 By using an all glued laminated timber structure and woodworking joints to mate the giant timbers, with the joints being held together with wooden bolts and nuts, measurements from the EMP tests would not be skewed by large amounts of ferrous material in the structure.Some metal was used in the construction as critically loaded joints incorporated a circular steel sheer ring that surrounded the wooden bolt clamping the joint.Even the fire escape along one side of the trestle and the whole of the extensive fire suppression piping were constructed of fiberglass.