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.