the history of Kelok 9 was built during the Dutch East Indies between 1908-1914. This road bends across the Barisan Hill which extends from north to south of Sumatra Island. If it is stretched straight, the length of the Nine Gorge is only 300 meters with a width of 5 meters and a height of about 80 meters.
Based on the Ministry of Public Works record, in one day this road passed more than 10 thousand units of vehicles and during holidays or big day celebration increased 2 to 3 times. However, since the construction of Kelok Sembilan barely experienced widening means due to constrained terrain. Along with the increased volume of vehicles that pass, the condition of a narrow and steep roads often lead to congestion. The width of the road is only 5 meters and the sharp curve often makes it difficult for large vehicles to pass because it is not strong uphill.
In 2000, vehicle traffic between West Sumatra and Riau was between 9,000 and 11,000 vehicles a day carrying about 15.8 million people and about 28.5 million tons of goods a year. Half of the goods transported are agricultural and livestock. Due to the narrowing of road in Kelok Sembilan, the journey from Bukittinggi to Pekanbaru that should be taken within 4 hours, can take 5 to 6 hours. Overcoming this problem, Head of West Sumatera Road Infrastructure Ir. Hediyanto W. Husaini proposed to the central government to build a flyover. Construction of Kelok 9 overpasses began in November 2003 after obtaining central government approval through the National Development Planning Agency in August 2003.
http://barukoe.blogspot.co.id/2014/07/payakumbuh-sejarah-berdirinya-kelok-9.html