sentences:  A sunken rock north of the navigable course in Riddarfjärden, appropriate for a bridge foundation, finally convinced the city council to commission the port authorities to launch an international competition for a bridge passing over the rock.The competition produced no less than 72 different designs, including arch bridges, girder bridges, and cable bridges.Winner of the competition in 1930 was the German team of the architects Otto Rudolf Salvisberg, Wilhelm Büning and Wilhelm Maelzer.