1) Main communication channel 2) Main railway route 3) Railroad artery 4) Switchboard connection 
The Trunk Line (Hovedbanen) is a railway line in Norway which runs between Oslo and Eidsvoll. The line is owned by the Norwegian National Rail Administration. ==History== Built by Robert Stephenson, the Trunk Line was opened on 1 September 1854 by the Norwegian Trunk Railway (Norsk Hoved-Jernbane), making it the oldest public railway line in Norwa...
[n] - line that is the main route on a railway 2. [n] - a telephone line connecting two exchanges directly
noun line that is the main route on a railway noun a telephone line connecting two exchanges directly