The cost of a line connecting Moniaive to the G&SWR was estimated at £66,000, but local promoters only got commitment to £20,150 in subscriptions.
While also having significant gradients this route would be more moderate, and involved easier civil engineering, and had the advantage of reaching close to the County Burgh.
c. clxxii) of 6 August 1897 authorised the construction (along with several other G&SWR proposals): the line was named the Cairn Valley Railway, and its estimated cost was £165,840.
Inaction followed until the Board resolved to apply for a Light Railway Order (LRO) for the originally determined route, on 4 October 1898; the budget was reduced to £123,857.
The contractor successfully claimed compensation for unforeseen difficult ground conditions and was awarded £40,000 (over a contract price of £100,000) at arbitration.
[1][page needed][2][page needed] The Directors planned an official opening of the line for 31 December 1904, but this proved impossible as the Board of Trade Inspecting Officer was unable to schedule his visit to approve the opening; a celebratory dinner took place nonetheless.
The G&SWR decided to operate the Cairn Valley line with such a vehicle, and one was built at Kilmarnock Works for the purpose.
[2][page needed] The passenger carryings on the line did not live up to early expectation, and in fact declined from 4,800 journeys in 1906 to 3,600 in 1913, 2,500 in 1918 and dropping to 1,000 in 1923.
The other passing places were abolished, and the line from Dunscore to Moniaive was operated under the One Engine in Steam arrangement, with a train staff.
[2][page needed] The line was 17.5 miles (28.2 km) long and there were stations at Irongray, Newtonairds, Stepford, Dunscore, Crossford and Kirkland.
Irongray, Newtonairds, Dunscore and Moniaive were considered to be "stations" and had passing facilities (until 1936), while Crossford, Kirkland and Stepford were designated "stopping places", and had a simple wooden platform and small shelter for passengers.
The graceful brick built three-arch Dunscore Viaduct survives but is partly hidden by trees.