From 1924, car transport on trains through the railway tunnel began. The road between Göschenen and Airolo through the summit of the pass, comporting notably the Schöllenen ravine and the Tremola, had countless hairpin turns and serpentine curves, dropping in altitude. It posed a huge challenge for automobiles. From 1953 onwards, the pass road was sequentially improved and expanded at several sections along the Gotthard route, finally ending in 1977 with the opening of an expressway fully circumventing the Tremola. In winter, however, due to the snow, cars could only cross the Gotthard on the train.