Norra Länken ("The Northern Link") is an urban motorway in Stockholm. It forms the northern section of the orbital motorway around the Swedish capital ('Stockholms ringled') and is part of European route E4. For construction of tunnel NL51 on Norra Länken, Doka supplied a tunnel slab traveller assembled from SL-1 components, and a 'mounted-ahead' wall formwork consisting of Top50 elements.