But in the intervening 21 months, said Chaput, "I've become really confident we can manage" large crowds, including a visit from Pope Francis, who succeeded Benedict a year ago this month.
Such a visit, traditionally made at the close of the triennial World Meetings, can draw a crowd of a million or more people when a pope says Mass.
But Pope Francis still has not confirmed that he is coming, said Chaput, who does not expect the pontiff to make an announcement more than six months in advance of the next World Meeting. The five-day gathering is set for the last full week of September, 2015.
On Wednesday, Chaput, along with Mayor Nutter, Gov. Corbett and other civic leaders are scheduled to hold a private morning audience with Francis at his residence to discuss the World Meeting and encourage him to visit Philadelphia. But Chaput said he did not know how long the much-anticipated papal audience might last - or even if it might be nothing more than just greeting him in a hallway.
"He's very, very busy. He's got President Obama coming the next day," said Chaput. "So, anything can happen. I'm telling everybody to hope for the best but prepare to be disappointed."
No one in the Pennsylvania delegation would likely be more disappointed than Corbett, who said Monday he was assuming the audience would last about 45 minutes - time enough for him and Nutter and Chaput to tell Pope Francis how much they would welcome his presence, and to paint a picture of things he might see in Philadelphia.
"I was thinking: 'What about a visit to see the work of Sister Mary Scullion,' " a religious sister whose celebrated nonprofit, Project Home, has built housing and provided shelter to hundreds of Philadelphia's poorest. "What he's trying to teach in his ministry is exactly what she's doing," Corbett said.
He said Bishop John McIntyre, an auxiliary bishop of the archdiocese, had also raised the possibility of inviting Francis to visit some of the Catholic-run soup kitchens in the city.
State economic development officials estimate the World Meeting could bring as much as $100 million in tourism to the city and southeast Pennsylvania, yet Corbett said he did not expect the state would help underwrite the archdiocese's costs.
"Once we know if he [Francis] is coming," Corbett said in an interview, "we can determine what we might do." One possibility, he said, is to budget for state police overtime pay in that event. Although the state does offer financial incentives to companies considering relocating in Pennsylvania, he said, these are usually in the form of loans or tax credits, not gifts of money.
Chaput said he expected the World Meeting will cost the archdiocese at least $15 million. That number, he said, is based on the 12 million euros it cost the Archdiocese of Milan in 2012. "And it's my understanding that a lot of the security and safety were provided" by government at no cost to the local church. He said the archdiocese was relying on the generosity of business and philanthropies to fund the gathering.
He noted that Francis' presence would not radically increase the cost, because the federal government would declare his presence a head-of-state visit and take major responsibility for his protection.
Deputy Mayor Everett Gillison, who is public safety director for Philadelphia, said he, too, anticipates the pope's presence would be declared a "homeland security event." If so, he said, federal agencies would take charge of security measures.
Nevertheless, he said, he and his advisers have already begun to consider the logistics of crowd control, medical services, security and such essentials as where best to site a papal Mass.
When Pope John Paul II visited the city in October, 1979, an estimated one million came to see him celebrate Mass at a specially created altar atop Logan Circle, with crowds flowing all the way to the Philadelphia Museum of Art 1,500 yards away.
"But is that the place we would choose now?" Gillison asked, and shrugged. He said he was intrigued to learn that when Pope Benedict said Mass in Milan at the 2012 World Meeting, it was staged at the city's airport.
"Now, I'm not saying I want to close down Philadelphia International," he said. "But these are the kinds of things - line-of-site issues - we're already thinking about."
He said he did not envision the kinds of crowd-control measures used at for New Year's Eve at New York's Times Square, "where they do a lockdown that keeps people behind barricades for 12 hours. Philadelphia is a city founded on principles of freedom."
But Gillison said he also had been studying how cities such as New York and Boston have handled security for papal visits since the World Trade Center attacks of 2001. "So I'm asking things like: 'How did people get there? Did they walk? Take buses? And where were the exclusionary zones that barred people from getting closer?'
"We'll figure it out," he said. "We do big events in this city."
@doreillyinq on Twitter.