The biggest potential clash tonight might not be at Heinz Field but on the roads and ramps around it.

For the first time, visitors to the Rivers Casino, which opened Sunday on the North Shore near the stadium, will be mixing with the always-challenging Steelers traffic for the preseason game against Arizona.

"It's going to be a test for everybody, not only our business but their business because there is limited access and limited parking over here," said Jimmie Sacco, executive director of stadium management at Heinz Field.

The Rivers Casino will be the first in Pennsylvania to operate so close to a professional football stadium. As a result, casino officials aren't sure just what the impact will be, either on traffic or on play, although they are planning for big pre- and post-game crowds.

"We don't know what to expect. I think that's going to be the interesting part. We have enough staff on board to provide the level of service we want to provide," said George Matta, Rivers director of business development and community relations.

While the casino and the Steelers have been playing nice lately on traffic issues, the history between the two has been less than cordial.

The Steelers and the Pirates mounted a court battle two years ago over the city planning commission's approval of the casino's master plan.

At one point, the teams predicted the gambling complex would produce the equivalent of traffic armageddon for their fans, adding 90 minutes to 21/2 hours to their typical game-day commutes.

Then casino developer Don Barden criticized the projections. He claimed that, if anything, the Steelers traffic would keep slots players away in droves, cutting into his bottom line.

The dispute ended with a court-supervised settlement, the linchpin of which is a traffic management plan that will get its first test tonight.

As part of the plan, the casino will hire 10 city police officers to keep traffic flowing near its complex. That will be in addition to the police the city provides (12 before games and 24 after) and those that the Steelers chip in (18 before games and 26 to 30 after).

The casino also will be altering traffic patterns so that motorists leaving the property will be moved away from Heinz Field rather than into the teeth of the traffic.

Mark Hart, the Steelers' director of business, said one of the overall goals of the plan is to separate the casino traffic from the football traffic. If that can happen, "a lot of those worst-case scenarios" feared by the teams won't materialize, he said.

He advised fans who don't have reserved parking near Heinz Field to park Downtown or at Station Square. He also said they should give themselves plenty of time to get to tonight's 8 p.m. kickoff because of new traffic patterns and construction.

The Rivers will offer fans parking in its garage for $50 -- $20 to $25 above the going rates near Heinz Field. The fee is waived if at least $80 is bet at the casino.

Rivers and Steelers officials will meet after the first game to assess the success of the traffic plan and to determine what changes, if any, are needed.

Some don't anticipate much trouble tonight.

Merrill Stabile, president of Alco Parking Corp., which manages the lots near Heinz Field, thinks the casino impact will be minimal.

"I would characterize casino traffic as a slow trickle that occurs evenly over a 24-hour period," said Mr. Stabile. "I think there's going to be a natural tendency for people thinking about coming to the casino to adjust the time to before or after the game."

Just the same, the Steelers are keeping their fingers crossed. With rush hour, construction, the game, the casino and a Keith Urban concert at Mellon Arena, the potential for trouble lurks.They won't have to worry about Katie Bernarding of Baldwin Borough. She went to the Rivers on opening day to gamble. But she won't be at the slots venue during Steelers games.

"No way," she said. "I'm not dealing with that traffic."