West Germany's Kohl keeps lines of communication open to East

''Both sides want business as usual.''

This is how one Western European diplomat described relations between East Germany and the new West German government of Helmut Kohl.

Basically, though no German says so publicly, ''business as usual'' involves the buying of East-West German human contacts by the West German infusion of much-needed hard currency into the East German economy.

In particular, the next question to be resolved in relations - but only after the planned March 6 election here - will be the potential bartering down of East Germany's de facto visa fee for visitors in return for Western credits.

This will have to await evaluations of what is politically possible and desirable, after the election. The main reason for the East German raising of the fee two years ago seemed to be political - a wish to reduce the millions of West German visitors and their impact on East Germany at a time when the Solidarity trade union was transforming Polish society. The increased financial burden did cut the number of West German visitors to East Germany by more than 40 percent.

The issue of the visa fee - formally a compulsory, nonrefundable exchange of 25 West German marks ($10) per person per day at an artificial one-to-one rate - was discussed in at least two of three East-West German ministerial meetings this month.

The last of the ministerial get-togethers accompanied the opening of the new Berlin-Hamburg highway Nov. 20. West German Transportation Minister Werner Dollinger and his East German counterpart, Otto Arndt, joined in cutting the ribbon on the 1.2 billion mark ($500 million) road that will shave an hour off driving time between the West German port and (West) Berlin.

This highway - first planned back in the 1930s - took four years to build. It is by far the largest project to have been built in East Germany with West German money.

Preceding the traffic ministers' celebration by a few days was the meeting of West German Construction and City-Planning Minister Oskar Schneider and his East German counterpart, Wolfgang Junker. The occasion was the opening of an imaginative West German urban renewal exhibition in Magdeburg, East Germany.

Mr. Schneider, departing somewhat from his formal topic, took the opportunity to welcome East Germany's new interest in concluding East-West German cultural agreement. East Berlin broke off these negotiations in 1975, insisting that West Germany first give to it Prussian art treasures that before World War II were located in what is now East Berlin. In September East Germany suddenly said it was ready to negotiate agreement even without obtaining the Prussian works.

Even in the absence of a cultural treaty the East Germans have sent to West Germany a comprehensive exhibition of 19th-century Berlin artist and architect Karl Friedrich Schinkel. That exhibition just opened in Hamburg, also in the presence of high-level officials from both states.