Construction of the Cairngorm Mountain Railway started in 1999 and the railway opened on 24 December 2001. The construction was initiated because the chairlift was too sensitive to the strong winds in the area. The track is a broad gauge of. The maximum operating speed is during the ski season and the rest of the year. At these speeds, the trip takes about four minutes in winter and nine minutes during the summer. The single track line has a passing loop just above the middle station. During ascent, the maximum gradient is 23°. The railway starts at the Base Station in the Coire Cas area, where there is a restaurant, shop, ticket office, hire shop, rangers' office and Disability Sport UK office. The Scottish Ski Club has a building close to the middle station. At peak times there can be 150,000–160,000 non-winter sports visitors, combined with a further 50,000–120,000 annual sports visitors during the winter. CML can expect to cater to 1,000 visitors per day in the summer months. The railway is from Aviemore and can be reached travelling along the B970 and C38 roads to Glenmore. From Glenmore, a route is taken through the snow gates and via a one-way system past Coire na Ciste for approximately. The Base Station is at an altitude of approximately above sea level, the middle station is at approximately and the top Ptarmigan Station is at approximately. The total length of the funicular railway track is, during which the route rises by. Most of the route is single track, with a short passing loop near half way. Up to 120 standing passengers can be carried in each of the system's two carriages. The train is fully accessible for wheelchair users and both the Base Station and Ptarmigan Station have lift access to all levels. Depending on wind direction, wind speed trend and weather forecast, the trains can operate in winds of. As the train approaches the top station it enters a long cut-and-cover tunnel taking it up to the top platform hidden in the hillside. The funicular railway operates by 'hauling' up one carriage using electric motors to pull the haul rope as the other carriage descends at the same time. The system is powered by two stationary in series 500 kW electric motors, a gear box and a 'soft start-soft stop' control system which can increase the electrical frequency and vary the current and voltage to control the carriage speeds as they approach or leave a station. A hydraulically operated 'counter' rope is connected to both carriages to maintain haul rope tension. The two carriages are permanently connected by the haul rope and the counter rope and can never operate independently. The funicular railway system is normally operated from a manned control room within the Ptarmigan building, but can also be operated from the Base station control room or from each railway carriage. There are dedicated sophisticated computer control, instrumentation, communication and safety systems for the railway which have a range of back up systems and there are also standby generators and manual back up systems for moving the carriages. During the ski season, skiers are asked to stay within the designated ski area and climbers and hill walkers are not allowed to use the railway to travel uphill. The railway operators have agreed, in conjunction with Scottish Natural Heritage, to operate a formal visitor management plan to protect fragile areas of the mountain environment. This means that for conservation reasons, the public is not allowed to access the mountains during the summer season from Ptarmigan building. However, walkers who have climbed the hill themselves may purchase a downhill ticket at the Ptarmigan building for travelling back down to Base. There are no middle station stops or exits during the summer. On 29 November 2018, it was announced that the railway had been placed into administration. Blair Milne, one of the administrators, cited that the company had become "unsustainably loss-making" after an extended closure in October 2018. Natural Retreats, the previous owners since 2013, released a press statement saying the firm still had "potential". That hope did not come to fruition and the company owed £2m.
Closure
The closure of the Cairngorm Mountain Railway funicular was "due to health and safety concerns", or "structural problems" according to reports in summer 2019. At the time, an engineering investigation was still underway to determine whether modifications would be "achievable and affordable", according to its then-owner, the Scottish government's Highlands and Islands Enterprise which also owns Cairngorm Mountain ski centre. The final findings of the consultants, SE Group, were released in July 2019, but a decision on how to proceed had not yet been made at that time.
