SAN FRANCISCO (CBS SF) – More than nine months after the discovery of cracked steel beams led to its closure, the Transbay Transit Center in Downtown San Francisco partially reopened early Monday morning, but without bus service.

The transit center’s 5.4 acre rooftop park at the foot of the Salesforce Tower reopened to visitors around 6 a.m. According to officials, programs and activities will also resume at the park, including live music, yoga and activities for kids.

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Meanwhile, bus service is not expected to resume at the new terminal until later this summer.

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Last September, the $2.2 billion transit center was temporarily closed as a precaution, after two fissures were found in two beams on the third level bus deck at Fremont Street.

Since then, the Transbay Joint Powers Authority (TJPA) said it determined the cause of the fissures and repaired and reinforced the area. The quality of the steel used and the cracks that formed in the steel while the beams were being built are reportedly what led to the fissures.

Once the beams were fixed, this whole facility went through an entire fire and life safety inspection program with the state’s oversight, to ensure that this was safe for people to be around again.

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It was nearly 20 years ago, on November 2, 1999, that voters approved funding for the new terminal. Construction did not begin until September 2013. The transit center opened in August of last year before discovery of the first cracked beam prompted the shutdown the following month.