The Pennsylvania Turnpike's chief executive, Joe Brimmeier, says he isn't worried about the impact on traffic volume stemming from a 25 percent toll increase scheduled to take effect Jan. 4 over nearly the entire 545-mile system. The only areas temporarily exempted from the increase are some newly opened sections in Western Pennsylvania.

"They'll (motorists) stay on our road because it's a good road, it's one of the safest interstates in the country and they can get from Point A to Point B much quicker," Brimmeier said.

The Turnpike chief pointed out that a 42.5 percent toll hike in 2004 did not reduce traffic and generated just 127 complaints to the Turnpike Commission.

A total of 190 million vehicles used the Turnpike last year.

Even if the upcoming toll hike doesn't negatively impact traffic volume, it's reasonable to ponder how long into the future that acceptance by motorists will continue — whether or not the toll road is leased eventually to a private operator.

The Jan. 4 increase will be just the sixth in 68 years, but the Turnpike intends to embark on a plan under which tolls will be increased by about 3 percent annually. No one can predict how long it will be before motorists finally say "Enough!" and opt for alternative routes, but that day seems destined to come eventually, if the increases persist.

For example, some motorists traveling to and from Washington, D.C., and points south could opt for Interstate 68 between Morgantown, W.Va., and Hancock, Md. As Turnpike tolls increase, that might be an increasingly tempting alternative to what fast is becoming the Keystone State's "Highway for the Well-To-Do."

All that said, it must be acknowledged that the Turnpike, despite having what is perceived to be a bloated staff as well as overly generous pay and benefits, is not solely to blame for the decision to raise tolls now and continue raising them in future years. If use of toll revenue were confined to the toll road itself, it would seem that the current tolls would be sufficient to pay the Turnpike's obligations and allow for Turnpike improvements.

However, in addition to helping to pay for the toll road's needs, Turnpike toll revenue helps subsidize 74 mass transit agencies and helps to repair other state roads and bridges.

To the mass transit agencies that can't exist just on passenger fares and the other government subsidies that they routinely receive, the Turnpike is a cash cow that allows those financially inefficient modes of moving people to keep their fares cheap and, in some instances, avoid difficult decisions that would make them more self-sustaining.

As in 2004, the upcoming increase probably won't cause a mass exodus of motorists, especially truckers. For the trucking companies, the toll increase can be built into the rates they charge for moving goods.

But the Turnpike also depends on a big volume of automobile traffic carrying people of all economic circumstances. Some of them with some time flexibility might choose to take a slower, alternative route rather than opt for expensive Turnpike expressway travel.

While it's unlikely that would paralyze the Turnpike from a financial standpoint, it would nonetheless negatively impact the toll road's finances — and the Turnpike needs all the money it can raise.

To keep Turnpike traffic volume healthy and hopefully avert the need for annual toll hikes without end, the Turnpike Commission must work to control costs — and the state government must keep its dependence on Turnpike revenue under control.

Neither should be regarded as impossible.

Meanwhile, Brimmeier should not be overconfident that a big toll increase won't cause a drop in Turnpike traffic volume, regardless of the 2004 experience.