The sign requirement was part of a number of bills that City Council passed after the June 2013 building collapse at 22d and Market Streets that killed six people and injured 14.
A contentious issue in the resulting investigations has been whether there was enough advance warning of demolition work that triggered the fatal collapse of a four-story brick wall onto the one-story Salvation Army thrift shop next door.
At sites of new construction, or demolition, of any building more than three stories high, owners or developers must put up a 3-by-5-foot sign - at their own expense - at least 24 hours before starting the work. The sign must include the address, owner, contractor, and work completion date, and has to list 311 and 911 as numbers to call to report dangerous conditions.
Projects of fewer than three stories have to post similar information on bright-yellow signs just larger than a legal-size letter and provided by L&I.
Sites caught without a sign may be fined $50 per day.
City Councilman Jim Kenney, who cosponsored the bills, said Thursday he was glad Nutter was implementing the legislation. But Kenney, who has hinted at a mayoral run next year, contended the administration is still not doing enough.
"I complain every day to L&I and [the Department of] Streets" about hazards, he said, mentioning places in Old City where sidewalks are blocked.
The newly required signs will make it easier for others to complain, too.