It is the second northernmost railway in the United Kingdom with the first being the spur to Thurso on the Far North Line.
Pipeline segments are combined at a site on the inland end of the railway and then towed to the sea, using the vessels.
They are transported onto the railway by being taken to Georgemas Junction and then finish their journey to the Subsea 7 site by road.
Entire pipelines are transported along the rail, giving it the record for the longest thing ever to be transported by rail: a 7.7-kilometre (4.8 mi) long pipe, only 100 metres (330 ft) shorter than the main section of railway itself.
Four lines exist West of the bridge under the A99 road, however the main stem of the railway is just two tracks.