EDITORIAL : PAYING TWICE TAXPAYERS WON'T FAVOR CONVERTING PUBLIC HIGHWAYS TO RUSH-HOUR TOLLWAYS.

THE crowded freeways and roads of Southern California are familiar ground to the many motorists, car-poolers and mass-transit riders who travel on those routes each day.

As a result, many Los Angeles residents may be counted upon to support traffic planners who are searching for ways to make highways more efficient and less crowded.

As the Daily News reported Sunday, the traffic planners' work even includes conducting public-opinion surveys about various proposals to limit congestion on Southern California freeways.

But one of the more explosive ideas reportedly under consideration is ``congestion pricing,'' which means charging people a fee to drive on public freeways at peak-demand hours. That idea has the makings of a public-relations disaster.

Although we can't predict the exact outcome of the planners' opinion survey, it doesn't take a crystal ball to predict that people will rebel at the notion of paying to use public highways that they feel they already have paid for through gasoline taxes and state highway bonds.

Of course, it's true that a 1989 state law authorized toll roads on public land in California. The law allows private developers to build and manage toll roads, leasing the land for 35 years and then returning it to the state.

One such freeway opened in December consisting of toll lanes in the median of a 10-mile stretch of the Riverside (91) Freeway, which runs between Orange and Riverside counties. No state or federal money went into the $126 million project.

The privately financed and privately operated project provides four express lanes that allow travelers to avoid crowded conditions on the regular Riverside Freeway - but at a cost that varies according to demand.

The rate structure imposes different charges at different hours, from a high of $2.50 at peak periods when the road is very crowded to a low of 25 cents at night when the roads are nearly empty.

Given the state's tight fiscal condition and the need for highway improvements, such an approach makes practical sense. But for the most part, it makes sense only where new roads are built - not where older roads are converted or upgraded to tollways, and certainly not as a belated effort to reduce congestion through financial incentives or penalties.

Put in the simplest terms, the problem is that the public won't stand for the imposition of user fees on highways that once were free and were built using public funds in the first place.