The rainbow-adorned portal into and out of Marin will soon bear a new name: the Robin Williams Tunnel.

The state Senate on Thursday approved the resolution introduced by Assemblyman Marc Levine, D-San Rafael, to change the name of the Waldo Tunnel. The state Assembly took the same action in April. Because it is a resolution, the change doesn’t need a signature from Gov. Jerry Brown.

“I’m very happy,” said Julie Wainwright, the Tiburon Peninsula resident who started the Change.org petition to rename the tunnel in honor of Williams. “It really speaks to the power of him.”

Levine has noted that Williams’ career began in San Francisco and that he grew up and lived in Marin, so naming the Highway 101 tunnel after him “connects those two lives,” and that in his role as “Mork” on the TV program “Mork and Mindy,” Williams often wore rainbow-colored suspenders. Painted rainbows adorn the southern portals of the Waldo Tunnel.

It will cost roughly $3,000 to make sign changes, money that would have to come from donations. Wainwright said her consignment company, The Real Real, will underwrite the effort.

“It’s a pretty cut-and-dried process,” said Steve Williams, Caltrans spokesman. “It’s a matter of receiving the money and making the signs.”

The change could happen as soon as the fall, a Levine spokesman said.

Wainwright’s Change.org petition to rename the structure “The Robin Williams Tunnel” has collected almost 62,000 electronic signatures. The request is being made: “To remember and honor the very important citizen and world renowned entertainer, Robin Williams, for the joy he brought to the world and to bring awareness to the silent illness that eventually took his life.”

Williams committed suicide Aug. 11, 2014, at his home in Tiburon. He was 63. Levine said he has been in touch with the Williams family and he said the family approved the idea.

Williams attended Redwood High School and the College of Marin before launching his comedy and acting career in San Francisco.

The tunnel is now named after William Waldo, who was a Whig Party candidate for governor in the mid-19th century.

It was 1970 when the rainbows went up, by order of Alan S. Hart, former director of the San Francisco District of Caltrans, then known as the state Division of Highways. Hart was about to retire and made a last-minute decision to skip permission from his bosses in Sacramento, and he ordered the portal arches to be painted multiple colors because they reminded him of rainbows.

Initially the Sacramento highway officials were furious, but they calmed when the public embraced the rainbows, which somehow fit naturally into the rolling landscape. Marinwood resident Robert Halligan, a Caltrans spokesman and an engineer, took the idea and pushed it through, making sure the job got done.

“Naming the tunnel after Williams really fits,” said Wainwright, who did not know Williams but would see him around town. “The rainbow is fun and whimsical. It’s clear he really loved Marin and San Francisco.”