The Basic Treaty of 1972 did not fundamentally alter transit routes to Berlin. The only changes that occurred were in the south. Two Autobahn checkpoints, Hirschberg and Rudolphstein (1972), were added after the Saal Bridge was rebuilt in the 1960s. In 1972, the Elbe-Seiten Canal (shown on this map) was still under construction; it was not completely open to river traffic until 1976. The opening of the canal created a direct waterway link to Hamburg. The Elbe-Seiten Canal also replaced a waterway on the Elbe (between Schnackenburg and Lauenburg) that had been the subject of border disputes and thus posed problems for captains. Above all, however, the 1972 treaty improved the practical use of access roads by means of well-ordered regulations, which were applicable to border controls, as well.