The length of the railway between Risehill Tunnel and Garsdale Station includes the former water troughs. These were installed in 1907 at a cost of £4,396 and, when built, they were the highest water troughs in the world. The troughs ran from 255 miles 63 chains to 256 miles 8 chains (a distance of just over a quarter of a mile). It has been suggested that this location was chosen because there is plenty of water and because it is the only section of line between Settle and Carlisle that is straight enough and level enough. From one end of the troughs to the other, there are actually four gradient posts, indicating that the line is indeed relatively level for most of that length, although there is a slight gradient at either end (effectively making a shallow bowl shape).
Work on the dam for the reservoir lasted for nearly 12 months and it was carried out by between 50 and 60 men. Water flowed from the dam to a lineside tank house with a capacity of 43,000 gallons and this served the water troughs. Additional liquids were fed into the tank to keep the water clean and free-running, to soften the water and to prevent the interior of the boiler from rusting. In winter, the tank was kept heated by a boiler. Steam passed through copper pipes. A man on night-duty stoked up the fire using, for some of the time, coal that had been washed from the tenders of passing trains.
Each of the two 1,607 feet long troughs held between 5,000 and 6,000 gallons of water, a third of which would have been taken-up into the locomotive tender in a few dramatic moments. The troughs were designed to fill up, under normal circumstances, in about ten minutes. The scoop beneath the tender had to be wound down into the troughs at precisely the right time. An oil lamp mounted on top of a concrete post was located at the beginning of each trough. This was supposed to act as a marker after dark, but the light often went out. If the night was pitch-black, the crew would use their route knowledge and count the bridges so that they knew when to drop the scoop.
See also the accompanying article "The importance of water on steam-operated railways".
These notes are based on an article written by Keith Nunns for the November 2017 edition of the FoSCL Journal. They are used here with Keith's kind permission.