While investigators try to determine the cause of a fatal Chicago scaffold collapse, building officials are reviewing regulations to determine if additional safety guidelines are needed to protect workers and the public.

The March 2 incident at the 100-story John Hancock Center occurred when winds exceeded 50 mph and no work was under way. But after breaking loose from the tower, a portion of a suspended aluminum platform fell some 42 stories to the street. It crushed three cars, killing three occupants and injuring several others (ENR 3/18 p. 7). A section of the staging remained dangling from the adjacent face of the building. Windows were smashed in the incident.

The U.S. Occupational Safety and Health Administration is investigating, but "it will be some time" before the agency can identify a cause, says Gary J. Anderson, OSHA's area director in Calumet City, Ill.

City officials maintain that Denver-based AMS Architectural Technologies Inc., which was hired to clean the facade and caulk windows, should have moored the scaffold to the roofline or lowered it to the ground prior to the onset of high winds. "They failed to use proper safeguards" called for in city building codes and manufacturer's specifications, says Mary Richardson-Lowry, commissioner for the city's Dept. of Buildings.

AMS suspects the scaffold design was at fault, not the operation, says Ray Hanania, a company spokesman. "We did everything we were supposed to," he says.

Chicago does not require permits for scaffolds, but city code requires scaffolding "be so constructed as to ensure the safety of persons working on or passing under or passing by the scaffold." The city's legal department is reviewing whether to require scaffolding permits, says a Dept. of Buildings spokeswoman.

Most major U.S. cities do not require permitting for scaffolds because it is temporary and often specialized equipment, says William T. Ayers, past president of the Woodland Hills, Calif.-based Scaffold Industry Association Inc., and a member of an American National Standards Institute committee on scaffolds. He says the ANSI code adopted by OSHA and other agencies addresses scaffolding safetybut "is silent" on protection measures for storms and earthquakes. He predicts "tremendous fallout" from the incident and possible code changes.

New York City requires permits for any scaffolding with outriggers, such as the type in use at the Hancock building, says Ilyse Fink, spokeswoman for the city's Dept. of Buildings.

Two of the victims' families have filed suit against the building's owner, Shorenstein Co., San Francisco; Beeche Systems Corp., Scotia, N.Y., which owns the scaffold; Prime Staging Inc., Bensenville, Ill., which assembled it; and AMS. "Somebody, somewhere along the line, dropped the ball," says Thomas A. Demetrio, a local lawyer representing the families.