The relocation of the railway was finally brought up again and in 1925 three alternative designs for a road-rail bridge were produced, with a street bridge passing alternatively to the east, to the west, or above the railway. While most agreed the southern part of the bridge should connect with Långholmsgatan on Södermalm passing over Långholmen, the connection to Kungsholmen gave several possibilities. Before finally settling the present location with the northern end of the bridge landing on Rålambshov, two other alternatives were considered; One further west, between Långholmen and Smedsudden, the shortest distance over Riddarfjärden, and one to the east, connecting the bridge directly to Sankt Eriksgatan much further north. 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. The final design was approved by the city in 1931. Västerbron was built simultaneously to the then modern traffic centre at Slussen and while the bridge was being built many people were wondering who was supposed to use it, believing its peripheral situation would prevent it from attracting any users. However, after only a year more than 12,000 cars used the bridge daily and before 1955 that number had increased fourfold, effectively using up all the capacity the bridge could offer. In 1955-56 the bridge was broadened 2 m, giving space to new bicycle lanes. The increasing traffic following WWII continued to strain the capacity of Västerbron. Much of the north-southern traffic flow through the old city centre remained confined to the bridge until the inauguration in 1966 of Essingeleden, the motorway running parallel to Västerbron about 1.5 km to the west. Today Västerbron is occasionally still acting as a reserve when Essingeleden is being closed off for repair and other reasons. From its opening Västerbron was an important passageway of Stockholm’s tram network until the last four lines of the network, one of them line 4 crossed over Västerbron, was closed in September 1967 simultaneously with the switch to right-hand side traffic.