The much talked about light show on the western span on the Bay Bridge made its debut for a damp but enthusiastic San Francisco crowd Tuesday night.

After weeks of test runs, the 25,000 LED lights were switched on at 9 p.m when Leo Villareal, the artist who created the synchronized display, pushed a key on his laptop computer.

Even rainy weather did not deter thousands of spectators. The crowds decked out in foul weather gear started lining up along the Embarcadero hours before the scheduled start time to make sure they didn't miss the moment the Bay Bridge was transformed into a public work of art.

The light show changes constantly and the sequence is designed to never repeat. The artist said the abstract nature of the installation is designed to keep it open to interpretation.

"My goal is to just create the equivalent of a digital campfire that people can people can be around and enjoy," said Villareal.

Despite the rain that started coming down about a half-hour before the lights went on, the sidewalks were packed with onlookers. All the outdoor seating at restaurants and cafes along the Embarcadero was also full.

"With the temperature we're feeling right now it's unusual to see my patio chock-a-block," said Andrew Upton of Chaya Brasserie.

Restaurants that were not closed for private events were booked out a week in advance, a rare event for a cold and wet weeknight.

"I've never seen this many people down here on a Tuesday night," said McKenzie Bryan of San Francisco.

San Francisco Mayor Ed Lee says the art installation is expected to attract 50 million visitors and $97 million over the next two years.

"You can imagine anything you want in the lights," said Lee. "For me, it's the mustache you'll see every night."

Lee said "The Bay Lights" will serve as "a beacon for our arts community" and will complement other large events on the waterfront, including the America's Cup sailing race starting later this year.

The mayor said he thinks the light sculpture may be so popular that people will want to keep it beyond the two years for which it has permits from state officials.

"People, including myself, will want this to be ongoing," he said.

Ben Davis, chairman of Illuminate the Arts, the group overseeing the project, said even if the lights remain past the current two-year plan, they would likely have to come down when Caltrans does its repainting and scheduled maintenance of the bridge cables in five years.

"It's on a living, working bridge and that bridge needs to be maintained," Davis said. "It's going to have to come down and another solution will have to be found or it will be an ephemeral work like it was designed to be."

Some found the city's projections to be optimistic

"It's what I call a BHAG - a big hairy audacious goal," said San Francisco resident Marichele Detrempe.

But now that the seemingly impossible project has been completed, others said they don't want to doubt the revenue.

The cost of the Bay Lights show is estimated at $8 million, all from private donations.

The project is still seeking about $2 million in funding, which Davis said he was confident will be raised.

"This is an amazing, forward-moving project that has momentum, and the love is just starting to mount for it," he said.

Illuminate the Arts would have to foot the bill for any gap in the funding, he said.

Each diode is for sale online. Bay Lights had already raised $75,000 before the installation went live.

The light sculpture is 1.8 miles long and up to 500 feet high with each bulb siting a foot from the next.

The bridge is to be illuminated from dusk until 2 a.m. every day. The cost of electricity is said to be $11,000 each year.