Bob; Hundreds of construction workers on a project of this size is not unusual. Here is a quote from one report;

"(NJ Governor)McGreevey confirmed that 30 people were trapped in the initial collapse at 10:30 a.m. ET. Construction workers and first-response workers pulled 21 people from the wreckage themselves before other rescuers arrived.

Nonrescue personnel have been moved back two blocks from the scene because of concerns about another collapse.

A construction worker, Harold Simmons, said that several hundred workers were inside the entire building when the collapse happened."