is class B listed. Its nearby sister ‘Little Water of Fleet viaduct’ was demolished for a RAF exercise ordered by Winston Churchill in 1946. On the Stranraer to Portpatrick section, a three-span viaduct was necessary to cross the Piltanton Burn near Lochans; it had 36 ft 9in (11 m) spans with a height of 73 feet (22 m). The gradients on the Portpatrick Railway main line were severe: gently undulating from Castle Douglas to New Galloway, they then formed a stiff climb at 1 in 80 to Loch Skerrow, the alternately falling and rising at 1 in 76 to the summit at agethouse of Fleet. There was then an unbroken descent of 6½ miles (10½ km) at 1 in 80 to near Palnure. A less constant climb then led to a summit near the 40 milepost between Kirkcowan and Glenluce, then falling at a ruling gradient of 1 in 80 nearly to Challoch Junction. From Stranraer there was a stiff continuous climb at 1 in 72 to a summit at Colfin, at an elevation of 326 feet (99 m) above sea level, then a descent at 1 in 80 to Portpatrick. The line today Only the Stranraer Harbour to Challoch Junction section is open; and is now served by services on the Glasgow South Western Line. Connections to other lines At Castle Douglas to the Castle Douglas and Dumfries Railway At Castle Douglas to the Kirkcudbright Railway At Challoch Junction to the Girvan and Portpatrick Junction Railway See also List of closed railway stations in Britain Notes References Sources External links Railscot on Portpatrick Railway Railscot on Wigtownshire Railway Beeching closures in Scotland British joint railway companies Closed railway lines in Scotland Early Scottish railway companies Pre-grouping British railway companies Railway companies established in 1885 Railway companies disestablished in 1921 Railway lines closed in 1965 London, Midland and Scottish Railway constituents Transport in Dumfries and Galloway Borders of Scotland 1861 establishments in Scotland 1965 disestablishments in Scotland British companies established in 1885