In 1980, Republicans rebelled against the iniquity of the 55 mph national speed limit and denounced it in their platform. Democrats laughed. Republicans swept the West, where folks don't take kindly to the feds slowing down a fella's pickup.

But today there are stretches of the Interstate Highway System where traffic creeps at 30 mph because of potholes and crumbling pavement. What is the Republican administration going to do about these and similar problems?

If Drew Lewis, the secretary of transportation has his way, taxes will be raised. I mean, revenues will be enhanced. That is, costs will be recovered by, er, augmenting "user fees." Principally, Lewis wants a 4-cent increase in the federal tax on a gallon of gasoline.

Only the gallantry I learned at my father's knee keeps me from hooting when Republicans devise euphemisms to avoid saying "tax increases." But Lewis has a point about the gas tax being a user fee. He proposes raising $4 billion annually from the four-cent increase, and another $1 billion from other user fees, primarily on heavy trucks. About $1 billion would be dedicated to mass transit capital investments.

This last provision, although perhaps justifiable, muddies Lewis' argument. The lofty morality of user fees-- what makes them noble, whereas tax increases are yucky--is that users of a service should pay for it. But, if so, mass-transit users should pay for mass transit with their fares. Lewis is nothing if not nimble, and he argues that highway users should pay with "user fees" some of the costs of the mass transit they do not use, because highway users will benefit from more adequate highway capacity when more folks are using mass transit.

Oh, well. Lewis is not only secretary of sophistry, he is also secretary of transportation. And the transportation system has problems that are more serious than Lewis' casuistry about user fees.

>It has been well said that maintenance, as much as original construction, is a measure of a society's vitality. It also is a measure of maturity, of the willingness to make timely provision for the future. By this measure, America is increasingly deficient.

The Interstate Highway System is not yet completed, but 10 percent needs resurfacing immediately and almost half will need major repairs by 1995. Even a three-year deferral of repairs can triple the cost--not even counting inflation. In the next 15 years, 216,000 miles of other roads in rural areas will need at least resurfacing. (An Arizona county recently tore up 250 miles of paved roads and put down gravel because that was cheaper than repairing the potholes.)

The design life of a bridge is 50 years. Seventy-five percent of America's bridges are more than 45 years old. Forty percent are judged deficient. It would take $60 billion just to eliminate the backlog of needed bridge repairs.

It would take $6 billion just to replace transit buses that are more than 15 years old. New York City would need $110 billion over the next decade just to rehabilitate its transit system. It also must resurface much of its 6,000 miles of streets (and must repair most of its 2,400 miles of water system and 6,100 miles of sewer system).

Gasoline cost 31 cents a gallon in 1959, when the tax was last raised (to 4 cents). The price of gasoline has quadrupled, highway construction costs have risen 300 percent, and the four cents are worth less than one cent. A gas tax proportional to four cents on a 31-cent gallon would today be 16 cents on a $1.24 gallon, double what Lewis wants it to be.

Conservatives rightly describe indexing of tax brackets as a cure for "surreptitious, unlegislated" tax increases. They should, therefore, describe what has happened to the gasoline tax since 1959 as a "surreptitious, unlegislated" tax cut.

There are today many varieties of liberalism and conservatism, with interesting similarities and incongruities, rather like the Synoptic Gospels. Keeping track of them requires an intellectual micrometer. But unless I have missed something, there is not yet an ideological difference between conservatives and liberals regarding potholes. Whites and blacks, Jews and gentiles, WASPs and ethnics-- we are all against bridges falling down.

But many conservatives have not come to terms with this fact: private life --including private enterprise-- depends on a publicly provided physical infrastructure. It is not optional; neither is it inexpensive. It illustrates this fact: a substantial portion--perhaps 80 percent--of public spending is not really a subject of serious disagreement.