The wind tunnel tests also revealed that the actual accelerations in the top levels exceed the design accelerations. The solution to this problem was the design of a 730ton Tuned Mass Damper of a pendulum type (as described in page 41), which would counterbalance the swaying of the building and bring the accelerations to an acceptable level. This state-of-the-art system was engineered by Motioneering, a sister company of RWDI. It hangs from the 92-88 floor, with cable lengths of 11.5m (figure 49). The TMD uses the building motion to push and pull dashpots (giant shock absorbers), that convert the motion to heat by forcing fluid throughsmall internal openings.