"I cannot wait!" Strauss exclaims, as pigeons flutter back to criss-crossing utility lines.
Mike Coalision clambers up a ladder to the roof where the billboard stands, framing an image of a grass-covered car. He goes to work, and within moments the ad for a collision center is gone, replaced by the formidable bespectacled face of South Philly's own Antoinette Conti, looking down at the gaggle of reporters and museum people and, of course, at Strauss, the photographer who created the portrait.
This unforgettable image, with its curves of chin and neck and flowered collar-line, is a key work featured in Strauss's midcareer retrospective at the art museum, which opens Saturday for a run through April 22.
And still the 41-year-old Strauss has her eye glued to her camera. She's never seen this image so big (12 by 25 feet) before, never experienced its total command.
"I've got to keep taking pictures of this guy putting it up because I'm so excited about it," she says to no one in particular.
Coalision finishes his work and waves from the roof.
"She's Antoinette Conti, make no mistake!" affirms Strauss.
For the next two months, the Conti billboard - the formal title of the photograph is La Corona - will peer over the Acme parking lot; she will then be replaced by the image of Fernando Trevino.
Conti is second-generation Italian-American; Trevino is first-generation Mexican-American. Both are South Philadelphians - next-door neighbors, in fact - and their presence atop Lime Organic Cleaners embodies for Strauss the neighborhood's changing nature, its growing ability to accommodate difference, its expanding tolerance.
The images are also part of an unusual feature of the Art Museum show: It is moving way outside the walls of the museum. More than 50 billboards all over town will feature Strauss images. Clear Channel Communications donated 40 billboards, says Gary Turner, a Clear Channel senior account executive, and the museum rented several more.
"It's very exciting," said Turner. "I love the fact that we have art on the boards."
"I proposed it to the art museum," Strauss recalled. "And then it became this massive, massive project. My original idea was three billboards. Then it became seven billboards. And it just kept growing."
On a recent frigid morning, Strauss led a little tour of several board locations. Installation of La Corona was the first stop, a potent image for the artist known for her decade of annual one-day shows of photographs installed in the foreboding, concrete landscape beneath I-95 at Mifflin Street. The I-95 shows ended last year.
Stauss is a warm, diminutive woman who revels in the seemingly familiar world of the street. She captures lives of ordinary people in ordinary circumstances, circumstances that often have a lingering, debilitating bite. Poverty, drug addiction, urban indifference - Strauss shows them all, uncovering an essential humanity.
But her work is also about its surroundings. The I-95 shows transformed an unlikely piece of city real estate. La Corona does the same. The dual portraits of Conti and Trevino reflect and inform the surrounding neighborhood, not always thought of as the most welcoming.
As if to make that point, an African American man comes up to Strauss as she looks at La Corona, introduces himself, and quickly falls into conversation about the change in the neighborhood.
"I wouldn't even walk through here 20 years ago," he tells her. "Now I live here!"
Strauss, who has joked that she is "as gay as it gets," nods her head and touches his arm.
"I know," she says. "I am totally comfortable on my block. Totally comfortable."
Conti isn't along on the tour to discuss her ascension to billboard status, but Charday Laverty certainly is. An image of a thoughtful Laverty, lying on a bed, will soon be up on Torresdale Avenue near Levick Street. Laverty met Strauss a few years ago and worked on a documentary about her.
"It feels a little awkward because I've never been on something like a billboard before," Laverty says. "But it feels pretty cool. I'll never be in this situation again, so it's awesome."
From the Acme parking lot, the tour heads to 15th and Vine Streets, where a billboard diptych displays an image of a sign with words blotted out next to a woman, head thrown back, laughing. Behind the woman are swirls of color - a mural of a flaming oil derrick decorating the Blowout Lounge in Morgan City, La. The photo was taken during the 75th annual Louisiana Shrimp and Petroleum Festival shortly after the BP oil spill disaster in the Gulf in 2010.
At Girard Avenue and 15th Street, Strauss and her entourage stop for a look at another diptych: Black Friday balloons - Mylar sale balloons floating in the Wal-Mart in South Philadelphia - and a half-finished cake from the Shrimp and Petroleum Festival.
On Market Street, west of 30th Street Station, the images are quiet and poignant: one depicts the decaying back walls of houses built on Osage Avenue following the 1985 MOVE bombing, the other shows a simple sign in Grand Isle, La., shot following the oil disaster: "Don't forget us," it reads.
The two images, a continent and decades apart, seem intimately connected.
"The MOVE bombing was a very important and a very painful part of our city's history that I feel strongly should be discussed, both in the community and in the city government," says Strauss.
Never forget the capacity of people to forget - it's something Strauss tackles, and seeks to counter, every day.
Contact culture writer Stephan Salisbury at 215-854-5594, firstname.lastname@example.org, or @SPSalisbury on Twitter.