Pittsburgh City Council has tentatively approved a moratorium on new billboards, but Mayor Luke Ravenstahl's administration wants a private meeting to discuss the issue and is challenging the legality of an appeal on a proposed billboard at the new Grant Street Transportation Center.

In a meeting yesterday conducted in measured tones that contrasted with Tuesday's heated confrontations, council gave tentative approval to a resolution asking for a six-month moratorium on sign approvals. The vote was 3-0 with four abstentions and two members out of the room.

A final vote may come Tuesday, but first council plans to meet privately with Solicitor George Specter, at his request.

Mr. Specter was hesitant to provide a rationale for the planned closed-door session. Under state law, such "executive sessions" only can be held to discuss personnel matters, collective bargaining negotiations, the purchase or lease of property or "pending or threatened litigation." Mr. Specter said he would put it under the category of "threatened litigation," but would not say whether any entity has threatened to sue the city over billboard matters.

Separate legislation that would give council an up-or-down vote on all sign changes was referred to the city planning commission for review and a public hearing.

Action was postponed for four weeks on Councilman William Peduto's call for a formal investigation of a December decision by zoning administrator Susan Tymoczko to permit a 1,200-square-foot digital billboard on the Grant Street Transportation Center without any public hearings or votes.

That permit spawned council's billboard legislation, which in turn led to at least 65 new or modernized sign applications by Lamar Advertising, Liberty Pacific Media Inc. and U.S. Outdoor Advertising Inc. The companies filed immediately so their proposals would be in the pipeline before a moratorium could be enacted.

Councilman Patrick Dowd, acting as a private citizen, appealed the Grant Street Transportation Center billboard permit. On March 12, Mr. Peduto, council President Doug Shields, Councilmen Bruce Kraus and Ricky Burgess filed a very similar appeal in their official capacity.

City Chief of Staff Yarone Zober wrote to council yesterday saying that because the four members filed their March 12 appeal at around 4:15 p.m. -- 75 minutes after the zoning counter formally closes -- there needs to be an examination of "abuse of power and undue influence" by the council members.

"We need the Law Department to determine whether there has been any abuse of power here, any undue influence or anything irregular in filing documents with a city department later than the general public would be able to file the same documents," Mr. Zober said in an interview. He said there are no plans to refer the matter to the city's Office of Municipal Investigations or outside law enforcement.

Mr. Shields called Mr. Zober's communication "a very disingenuous attempt to disallow the representatives of the people access to their legal options." He said city Planning Director Noor Ismail allowed the 4:15 p.m. filing. "What are they afraid of?" he asked of the administration.

The Zoning Board of Adjustment has scheduled a hearing on the billboard appeal for April 10.