of water into the air whenever a bus rolls across the bus deck below. The fountain has been spraying the skies, and unwitting visitors who get too close, sporadically over the past two weeks as AC Transit has been running training buses. With the resumption of full bus service, showers from the fountain will become far more frequent.

Where can I get more information about the Transbay transit center?

Visit the center’s website at salesforcetransitcenter.com.

Michael Cabanatuan is a San Francisco Chronicle staff writer. Email: mcabanatuan@sfchronicle.com Twitter: @ctuan