CONGO BRIDGING THE PAST PRINCIPAL ARTERY OF COMMERCE IN THE CONGO WAS TRADITIONALLY THE CONGOLESE NATIONAL ROUTE, A 1,725-MILE RAIL-RIVERRAIL CONNECTION FROM ELISABETHVILLE IN KATANGA TO THE ATLANTIC GATEWAY AT MATADI . BUT THE ROUTE BECAME UNUSABLE WITH THE OUTBREAK OF CIVIL WAR . WHENEVER KATANGA'S SECESSIONIST MOISE TSHOMBE FELT EVENTS GOING AGAINST HIM, HE QUICKLY ORDERED ANOTHER RAILROAD BRIDGE BLOWN UP . THUS, SINCE 1960 MOST TRAFFIC HAS MOVED ON ALTERNATE RAIL LINES THROUGH PORTUGUESE ANGOLA AND MOZAMBIQUE . BUT THE ROUTES ACROSS FOREIGN TERRITORY SOAK UP REVENUE BADLY NEEDED WITHIN THE CONGO, AND LAST WEEK PREMIER CYRILLE ADOULA HOPEFULLY DEDICATED A NEW RAILROAD BRIDGE AT BUKAMA, THE FINAL REBUILT LINK IN THE KATANGA-MATADI RUN . " THIS IS NOT ONLY A BRIDGE OVER THE LUALABA RIVER, " SAID ADOULA . " IT IS A BRIDGE OVER THE UNHAPPY PAST . " THOUGH A MILESTONE OF SORTS, THE BUKAMA BRIDGE ALSO MARKS THE PETTY PACE OF CONGOLESE UNITY, FOR THE STEAMY 25-DAY TRIP BY BARGE AND BOXCAR REMAINS AN AWESOME OBSTACLE COURSE . SOME OF THE 23 CONGOLESE PROVINCES CREATED SINCE 1962 CLAIM AUTHORITY TO LEVY IMPORT-EXPORT DUTIES AS THE MOOD STRIKES THEM . ALSO, TRIBAL TENSIONS NECESSITATE FREQUENT CHANGES OF ENGINEERS AS TRAINS PASS FROM ONE REGION TO THE NEXT . IF THE LOCAL FOLK SPOT AN ENEMY AT THE CONTROLS, THEY MIGHT SWARM ABOARD AND KILL HIM ON THE SPOT .