Highlands and Islands Labour MSP Rhoda Grant has expressed "extreme disappointment" that the Highland Main Line will see no double track improvements between Dalwhinnie and Newtonmore.
Transport Minister Humza Yousaf has said while Phase 2 of the Highland Main Line Enhancements Programme aims to deliver faster more frequent journeys by spring 2019 it will only see infrastructure improvements at key train passing points at Aviemore and Pitlochry.
"Currently there are no plans to double-track the Highland Main Line between Dalwhinnie and Newtonmore or other remaining sections of the line," he told Mrs Grant in reply to a Parliamentary Question.
Mrs Grant asked how many trains were cancelled or delayed following an incident last year when the northbound Caledonian Sleeper broke down on the single track north of Dalwhinnie.
Mr Yousaf admitted that, as a result of the sleeper locomotive breakdown, 10 ScotRail trains were cancelled in full and eight more in part: three trains which completed their journeys were delayed for more than five minutes and ScotRail services as a whole incurred 417 minutes of delay.
"This one incident on its own surely makes the case for investing in double track on the Highland Main Line," said Mrs Grant.
"Delays and cancellations only force passengers back onto the road. Any improvements in double track would also be good for rail freight transport.
"The state of our railway infrastructure is woeful in the Highlands. This week we hear about a landslip on the West Highland Line forcing closure for several days and then there’s the Far North Line and its need for the Lentran Loop, a dual stretch of track between Clachnaharry and Clunes which could remove congestion on the rail line and cut delays.
"Labour continues to call for public ownership of the railway to allow more investment in infrastructure. Passengers in this country already pay some of the highest fares in Western Europe for a service with too many delays, overcrowded trains and stops being skipped leaving people stranded."