The railway line between Perth and Inverness should be dualled as a matter of priority, it has been claimed.
Scottish Green Party members want to see the Highland Mainline railway dualled in a bid to tackle pollution, reduce crashes on the adjacent A9 and prevent delays caused by breakdowns blocking the line.
The 118 miles of railway tracks between the Fair City and Inverness have not been electrified yet and most of the stretch is covered by a single set of tracks.
The main road which runs parallel to the tracks is undergoing a multi-billion pound upgrade which is scheduled to be completed in five years time.
The Scottish Greens say the move would drive freight trucks off the A9 and as well as lowering vehicle emissions, this would reduce the number of traffic accidents and damage done to road surfaces by heavy vehicles.
A party spokesperson said: “It isn’t right that in the 21st century, it’s often quicker to drive to the Highlands from the central belt, rather than get the train.
“This is because around two thirds of the 118-mile line to Inverness is still single track and not electrified. This limits capacity and makes journeys slower. One breakdown can, and regularly does, bring the whole network to a halt.
“The Highlands needs the economy and transport infrastructure of the 21st century, not be stuck in the past.”
The Scottish Government said it has already invested heavily in improving the rail service which connects the Highlands with the rest of Scotland.
National transport agency Transport Scotland said Holyrood will consider proposals for investment during an ongoing review of projects.
A spokesperson said: “The recent £57 million Highland Mainline investment has already delivered performance and resilience improvements.
“This sits alongside the £330 million Aberdeen to Inverness project which has delivered new stations at Forres and Kintore, improving overall connectivity in the North East and Highlands.
“Looking forward, the second Strategic Transport Projects Review (STPR2) currently underway will determine the Scottish Government’s future transport investment priorities and will include considering any rail infrastructure upgrades such as dualling the Highland Mainline.”