WHEN THE BIG, yellow box truck pulled over on Vine Street yesterday morning near the delivery entrance to the Pennsylvania Convention Center, a group of men in shorts and T-shirts slowly walked toward it, picket signs around their necks.

The weather was just right for the hot and bothered members of Teamsters Local 107 who were protesting being "Locked Out," as their signs said, of work at the convention center after they and Carpenters Local 8 failed to come to an agreement on work-rule changes.

The driver of the truck said he wasn't a union member and didn't want to be identified. After making a few phone calls, he left.

"I can't cross the line," the man said. "It's dangerous for drivers to cross picket lines."

John Dougherty, leader of the electricians Local 98, was less intimidated by the picket line and crossed it, escorting union members into the convention center in the morning along with leaders of Laborers 332 and the Stagehands union. Meanwhile, the Carpenters filed a complaint with National Labor Relations Board, alleging unfair labor practices against the convention center and its management.

Dougherty said a few Teamsters yelled at him when he crossed their picket lines, but he placed blame for their situation on the sidewalk squarely on their leadership, saying the Carpenters refused to sign the agreement while the Teamsters "chose" not to return from a conference in Las Vegas in time to sign.

"The Teamster doesn't know why he's outside," Dougherty said. "They picket once or twice a month. I picket 20 times a day."

The pickets were far outnumbered by the police presence outside the convention center. The protesters declined to comment, referring all calls to their home offices. William Hamilton, leader of the Teamsters Local 107 did not return requests for comment and Marty O'Rourke, a spokesman for Carpenters Local 8, declined to comment.

Pete Peterson, a spokesman for the convention center, said there were no issues stemming from the protest and there has been no talk of further negotiations. He said the driver who left without making his delivery was a Teamster.

"The majority of unions saw the importance of making changes to attract new customers," Peterson said in a statement. "Two unions chose not to accept the new work rules by the deadline. We're moving forward and the four unions who signed the agreement have the skill sets needed to meet our needs."

On Arch Street, Darryl Shirley, 57, a member of Laborers Local 322, said he was torn seeing the protesters outside.

"I feel for them but someone's got to do the work," he said. "You can't stop progress."