Starting this summer, buying a ticket to a Golden State Warriors home game, a concert or any other event at Chase Center in Mission Bay will come with an extra perk: a free pass to ride Muni for the day.

The Warriors are paying for the free rides as part of a concerted push to ease the crush of traffic expected to accompany Chase Center’s opening in September. The team and the San Francisco Municipal Transportation Agency are encouraging people to take public transportation to the 18,000-seat arena rather than drive.

“We want people to take public transit to Chase Center, so we’re making it as cheap and easy to do so,” Mayor London Breed said in a statement. “This program allows Warriors fans and concert-goers to get to the front doors of Chase Center at no extra charge.”

Event-goers can present either a paper ticket or an electronic one as proof of payment for their Muni ride on the day of their concert or basketball game. Muni attendants will also be trained to let Chase Center ticket-holders through turnstiles at train stations.

“I’m very pro-public transit and glad they are getting people to get used to getting to the arena that way,” said Andie Cockerill, a San Francisco resident who has tickets to the Eric Clapton concert at Chase Center on Sept. 11.

“Transit is the most reliable, hassle-free way to get to the game,” Tom Maguire, SFMTA’s acting director of transportation, said in an email. “The city has partnered with the Golden State Warriors to ensure that event patrons can get to and from Chase Center safely, efficiently, sustainably and with the minimal possible impact on Mission Bay residents, merchants and other employers in the area.”

Breed convened a working group of more than a dozen city departments in February to help ensure city infrastructure and operations will be ready to handle the influx of thousands of people descending on Mission Bay for Chase Center events.

The neighborhood is already struggling with congestion due in part to an influx of development there.

The SFMTA and other city agencies have taken steps to boost transit ridership ahead of Chase Center’s public debut Sept. 6, when Metallica and the San Francisco Symphony will christen the arena’s stage.

The agency is nearing completion on a project to widen the boarding platform for the Muni T line on Third Street between South and 16th streets near the arena. The platform, designed to hold 700 people, will enable four two-car trains to load at the same time on each side.

The city will also run more T trains and plans to add express bus routes along Van Ness Avenue and from the 16th Street BART Station before and after events. A temporary ferry service is also expected to shuttle event-goers to and from the East Bay and Marin.

Officials expect new parking rules and street restrictions during events — such as designated pickup and drop-off zones for ride-hailing services — will help smooth transportation to the arena. The Warriors have also paid to hire 26 parking control officers to manage traffic during events. Just how much the Warriors will pay for the free Muni ride program will depend on the number of extra Muni riders on event days.

“One of the best things about Chase Center is how easy it will be to get to by train, by bus, by ferry, by bicycle and by walking,” said Warriors President and Chief Operating Officer Rick Welts.

Dominic Fracassa is a San Francisco Chronicle staff writer. Email: dfracassa@sfchronicle.com Twitter: @dominicfracassa