Barring a last-minute change of heart, the proposed North Shore casino appears to be headed for another court battle.

Unless it can get an 11th-hour agreement with developer Don Barden, the Carnegie Science Center plans to file an appeal with the state Supreme Court today challenging the city planning commission's approval of the casino master plan May 29.

At the same time, Mr. Barden is threatening his own litigation against the science center if it moves forward with an appeal. In that case, Mr. Barden and his company, PITG Gaming LLC, will "seek any remedies that might be available to us for appropriate relief under the law," spokesman Bob Oltmanns said yesterday.

"We continue to maintain the master site plan was approved fairly and properly according to the city planning code. Our proposal is in compliance with the ordinance and there is no reason why we shouldn't proceed," he said.

A court battle moved closer to reality after the science center rejected a proposal made Tuesday by Mr. Barden. It would have allowed the center to use the same access road for school buses it currently does.

Science center Director Joanna Haas said, however, the proposal might actually worsen the situation for school buses, particularly given the traffic the casino is likely to generate.

To force school buses to merge onto North Shore Drive from Reedsdale Street and to cut across four lanes of traffic to get into the center would make for "total chaos" and would be "completely unsafe," she said.

But Mr. Oltmanns said Mr. Barden plans to reconfigure the intersection and put a traffic signal there so vehicles can turn onto North Shore from Reedsdale unimpeded.

"We are making reasonable accommodations to make sure bus traffic can get to and from the science center easily. We offered a couple of different approaches to do that and they rejected them all," he said.

Despite the heated rhetoric, neither side slammed the door on talks heading into today's appeal deadline.

"Mr. Barden has directed the project team to make sure the door remains open," Mr. Oltmanns said.

The science center also plans to make a late run at an agreement, said Joel Aaronson, its attorney.

Allegheny County Chief Executive Dan Onorato also is working with the science center and Mr. Barden to try to reach a resolution and avoid a court battle, spokesman Kevin Evanto said.

Two other North Shore neighbors, the Steelers and the Pirates, also are considering appeals over traffic-related issues.

Even if there is an appeal of the master plan, Mr. Barden intends to move forward with project development plan approvals relating to the Majestic Star casino design, Mr. Oltmanns said.

Under the law he has a right to proceed while the appeal is pending.