Starting in August, leaders of the four labor unions contracted to set up shows at the Pennsylvania Convention Center will end a long-standing job protection, and let exhibitors erect and tear down their own booths at the big conferences that fill the blocks-long center and Philadelphia hotels and restaurants

Union leaders say it was their idea. Center managers say it was mutually agreed upon after years of discussion. The new pact is for 10 years.

“At first blush,” you’d think that means “less work hours” for union workers, said Mike Barnes, business manager for the stagehands’ union, IATSE Local 8. But the union has found that “most exhibitors utilized stagehands” even in situations where they were no longer required to in the last contract, which for the first time exempted small booths (under 30 feet x 20 feet) from all-union setup requirements.

The looser rules have translated to more jobs, Barnes and his fellow union leaders say. Convention Center hourly labor data show that union headcount at the center increased every year under the last contract, rising from an average of 100 members every eight-hour day in 2014 to 130 this year — and many more during the busiest weeks of spring and summer.

So the unions now are betting that even looser rules will bring in still more shows. “Any work hours that may be lost as a result of this change will be more than offset by additional bookings,” Barnes said. He said labor joined management in the longer pact, up from five years previously, so they can jointly offer “the best environment to have a convention, for the next decade.”

Center boosters are already telling show organizers that Philadelphia is the most client-friendly of the big-city Northeast and Midwest convention centers, a surprise to anyone who remembers earlier years of labor discord at the facility.

According to Philly boosters, in New York and Washington, exhibitors are restricted from using power tools, hand trucks, or short ladders -- but in Philadelphia, it’s OK.

Chicago and Boston still demand overtime pay after 4:30 p.m.; in Philadelphia, time and a half kicks in only after eight hours, even if the worker starts in the afternoon.

Under the new deal, “our facility will have the most progressive exhibitor rights of any major urban center in the Northeast,” lawyer Gregory J. Fox, the center’s board chair, said in a statement.

Before the 2014 reforms, “we were seeing a lot of lost opportunity, with bookings not meeting the levels we were seeing prior to the center’s 2011 expansion,” said Ed Grose, executive director of the Greater Philadelphia Hotel Association.

After exhibitors gained the right to set up small booths, “we are seeing consistent year-over-year growth,” he said. “By 2021, the number of hotel rooms in Center City will have increased by roughly 30 percent” since the early 2010s.

“We understand that a successful convention center fuels increased demand for the services of our members, while also creating new job opportunities” for hotel, restaurant, and other hospitality workers, said Samuel Staten Jr., business manager for Laborers Local 332, in a statement.

It’s a big switch from the center’s early years, when show managers and exhibitors filled after-show reports with “pages and pages of issues they had with the labor community,” acknowledged John J. Dougherty, business agent for the Building and Construction Trades Council, and for IBEW Local 98, which represents electricians at the center.

By contrast, recent complaints have tended to bypass labor and focus more on how busy (and worn) some city hotels have become with all the traffic, said Dougherty, who is fighting a federal indictment, accusing him of using union members’ funds without approval.

Dougherty said he has started to organize a movement to further expand the Convention Center, whose previous $800 million expansion to Broad Street still ranks as the state’s most expensive public-works project in current dollars. Dougherty says the city will need more hotels to handle the new business, beyond those already on the books.

“This is a big deal,” he said of the new pact.

Dougherty says IBEW members alone worked 20,000 hours — enough to keep 250 members busy every weekday — during a 2½-week period earlier this summer that saw the giant BIO2019, Lightfair International, and other large conventions succeed each other at the center.

He said Lightfair has been back twice in the last five years, since the work rules were first loosened. Members are pleased: “This is a great place to work. You’re cool in the summer and warm in the winter.”

The 2014 contract, signed after years of struggle among the politically connected center board, excluded members of Carpenters and Teamsters union locals, which had resisted concessions. Those locals have not returned to the center. But Dougherty said the Carpenters and other building trades expect to gain jobs building new hotels to pick up new center business, while Teamsters have won more work for center users as bookings increase.

The center has scheduled 19 “citywide” shows — big enough to fill hotels for days — this year, up from 12 in the first year of the contract, said executive director John McNichol.

He demurred on whether the center, managed by West Conshohocken-based SMG, or the city government, which has strong representation on the center board, will soon push for another expansion, which would likely require substantial state aid.

“We do very well in the second and third quarters," but business is still slow in the “darker” months when conventions move to warmer states, McNichol said. “We want to crack into the corporate business of folks who book on a shorter window. If we can attract that business, I can see where having additional space may come into play quickly.”

For now, Dougherty’s “future vision is more optimistic than anybody’s,” McNichol concluded. “But that’s how things get done.”