Work resumed Friday at the construction site of the Regional Performing Arts Center in Philadelphia as OSHA investigators searched for a cause of last week's accident that injured eight workers.
A spokeswoman for OSHA, Leni Uddyback, said two structural engineers are examining the site where a ramp for an underground parking garage collapsed Thursday, dropping eight men approximately 40 feet into 40 tons of wet concrete.
Dominick Salvatore, Philadelphia's OSHA enforcement officer, said the agency's investigation will focus on two points: the procedure used by workers who were pouring the concrete, and the design specifications for the support scaffolding.
"By statute we have six months to complete our investigation," said Uddyback.
The ramp section of construction was blocked off Friday.
City Managing Director Joseph Martz said that Licenses & Inspections officials were working with OSHA.
"There is nothing to report so far," said Martz. "We're just supplying them with whatever they need."
The concrete was poured to build a 30 -foot ramp from the street to what will be an underground garage for the center, which will house the Philadelphia Orchestra.
Five of the workers remained hospitalized as of Saturday, in stable condition.