The future of Pittsburgh was the subject at the Northwest Bank Developers Forum, held Monday morning in a packed room at the Union Trust Building — itself a symbol of Pittsburgh’s illustrious past, painstakingly restored and refitted for the types of high-tech firms that are driving Pittsburgh’s new economy.

Mayor Bill Peduto, County Executive Rich Fitzgerald and a host of active Pittsburgh developers discussed the challenges of managing future growth, rather than the decline that has defined Pittsburgh for so long.

“We’re ending last year with $1.3 billion in development,” said Peduto, adding that this year could see up to $2 billion in development.

“But there are areas of the city that are completely cold and haven’t seen any development since the 1950s,” he noted. “We don’t want to see overgrowth occur that will drive businesses or people out.”

One particular subject kept coming up again and again: transportation.

“For the next 50 years, we have to figure out how to bring people into the city to work,” said Peduto. “We have to not simply be wedded to what the past was…What I’d like to see over the next five years is to turn the Pittsburgh Parking Authority into the Pittsburgh Mobility Authority.”

That means marinas for boats along the river, “a gondola system” and driverless vehicles running on electricity. “And yes, it’s about bikes, because that’s how a lot of people get around,” said Peduto. (Note: The gondola refers to an airborne system like you would see in a ski resort, not the one in Venice, Italy.)

Downtown itself is going to see a shift in the kinds of retail it can support.

“We have a really strong food and beverage base,” said John Jackson, of Cushman & Wakefield Grant Street Associates. “I think it’s (about) more residents moving Downtown. That will open the door to more retailers.”

Big retailers like Target like to see a Downtown residential population in the 30,000-person range, like in Boston. Pittsburgh isn’t quite there yet, but Jackson makes the case that the 140,000 people who work Downtown and in its environs are a point in Downtown Pittsburgh’s favor.

“From a retail perspective, we need to restore balance to the system,” noted Jackson. “Some general merchandisers, some entertainment. I love all the restaurants, but we need something complementary.”

The other issue that looms large over the city is air quality, and how re-industrialization — via the Shell cracker plant in Beaver County, and its potential downstream spin-offs — will affect the air.

“I don’t want to see us kill the golden goose — technology, medicine,” said Peduto. “I don’t want to see one industry jeopardize that in any way.”

Peduto also said that when he stated that he wouldn’t support building any more cracker plants, it was in response to reports that as many as seven could be planned for the Ohio Valley.

“We have to have this conversation,” said Peduto. “The past Pittsburgh and the next Pittsburgh are in conflict when it comes to this issue. I’m told on a weekly basis, clean your air and clean your water.”

“Over the last decade, we’ve removed 88 percent of particulate matter from the air,” said Fitzgerald. “We’ve seen improvements, but there’s a ways to go … For those who are just moving here, it’s like, ‘Why hasn’t been this been done more quickly?’”

As Pittsburgh grows and builds, there are opportunities to do it right.

“You have Phipps, a ‘living building,’ that uses no more energy than a flower,” said Peduto. “Just about every single thing in that building was built in a 100-mile radius.”

The next generation of building, he notes, needs to be looking at Western Pennsylvania.