Emily Cashman walked out of the Franklin Institute on Saturday afternoon and from the top of the steps "I-spied" the podlike green buggy across the street, turned to her father, Bill, and said, "Let's do that!"

They had no schedule to keep. It was one of those sweet and weightless cotton candy days for a 5-year-old girl and her father, who live in the Northeast, to go downtown and enjoy the city. So her father said, "Why not?"

Even though he didn't know exactly what he was agreeing to do.

"I thought it was a motorcycle," Emily said. On closer inspection, they could see it was something else. Something new. A recumbent tricycle connected to a two-person bench and a sleek canopy.

After years of planning and waiting for legislative permission, Philadelphia's pedicabs finally hit the streets Saturday.

"Here's the green job sector of Philadelphia," said Sean Leahy, 22, freshly graduated from Temple University with a bachelor's degree in environmental science. He was the first of four drivers who took passengers for their maiden voyages on the canopied Velo-Park pedicabs. He plans to do the work full time until September, when this summer's test season ends.

On his daily bike ride around the city, Mel Seligsohn saw the pedicabs and stopped to find out more about them. Specifically, were jobs available for someone like him?

"I know this city like nobody's business," said Seligsohn, a superbly fit 71. The retired businessman, who lives on Logan Square, said he thought the pedicabs were brilliant.

"I'm stunned. It's so unusual. I hope Philadelphia can support this," he said. "They look great, and if I were a tourist, I'd do it."

Another company, Chariots of Philly, has a fleet of 10 open-air pedicabs. (There is a third independent operator with one.) "We're competitors, but we share the same goals," said Tom Dambman, co-owner of Chariots.

Rob Stuart of the Philly Bikecab Alliance, who helped negotiate the necessary compromises with the Streets Department and cabdrivers, agreed that there was plenty of room for everyone.

"It's not just transportation. It's an experience," Stuart said. "I think we'll show that bike cabs and cabs and people can get along just fine."

Unlike in New York, where pedicabs started out strong but then "went to excess" with no limits or regulations until the industry had to be reined in last year, Stuart said.

Philadelphia has taken a more prudent approach.

"It's a limited trial here. We'll be monitored by the Streets Department to see if there's any congestion," Stuart said.

He said he was sure the experiment would succeed. "People will start to ask, 'If it makes sense on the Parkway, why don't we have it in Old City?' "

Dambman and his brother tried to introduce pedicabs to Center City once before. "From 2003 to 2006, we operated in Manayunk, then expanded to Avalon while we waited for City Council to pass legislation."

In November, Council unanimously passed that bill, sponsored by Councilwoman Blondell Reynolds Brown. It allows pedicabs to operate, but restricts the streets they can use and requires drivers to be licensed and taught some city history.

"Let's go to the train station," said Cashman, climbing into the passenger bench of the pedicab alongside Emily. They could easily have walked, but they figured it would be worth the $1-a-block fee.

"It feels like a roller coaster!" Emily said.

Leahy, the driver, gasped, mocking a severe wound to his ego. "A roller coaster. I haven't even moved yet!"

"I think she means the seat belt," Cashman said soothingly.

"Ready?" Leahy said, then backed the pedicab out of its parking spot and pedaled triumphantly away.