Campaigners are calling for a short rail loop to be built in the Far North Line (FNL) to prevent the serious service disruption caused by just one train being behind schedule.

There have been continuing fears over the future viability of the FNL, but the authorities insist they are investing in its future. It runs for 161 miles from Inverness to Wick, with a seven mile spur at the north end from Georgemas Junction to Thurso. The FNL is single track throughout, with passing loops. Of the 26 stations it calls at, only three are staffed and eight are request stops.

The section of through Easter Ross carries commuter trains to and from Inverness from the likes of Tain and Ardgay. Meanwhile the last stretch from Dingwall to the Highland capital is also used by the Kyle of Lochalsh service, popular with tourists. Muir of Ord is last place trains can pass, so it is in these final miles to Inverness that major problems can occur. Mike Lunan, convener of the Friends of the Far North Line campaign group, explained:

"At the moment if a train is coming from the north gets to Muir of Ord it should be 19 minutes from Inverness. But if it is 10 minutes late either the trains at Inverness have to wait throwing their schedule out for the day; or the train at Muir of Ord has to wait and will be almost an hour late . This again throws out the timetable out for the rest of the day because its carriages are needed on another services. Some can end up being cancelled altogether, often the Thurso connection."

The campaigners have just published a report by a rail consultant which recommends loop be built at Lentran, six miles from Inverness. Any trains from the north running a little late could wait there till those leaving Inverness, had passed.

Mr Lunan said it would only need to be 400 or 500 metres long and the estimated cost would be around £10m.

He said it would benefit tourists going to Kyle or Wick and Thurso, commuters to Inverness and occasional travellers.

"Trains that take commuters home can be either late, or even cancelled and that is just not on."

A Network Rail spokesman said the agency was committed to the line, however:

“We do not have plans to double-track sections of the line at this time. However, between 2014 and 2019, Network Rail is investing over £30million in the Far North line renewing track, raising line-speeds over level crossings, completing the upgrade of signalling equipment and improving earthworks and structures along the route.”