That kind of stability and predictability will allow the Philadelphia Convention and Visitors Bureau, which markets the center, to help potential customers better estimate their total tab even when they are booking five to seven years ahead.
"This is what no other center in the country can do," Wigglesworth said.
The Metropolitan Regional Council of Carpenters Local 8 and Local 107 of the International Brotherhood of Teamsters have not signed the agreement. Together, they make up half of the Convention Center workforce.
Signing were unions representing riggers, who hoist and assemble heavy exhibits; stagehands, who assemble the stages; electricians; and laborers, who maintain the center, and move props and exhibits around the floor.
The Carpenters have handled most of the assembly work within the center and the Teamsters are responsible for loading and unloading the majority of heavy equipment at the loading dock.
The agreement said that if some unions do not sign the new agreement, their work will be divided among the other unions.
That may result in lower labor costs at the center, because Carpenters are the second highest-paid trade, earning a total of $66.64 an hour in wages, health care, pension and apprentice training.
Some work could go to Local 332 of the Laborers International Union of North America. Laborers earn a total of $46.66 an hour, a third less.
Meanwhile, the Carpenters union wants to "get back to negotiations and get the Convention Center on the right track without any disruption," a spokesman said Wednesday. Teamsters officers did not return calls for comment.
The new customer service agreement replaces the first agreement, signed by all six unions and the Convention Center in 2003. The backdrop was nearly a decade of ugly and sometimes violent jurisdictional disputes at the center.
Intense negotiations, spearheaded by then-Mayor John F. Street, led to the creation of a dispute resolution process and called for post-convention meetings to resolve difficulties and improve future services.
The agreement was basically ignored, with the center's management failing to enforce its provisions, said Patrick Gillespie, head of the Philadelphia Building Trades Council and a former Convention Center board member.
"They just backed away," Gillespie said. "Whatever problems they had. they would let fester and embellish."
The new agreement very much mirrors the old one, but with one key difference.
"SMG will enforce the contract," said Ryan Boyer, who wears two hats.
Boyer is a member of the Convention Center board and a top official of one of the four unions that signed the agreement, Local 332 of the Laborers International Union of North America.
Here's an example: A big sticking point has been how much leeway individual exhibitors should have in setting up their own booths.
In the past, exhibitors were allowed to assemble their booths as long as they were no larger than 300 square feet. No power tools could be used.
Under the new agreement, booth size has been expanded to 600 square feet and modest power tools are allowed.
However, exhibitors can use only their own full-time employees for setup.
That is a key point, because if exhibitors were allowed to hire temporary help, it would create a de facto nonunion workforce.
Under the agreement, it doesn't matter if the exhibitors' employees are unionized. Either way, it's self-limiting, because of the booth size and the necessity of using relatively uncomplicated tools. If the setup is complicated and large, the center's union workforce must do it.
The customer service agreement also mandates the establishment of a regular workforce, improving service.
Each union is allowed to select a group of members who are trained in hospitality and who have passed drug tests. Those workers and their foremen get first rights on the jobs at the Convention Center and can be requested by name. The unions can dispatch other workers as needed.