London 2012 chairman Sebastian Coe added: "I am very grateful to Essex County Council and to the Salvation Army for their hard work in making this venue happen.
"The course is challenging with multiple climbs and descents for the riders to tackle and I believe that the mountain bike competition will be one of the most exciting events at the London 2012 Olympic Games."
Killeen was joined by GB team-mates David Fletcher, Kenta Gallagher and Lily Matthews for a test run of the course on Tuesday.
Mountain biking ticket prices range from £20 to £45, with concessions such as Pay Your Age also available.
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